Imported Upstream version 1.14.0upstream/1.14.0

38 files changed, 3546 insertions, 3684 deletions

diff --git a/paramiko/__init__.py b/paramiko/__init__.py
index 648b595..4c62ad4 100644
--- a/paramiko/__init__.py
+++ b/paramiko/__init__.py
@@ -16,94 +16,53 @@
 # along with Paramiko; if not, write to the Free Software Foundation, Inc.,
 # 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA.
 
-"""
-I{Paramiko} (a combination of the esperanto words for "paranoid" and "friend")
-is a module for python 2.5 or greater that implements the SSH2 protocol for
-secure (encrypted and authenticated) connections to remote machines.  Unlike
-SSL (aka TLS), the SSH2 protocol does not require hierarchical certificates
-signed by a powerful central authority.  You may know SSH2 as the protocol that
-replaced C{telnet} and C{rsh} for secure access to remote shells, but the
-protocol also includes the ability to open arbitrary channels to remote
-services across an encrypted tunnel.  (This is how C{sftp} works, for example.)
-
-The high-level client API starts with creation of an L{SSHClient} object.
-For more direct control, pass a socket (or socket-like object) to a
-L{Transport}, and use L{start_server <Transport.start_server>} or
-L{start_client <Transport.start_client>} to negoatite
-with the remote host as either a server or client.  As a client, you are
-responsible for authenticating using a password or private key, and checking
-the server's host key.  I{(Key signature and verification is done by paramiko,
-but you will need to provide private keys and check that the content of a
-public key matches what you expected to see.)}  As a server, you are
-responsible for deciding which users, passwords, and keys to allow, and what
-kind of channels to allow.
-
-Once you have finished, either side may request flow-controlled L{Channel}s to
-the other side, which are python objects that act like sockets, but send and
-receive data over the encrypted session.
-
-Paramiko is written entirely in python (no C or platform-dependent code) and is
-released under the GNU Lesser General Public License (LGPL).
-
-Website: U{https://github.com/paramiko/paramiko/}
-
-Mailing list: U{paramiko@librelist.com<mailto:paramiko@librelist.com>}
-"""
-
 import sys
 
-if sys.version_info < (2, 5):
-    raise RuntimeError('You need python 2.5+ for this module.')
+if sys.version_info < (2, 6):
+    raise RuntimeError('You need Python 2.6+ for this module.')
 
 
 __author__ = "Jeff Forcier <jeff@bitprophet.org>"
-__version__ = "1.12.2"
+__version__ = "1.14.0"
 __version_info__ = tuple([ int(d) for d in __version__.split(".") ])
 __license__ = "GNU Lesser General Public License (LGPL)"
 
 
-from transport import SecurityOptions, Transport
-from client import SSHClient, MissingHostKeyPolicy, AutoAddPolicy, RejectPolicy, WarningPolicy
-from auth_handler import AuthHandler
-from channel import Channel, ChannelFile
-from ssh_exception import SSHException, PasswordRequiredException, \
+from paramiko.transport import SecurityOptions, Transport
+from paramiko.client import SSHClient, MissingHostKeyPolicy, AutoAddPolicy, RejectPolicy, WarningPolicy
+from paramiko.auth_handler import AuthHandler
+from paramiko.channel import Channel, ChannelFile
+from paramiko.ssh_exception import SSHException, PasswordRequiredException, \
     BadAuthenticationType, ChannelException, BadHostKeyException, \
     AuthenticationException, ProxyCommandFailure
-from server import ServerInterface, SubsystemHandler, InteractiveQuery
-from rsakey import RSAKey
-from dsskey import DSSKey
-from ecdsakey import ECDSAKey
-from sftp import SFTPError, BaseSFTP
-from sftp_client import SFTP, SFTPClient
-from sftp_server import SFTPServer
-from sftp_attr import SFTPAttributes
-from sftp_handle import SFTPHandle
-from sftp_si import SFTPServerInterface
-from sftp_file import SFTPFile
-from message import Message
-from packet import Packetizer
-from file import BufferedFile
-from agent import Agent, AgentKey
-from pkey import PKey
-from hostkeys import HostKeys
-from config import SSHConfig
-from proxy import ProxyCommand
-
-# fix module names for epydoc
-for c in locals().values():
-    if issubclass(type(c), type) or type(c).__name__ == 'classobj':
-        # classobj for exceptions :/
-        c.__module__ = __name__
-del c
-
-from common import AUTH_SUCCESSFUL, AUTH_PARTIALLY_SUCCESSFUL, AUTH_FAILED, \
-     OPEN_SUCCEEDED, OPEN_FAILED_ADMINISTRATIVELY_PROHIBITED,  OPEN_FAILED_CONNECT_FAILED, \
-     OPEN_FAILED_UNKNOWN_CHANNEL_TYPE, OPEN_FAILED_RESOURCE_SHORTAGE
-
-from sftp import SFTP_OK, SFTP_EOF, SFTP_NO_SUCH_FILE, SFTP_PERMISSION_DENIED, SFTP_FAILURE, \
-     SFTP_BAD_MESSAGE, SFTP_NO_CONNECTION, SFTP_CONNECTION_LOST, SFTP_OP_UNSUPPORTED
-
-from common import io_sleep
+from paramiko.server import ServerInterface, SubsystemHandler, InteractiveQuery
+from paramiko.rsakey import RSAKey
+from paramiko.dsskey import DSSKey
+from paramiko.ecdsakey import ECDSAKey
+from paramiko.sftp import SFTPError, BaseSFTP
+from paramiko.sftp_client import SFTP, SFTPClient
+from paramiko.sftp_server import SFTPServer
+from paramiko.sftp_attr import SFTPAttributes
+from paramiko.sftp_handle import SFTPHandle
+from paramiko.sftp_si import SFTPServerInterface
+from paramiko.sftp_file import SFTPFile
+from paramiko.message import Message
+from paramiko.packet import Packetizer
+from paramiko.file import BufferedFile
+from paramiko.agent import Agent, AgentKey
+from paramiko.pkey import PKey
+from paramiko.hostkeys import HostKeys
+from paramiko.config import SSHConfig
+from paramiko.proxy import ProxyCommand
+
+from paramiko.common import AUTH_SUCCESSFUL, AUTH_PARTIALLY_SUCCESSFUL, AUTH_FAILED, \
+    OPEN_SUCCEEDED, OPEN_FAILED_ADMINISTRATIVELY_PROHIBITED, OPEN_FAILED_CONNECT_FAILED, \
+    OPEN_FAILED_UNKNOWN_CHANNEL_TYPE, OPEN_FAILED_RESOURCE_SHORTAGE
+
+from paramiko.sftp import SFTP_OK, SFTP_EOF, SFTP_NO_SUCH_FILE, SFTP_PERMISSION_DENIED, SFTP_FAILURE, \
+    SFTP_BAD_MESSAGE, SFTP_NO_CONNECTION, SFTP_CONNECTION_LOST, SFTP_OP_UNSUPPORTED
+
+from paramiko.common import io_sleep
 
 __all__ = [ 'Transport',
             'SSHClient',
diff --git a/paramiko/_winapi.py b/paramiko/_winapi.py
index b875924..0d55d29 100644
--- a/paramiko/_winapi.py
+++ b/paramiko/_winapi.py
@@ -8,92 +8,96 @@ in jaraco.windows and asking the author to port the fixes back here.
 
 import ctypes
 import ctypes.wintypes
-import __builtin__
+from paramiko.py3compat import u
+try:
+    import builtins
+except ImportError:
+    import __builtin__ as builtins
 
 try:
-        USHORT = ctypes.wintypes.USHORT
+    USHORT = ctypes.wintypes.USHORT
 except AttributeError:
-        USHORT = ctypes.c_ushort
+    USHORT = ctypes.c_ushort
 
 ######################
 # jaraco.windows.error
 
 def format_system_message(errno):
-	"""
-	Call FormatMessage with a system error number to retrieve
-	the descriptive error message.
-	"""
-	# first some flags used by FormatMessageW
-	ALLOCATE_BUFFER = 0x100
-	ARGUMENT_ARRAY = 0x2000
-	FROM_HMODULE = 0x800
-	FROM_STRING = 0x400
-	FROM_SYSTEM = 0x1000
-	IGNORE_INSERTS = 0x200
-
-	# Let FormatMessageW allocate the buffer (we'll free it below)
-	# Also, let it know we want a system error message.
-	flags = ALLOCATE_BUFFER | FROM_SYSTEM
-	source = None
-	message_id = errno
-	language_id = 0
-	result_buffer = ctypes.wintypes.LPWSTR()
-	buffer_size = 0
-	arguments = None
-	bytes = ctypes.windll.kernel32.FormatMessageW(
-		flags,
-		source,
-		message_id,
-		language_id,
-		ctypes.byref(result_buffer),
-		buffer_size,
-		arguments,
-		)
-	# note the following will cause an infinite loop if GetLastError
-	#  repeatedly returns an error that cannot be formatted, although
-	#  this should not happen.
-	handle_nonzero_success(bytes)
-	message = result_buffer.value
-	ctypes.windll.kernel32.LocalFree(result_buffer)
-	return message
-
-
-class WindowsError(__builtin__.WindowsError):
-	"more info about errors at http://msdn.microsoft.com/en-us/library/ms681381(VS.85).aspx"
-
-	def __init__(self, value=None):
-		if value is None:
-			value = ctypes.windll.kernel32.GetLastError()
-		strerror = format_system_message(value)
-		super(WindowsError, self).__init__(value, strerror)
-
-	@property
-	def message(self):
-		return self.strerror
-
-	@property
-	def code(self):
-		return self.winerror
-
-	def __str__(self):
-		return self.message
-
-	def __repr__(self):
-		return '{self.__class__.__name__}({self.winerror})'.format(**vars())
+    """
+    Call FormatMessage with a system error number to retrieve
+    the descriptive error message.
+    """
+    # first some flags used by FormatMessageW
+    ALLOCATE_BUFFER = 0x100
+    ARGUMENT_ARRAY = 0x2000
+    FROM_HMODULE = 0x800
+    FROM_STRING = 0x400
+    FROM_SYSTEM = 0x1000
+    IGNORE_INSERTS = 0x200
+
+    # Let FormatMessageW allocate the buffer (we'll free it below)
+    # Also, let it know we want a system error message.
+    flags = ALLOCATE_BUFFER | FROM_SYSTEM
+    source = None
+    message_id = errno
+    language_id = 0
+    result_buffer = ctypes.wintypes.LPWSTR()
+    buffer_size = 0
+    arguments = None
+    format_bytes = ctypes.windll.kernel32.FormatMessageW(
+        flags,
+        source,
+        message_id,
+        language_id,
+        ctypes.byref(result_buffer),
+        buffer_size,
+        arguments,
+    )
+    # note the following will cause an infinite loop if GetLastError
+    #  repeatedly returns an error that cannot be formatted, although
+    #  this should not happen.
+    handle_nonzero_success(format_bytes)
+    message = result_buffer.value
+    ctypes.windll.kernel32.LocalFree(result_buffer)
+    return message
+
+
+class WindowsError(builtins.WindowsError):
+    "more info about errors at http://msdn.microsoft.com/en-us/library/ms681381(VS.85).aspx"
+
+    def __init__(self, value=None):
+        if value is None:
+            value = ctypes.windll.kernel32.GetLastError()
+        strerror = format_system_message(value)
+        super(WindowsError, self).__init__(value, strerror)
+
+    @property
+    def message(self):
+        return self.strerror
+
+    @property
+    def code(self):
+        return self.winerror
+
+    def __str__(self):
+        return self.message
+
+    def __repr__(self):
+        return '{self.__class__.__name__}({self.winerror})'.format(**vars())
 
 def handle_nonzero_success(result):
-	if result == 0:
-		raise WindowsError()
+    if result == 0:
+        raise WindowsError()
 
 
 CreateFileMapping = ctypes.windll.kernel32.CreateFileMappingW
 CreateFileMapping.argtypes = [
-	ctypes.wintypes.HANDLE,
-	ctypes.c_void_p,
-	ctypes.wintypes.DWORD,
-	ctypes.wintypes.DWORD,
-	ctypes.wintypes.DWORD,
-	ctypes.wintypes.LPWSTR,
+    ctypes.wintypes.HANDLE,
+    ctypes.c_void_p,
+    ctypes.wintypes.DWORD,
+    ctypes.wintypes.DWORD,
+    ctypes.wintypes.DWORD,
+    ctypes.wintypes.LPWSTR,
 ]
 CreateFileMapping.restype = ctypes.wintypes.HANDLE
 
@@ -101,174 +105,174 @@ MapViewOfFile = ctypes.windll.kernel32.MapViewOfFile
 MapViewOfFile.restype = ctypes.wintypes.HANDLE
 
 class MemoryMap(object):
-	"""
-	A memory map object which can have security attributes overrideden.
-	"""
-	def __init__(self, name, length, security_attributes=None):
-		self.name = name
-		self.length = length
-		self.security_attributes = security_attributes
-		self.pos = 0
-
-	def __enter__(self):
-		p_SA = (
-			ctypes.byref(self.security_attributes)
-			if self.security_attributes else None
-		)
-		INVALID_HANDLE_VALUE = -1
-		PAGE_READWRITE = 0x4
-		FILE_MAP_WRITE = 0x2
-		filemap = ctypes.windll.kernel32.CreateFileMappingW(
-			INVALID_HANDLE_VALUE, p_SA, PAGE_READWRITE, 0, self.length,
-			unicode(self.name))
-		handle_nonzero_success(filemap)
-		if filemap == INVALID_HANDLE_VALUE:
-			raise Exception("Failed to create file mapping")
-		self.filemap = filemap
-		self.view = MapViewOfFile(filemap, FILE_MAP_WRITE, 0, 0, 0)
-		return self
-
-	def seek(self, pos):
-		self.pos = pos
-
-	def write(self, msg):
-		n = len(msg)
-		if self.pos + n >= self.length:  # A little safety.
-			raise ValueError("Refusing to write %d bytes" % n)
-		ctypes.windll.kernel32.RtlMoveMemory(self.view + self.pos, msg, n)
-		self.pos += n
-
-	def read(self, n):
-		"""
-		Read n bytes from mapped view.
-		"""
-		out = ctypes.create_string_buffer(n)
-		ctypes.windll.kernel32.RtlMoveMemory(out, self.view + self.pos, n)
-		self.pos += n
-		return out.raw
-
-	def __exit__(self, exc_type, exc_val, tb):
-		ctypes.windll.kernel32.UnmapViewOfFile(self.view)
-		ctypes.windll.kernel32.CloseHandle(self.filemap)
+    """
+    A memory map object which can have security attributes overrideden.
+    """
+    def __init__(self, name, length, security_attributes=None):
+        self.name = name
+        self.length = length
+        self.security_attributes = security_attributes
+        self.pos = 0
+
+    def __enter__(self):
+        p_SA = (
+            ctypes.byref(self.security_attributes)
+            if self.security_attributes else None
+        )
+        INVALID_HANDLE_VALUE = -1
+        PAGE_READWRITE = 0x4
+        FILE_MAP_WRITE = 0x2
+        filemap = ctypes.windll.kernel32.CreateFileMappingW(
+            INVALID_HANDLE_VALUE, p_SA, PAGE_READWRITE, 0, self.length,
+            u(self.name))
+        handle_nonzero_success(filemap)
+        if filemap == INVALID_HANDLE_VALUE:
+            raise Exception("Failed to create file mapping")
+        self.filemap = filemap
+        self.view = MapViewOfFile(filemap, FILE_MAP_WRITE, 0, 0, 0)
+        return self
+
+    def seek(self, pos):
+        self.pos = pos
+
+    def write(self, msg):
+        n = len(msg)
+        if self.pos + n >= self.length:  # A little safety.
+            raise ValueError("Refusing to write %d bytes" % n)
+        ctypes.windll.kernel32.RtlMoveMemory(self.view + self.pos, msg, n)
+        self.pos += n
+
+    def read(self, n):
+        """
+        Read n bytes from mapped view.
+        """
+        out = ctypes.create_string_buffer(n)
+        ctypes.windll.kernel32.RtlMoveMemory(out, self.view + self.pos, n)
+        self.pos += n
+        return out.raw
+
+    def __exit__(self, exc_type, exc_val, tb):
+        ctypes.windll.kernel32.UnmapViewOfFile(self.view)
+        ctypes.windll.kernel32.CloseHandle(self.filemap)
 
 #########################
 # jaraco.windows.security
 
 class TokenInformationClass:
-	TokenUser = 1
+    TokenUser = 1
 
 class TOKEN_USER(ctypes.Structure):
-	num = 1
-	_fields_ = [
-		('SID', ctypes.c_void_p),
-		('ATTRIBUTES', ctypes.wintypes.DWORD),
-	]
+    num = 1
+    _fields_ = [
+        ('SID', ctypes.c_void_p),
+        ('ATTRIBUTES', ctypes.wintypes.DWORD),
+    ]
 
 
 class SECURITY_DESCRIPTOR(ctypes.Structure):
-	"""
-	typedef struct _SECURITY_DESCRIPTOR
-		{
-		UCHAR Revision;
-		UCHAR Sbz1;
-		SECURITY_DESCRIPTOR_CONTROL Control;
-		PSID Owner;
-		PSID Group;
-		PACL Sacl;
-		PACL Dacl;
-		}   SECURITY_DESCRIPTOR;
-	"""
-	SECURITY_DESCRIPTOR_CONTROL = USHORT
-	REVISION = 1
-
-	_fields_ = [
-		('Revision', ctypes.c_ubyte),
-		('Sbz1', ctypes.c_ubyte),
-		('Control', SECURITY_DESCRIPTOR_CONTROL),
-		('Owner', ctypes.c_void_p),
-		('Group', ctypes.c_void_p),
-		('Sacl', ctypes.c_void_p),
-		('Dacl', ctypes.c_void_p),
-	]
+    """
+    typedef struct _SECURITY_DESCRIPTOR
+        {
+        UCHAR Revision;
+        UCHAR Sbz1;
+        SECURITY_DESCRIPTOR_CONTROL Control;
+        PSID Owner;
+        PSID Group;
+        PACL Sacl;
+        PACL Dacl;
+        }   SECURITY_DESCRIPTOR;
+    """
+    SECURITY_DESCRIPTOR_CONTROL = USHORT
+    REVISION = 1
+
+    _fields_ = [
+        ('Revision', ctypes.c_ubyte),
+        ('Sbz1', ctypes.c_ubyte),
+        ('Control', SECURITY_DESCRIPTOR_CONTROL),
+        ('Owner', ctypes.c_void_p),
+        ('Group', ctypes.c_void_p),
+        ('Sacl', ctypes.c_void_p),
+        ('Dacl', ctypes.c_void_p),
+    ]
 
 class SECURITY_ATTRIBUTES(ctypes.Structure):
-	"""
-	typedef struct _SECURITY_ATTRIBUTES {
-		DWORD  nLength;
-		LPVOID lpSecurityDescriptor;
-		BOOL   bInheritHandle;
-	} SECURITY_ATTRIBUTES;
-	"""
-	_fields_ = [
-		('nLength', ctypes.wintypes.DWORD),
-		('lpSecurityDescriptor', ctypes.c_void_p),
-		('bInheritHandle', ctypes.wintypes.BOOL),
-	]
-
-	def __init__(self, *args, **kwargs):
-		super(SECURITY_ATTRIBUTES, self).__init__(*args, **kwargs)
-		self.nLength = ctypes.sizeof(SECURITY_ATTRIBUTES)
-
-	def _get_descriptor(self):
-		return self._descriptor
-	def _set_descriptor(self, descriptor):
-		self._descriptor = descriptor
-		self.lpSecurityDescriptor = ctypes.addressof(descriptor)
-	descriptor = property(_get_descriptor, _set_descriptor)
+    """
+    typedef struct _SECURITY_ATTRIBUTES {
+        DWORD  nLength;
+        LPVOID lpSecurityDescriptor;
+        BOOL   bInheritHandle;
+    } SECURITY_ATTRIBUTES;
+    """
+    _fields_ = [
+        ('nLength', ctypes.wintypes.DWORD),
+        ('lpSecurityDescriptor', ctypes.c_void_p),
+        ('bInheritHandle', ctypes.wintypes.BOOL),
+    ]
+
+    def __init__(self, *args, **kwargs):
+        super(SECURITY_ATTRIBUTES, self).__init__(*args, **kwargs)
+        self.nLength = ctypes.sizeof(SECURITY_ATTRIBUTES)
+
+    def _get_descriptor(self):
+        return self._descriptor
+    def _set_descriptor(self, descriptor):
+        self._descriptor = descriptor
+        self.lpSecurityDescriptor = ctypes.addressof(descriptor)
+    descriptor = property(_get_descriptor, _set_descriptor)
 
 def GetTokenInformation(token, information_class):
-	"""
-	Given a token, get the token information for it.
-	"""
-	data_size = ctypes.wintypes.DWORD()
-	ctypes.windll.advapi32.GetTokenInformation(token, information_class.num,
-		0, 0, ctypes.byref(data_size))
-	data = ctypes.create_string_buffer(data_size.value)
-	handle_nonzero_success(ctypes.windll.advapi32.GetTokenInformation(token,
-		information_class.num,
-		ctypes.byref(data), ctypes.sizeof(data),
-		ctypes.byref(data_size)))
-	return ctypes.cast(data, ctypes.POINTER(TOKEN_USER)).contents
+    """
+    Given a token, get the token information for it.
+    """
+    data_size = ctypes.wintypes.DWORD()
+    ctypes.windll.advapi32.GetTokenInformation(token, information_class.num,
+        0, 0, ctypes.byref(data_size))
+    data = ctypes.create_string_buffer(data_size.value)
+    handle_nonzero_success(ctypes.windll.advapi32.GetTokenInformation(token,
+        information_class.num,
+        ctypes.byref(data), ctypes.sizeof(data),
+        ctypes.byref(data_size)))
+    return ctypes.cast(data, ctypes.POINTER(TOKEN_USER)).contents
 
 class TokenAccess:
-	TOKEN_QUERY = 0x8
+    TOKEN_QUERY = 0x8
 
 def OpenProcessToken(proc_handle, access):
-	result = ctypes.wintypes.HANDLE()
-	proc_handle = ctypes.wintypes.HANDLE(proc_handle)
-	handle_nonzero_success(ctypes.windll.advapi32.OpenProcessToken(
-		proc_handle, access, ctypes.byref(result)))
-	return result
+    result = ctypes.wintypes.HANDLE()
+    proc_handle = ctypes.wintypes.HANDLE(proc_handle)
+    handle_nonzero_success(ctypes.windll.advapi32.OpenProcessToken(
+        proc_handle, access, ctypes.byref(result)))
+    return result
 
 def get_current_user():
-	"""
-	Return a TOKEN_USER for the owner of this process.
-	"""
-	process = OpenProcessToken(
-		ctypes.windll.kernel32.GetCurrentProcess(),
-		TokenAccess.TOKEN_QUERY,
-	)
-	return GetTokenInformation(process, TOKEN_USER)
+    """
+    Return a TOKEN_USER for the owner of this process.
+    """
+    process = OpenProcessToken(
+        ctypes.windll.kernel32.GetCurrentProcess(),
+        TokenAccess.TOKEN_QUERY,
+    )
+    return GetTokenInformation(process, TOKEN_USER)
 
 def get_security_attributes_for_user(user=None):
-	"""
-	Return a SECURITY_ATTRIBUTES structure with the SID set to the
-	specified user (uses current user if none is specified).
-	"""
-	if user is None:
-		user = get_current_user()
-
-	assert isinstance(user, TOKEN_USER), "user must be TOKEN_USER instance"
-
-	SD = SECURITY_DESCRIPTOR()
-	SA = SECURITY_ATTRIBUTES()
-	# by attaching the actual security descriptor, it will be garbage-
-	# collected with the security attributes
-	SA.descriptor = SD
-	SA.bInheritHandle = 1
-
-	ctypes.windll.advapi32.InitializeSecurityDescriptor(ctypes.byref(SD),
-		SECURITY_DESCRIPTOR.REVISION)
-	ctypes.windll.advapi32.SetSecurityDescriptorOwner(ctypes.byref(SD),
-		user.SID, 0)
-	return SA
+    """
+    Return a SECURITY_ATTRIBUTES structure with the SID set to the
+    specified user (uses current user if none is specified).
+    """
+    if user is None:
+        user = get_current_user()
+
+    assert isinstance(user, TOKEN_USER), "user must be TOKEN_USER instance"
+
+    SD = SECURITY_DESCRIPTOR()
+    SA = SECURITY_ATTRIBUTES()
+    # by attaching the actual security descriptor, it will be garbage-
+    # collected with the security attributes
+    SA.descriptor = SD
+    SA.bInheritHandle = 1
+
+    ctypes.windll.advapi32.InitializeSecurityDescriptor(ctypes.byref(SD),
+        SECURITY_DESCRIPTOR.REVISION)
+    ctypes.windll.advapi32.SetSecurityDescriptorOwner(ctypes.byref(SD),
+        user.SID, 0)
+    return SA
diff --git a/paramiko/agent.py b/paramiko/agent.py
index 23a5a2e..5a08d45 100644
--- a/paramiko/agent.py
+++ b/paramiko/agent.py
@@ -17,7 +17,7 @@
 # 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA.
 
 """
-SSH Agent interface for Unix clients.
+SSH Agent interface
 """
 
 import os
@@ -29,28 +29,21 @@ import time
 import tempfile
 import stat
 from select import select
+from paramiko.common import asbytes, io_sleep
+from paramiko.py3compat import byte_chr
 
 from paramiko.ssh_exception import SSHException
 from paramiko.message import Message
 from paramiko.pkey import PKey
-from paramiko.channel import Channel
-from paramiko.common import io_sleep
 from paramiko.util import retry_on_signal
 
-SSH2_AGENTC_REQUEST_IDENTITIES, SSH2_AGENT_IDENTITIES_ANSWER, \
-    SSH2_AGENTC_SIGN_REQUEST, SSH2_AGENT_SIGN_RESPONSE = range(11, 15)
+cSSH2_AGENTC_REQUEST_IDENTITIES = byte_chr(11)
+SSH2_AGENT_IDENTITIES_ANSWER = 12
+cSSH2_AGENTC_SIGN_REQUEST = byte_chr(13)
+SSH2_AGENT_SIGN_RESPONSE = 14
 
-class AgentSSH(object):
-    """
-    Client interface for using private keys from an SSH agent running on the
-    local machine.  If an SSH agent is running, this class can be used to
-    connect to it and retreive L{PKey} objects which can be used when
-    attempting to authenticate to remote SSH servers.
 
-    Because the SSH agent protocol uses environment variables and unix-domain
-    sockets, this probably doesn't work on Windows.  It does work on most
-    posix platforms though (Linux and MacOS X, for example).
-    """
+class AgentSSH(object):
     def __init__(self):
         self._conn = None
         self._keys = ()
@@ -61,19 +54,20 @@ class AgentSSH(object):
         no SSH agent was running (or it couldn't be contacted), an empty list
         will be returned.
 
-        @return: a list of keys available on the SSH agent
-        @rtype: tuple of L{AgentKey}
+        :return:
+            a tuple of `.AgentKey` objects representing keys available on the
+            SSH agent
         """
         return self._keys
 
     def _connect(self, conn):
         self._conn = conn
-        ptype, result = self._send_message(chr(SSH2_AGENTC_REQUEST_IDENTITIES))
+        ptype, result = self._send_message(cSSH2_AGENTC_REQUEST_IDENTITIES)
         if ptype != SSH2_AGENT_IDENTITIES_ANSWER:
             raise SSHException('could not get keys from ssh-agent')
         keys = []
         for i in range(result.get_int()):
-            keys.append(AgentKey(self, result.get_string()))
+            keys.append(AgentKey(self, result.get_binary()))
             result.get_string()
         self._keys = tuple(keys)
 
@@ -83,7 +77,7 @@ class AgentSSH(object):
         self._keys = ()
 
     def _send_message(self, msg):
-        msg = str(msg)
+        msg = asbytes(msg)
         self._conn.send(struct.pack('>I', len(msg)) + msg)
         l = self._read_all(4)
         msg = Message(self._read_all(struct.unpack('>I', l)[0]))
@@ -100,8 +94,11 @@ class AgentSSH(object):
             result += extra
         return result
 
+
 class AgentProxyThread(threading.Thread):
-    """ Class in charge of communication between two chan """
+    """
+    Class in charge of communication between two channels.
+    """
     def __init__(self, agent):
         threading.Thread.__init__(self, target=self.run)
         self._agent = agent
@@ -109,7 +106,7 @@ class AgentProxyThread(threading.Thread):
 
     def run(self):
         try:
-            (r,addr) = self.get_connection()
+            (r, addr) = self.get_connection()
             self.__inr = r
             self.__addr = addr
             self._agent.connect()
@@ -146,6 +143,7 @@ class AgentProxyThread(threading.Thread):
         self.__inr.close()
         self._agent._conn.close()
 
+
 class AgentLocalProxy(AgentProxyThread):
     """
     Class to be used when wanting to ask a local SSH Agent being
@@ -155,18 +153,20 @@ class AgentLocalProxy(AgentProxyThread):
         AgentProxyThread.__init__(self, agent)
 
     def get_connection(self):
-        """ Return a pair of socket object and string address
-        May Block !
+        """
+        Return a pair of socket object and string address.
+
+        May block!
         """
         conn = socket.socket(socket.AF_UNIX, socket.SOCK_STREAM)
         try:
             conn.bind(self._agent._get_filename())
             conn.listen(1)
-            (r,addr) = conn.accept()
-            return (r, addr)
+            (r, addr) = conn.accept()
+            return r, addr
         except:
             raise
-        return None
+
 
 class AgentRemoteProxy(AgentProxyThread):
     """
@@ -177,22 +177,20 @@ class AgentRemoteProxy(AgentProxyThread):
         self.__chan = chan
 
     def get_connection(self):
-        """
-        Class to be used when wanting to ask a local SSH Agent being
-        asked from a remote fake agent (so use a unix socket for ex.)
-        """
-        return (self.__chan, None)
+        return self.__chan, None
+
 
 class AgentClientProxy(object):
     """
     Class proxying request as a client:
-       -> client ask for a request_forward_agent()
-       -> server creates a proxy and a fake SSH Agent
-       -> server ask for establishing a connection when needed,
+
+    #. client ask for a request_forward_agent()
+    #. server creates a proxy and a fake SSH Agent
+    #. server ask for establishing a connection when needed,
        calling the forward_agent_handler at client side.
-       -> the forward_agent_handler launch a thread for connecting
+    #. the forward_agent_handler launch a thread for connecting
        the remote fake agent and the local agent
-       -> Communication occurs ...
+    #. Communication occurs ...
     """
     def __init__(self, chanRemote):
         self._conn = None
@@ -205,7 +203,7 @@ class AgentClientProxy(object):
 
     def connect(self):
         """
-        Method automatically called by the run() method of the AgentProxyThread
+        Method automatically called by ``AgentProxyThread.run``.
         """
         if ('SSH_AUTH_SOCK' in os.environ) and (sys.platform != 'win32'):
             conn = socket.socket(socket.AF_UNIX, socket.SOCK_STREAM)
@@ -215,7 +213,7 @@ class AgentClientProxy(object):
                 # probably a dangling env var: the ssh agent is gone
                 return
         elif sys.platform == 'win32':
-            import win_pageant
+            import paramiko.win_pageant as win_pageant
             if win_pageant.can_talk_to_agent():
                 conn = win_pageant.PageantConnection()
             else:
@@ -236,11 +234,12 @@ class AgentClientProxy(object):
         if self._conn is not None:
             self._conn.close()
 
+
 class AgentServerProxy(AgentSSH):
     """
-    @param t : transport used for the Forward for SSH Agent communication
+    :param .Transport t: Transport used for SSH Agent communication forwarding
 
-    @raise SSHException: mostly if we lost the agent
+    :raises SSHException: mostly if we lost the agent
     """
     def __init__(self, t):
         AgentSSH.__init__(self)
@@ -276,16 +275,15 @@ class AgentServerProxy(AgentSSH):
         """
         Helper for the environnement under unix
 
-        @return: the SSH_AUTH_SOCK Environnement variables
-        @rtype: dict
+        :return:
+            a dict containing the ``SSH_AUTH_SOCK`` environnement variables
         """
-        env = {}
-        env['SSH_AUTH_SOCK'] = self._get_filename()
-        return env
+        return {'SSH_AUTH_SOCK': self._get_filename()}
 
     def _get_filename(self):
         return self._file
 
+
 class AgentRequestHandler(object):
     def __init__(self, chanClient):
         self._conn = None
@@ -303,27 +301,22 @@ class AgentRequestHandler(object):
         for p in self.__clientProxys:
             p.close()
 
+
 class Agent(AgentSSH):
     """
     Client interface for using private keys from an SSH agent running on the
     local machine.  If an SSH agent is running, this class can be used to
-    connect to it and retreive L{PKey} objects which can be used when
+    connect to it and retreive `.PKey` objects which can be used when
     attempting to authenticate to remote SSH servers.
 
-    Because the SSH agent protocol uses environment variables and unix-domain
-    sockets, this probably doesn't work on Windows.  It does work on most
-    posix platforms though (Linux and MacOS X, for example).
-    """
+    Upon initialization, a session with the local machine's SSH agent is
+    opened, if one is running. If no agent is running, initialization will
+    succeed, but `get_keys` will return an empty tuple.
 
+    :raises SSHException:
+        if an SSH agent is found, but speaks an incompatible protocol
+    """
     def __init__(self):
-        """
-        Open a session with the local machine's SSH agent, if one is running.
-        If no agent is running, initialization will succeed, but L{get_keys}
-        will return an empty tuple.
-
-        @raise SSHException: if an SSH agent is found, but speaks an
-            incompatible protocol
-        """
         AgentSSH.__init__(self)
 
         if ('SSH_AUTH_SOCK' in os.environ) and (sys.platform != 'win32'):
@@ -334,7 +327,7 @@ class Agent(AgentSSH):
                 # probably a dangling env var: the ssh agent is gone
                 return
         elif sys.platform == 'win32':
-            import win_pageant
+            from . import win_pageant
             if win_pageant.can_talk_to_agent():
                 conn = win_pageant.PageantConnection()
             else:
@@ -350,31 +343,34 @@ class Agent(AgentSSH):
         """
         self._close()
 
+
 class AgentKey(PKey):
     """
     Private key held in a local SSH agent.  This type of key can be used for
     authenticating to a remote server (signing).  Most other key operations
     work as expected.
     """
-
     def __init__(self, agent, blob):
         self.agent = agent
         self.blob = blob
-        self.name = Message(blob).get_string()
+        self.name = Message(blob).get_text()
 
-    def __str__(self):
+    def asbytes(self):
         return self.blob
 
+    def __str__(self):
+        return self.asbytes()
+
     def get_name(self):
         return self.name
 
-    def sign_ssh_data(self, rng, data):
+    def sign_ssh_data(self, data):
         msg = Message()
-        msg.add_byte(chr(SSH2_AGENTC_SIGN_REQUEST))
+        msg.add_byte(cSSH2_AGENTC_SIGN_REQUEST)
         msg.add_string(self.blob)
         msg.add_string(data)
         msg.add_int(0)
         ptype, result = self.agent._send_message(msg)
         if ptype != SSH2_AGENT_SIGN_RESPONSE:
             raise SSHException('key cannot be used for signing')
-        return result.get_string()
+        return result.get_binary()
diff --git a/paramiko/auth_handler.py b/paramiko/auth_handler.py
index acb7c8b..57babef 100644
--- a/paramiko/auth_handler.py
+++ b/paramiko/auth_handler.py
@@ -17,18 +17,21 @@
 # 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA.
 
 """
-L{AuthHandler}
+`.AuthHandler`
 """
 
-import threading
 import weakref
+from paramiko.common import cMSG_SERVICE_REQUEST, cMSG_DISCONNECT, \
+    DISCONNECT_SERVICE_NOT_AVAILABLE, DISCONNECT_NO_MORE_AUTH_METHODS_AVAILABLE, \
+    cMSG_USERAUTH_REQUEST, cMSG_SERVICE_ACCEPT, DEBUG, AUTH_SUCCESSFUL, INFO, \
+    cMSG_USERAUTH_SUCCESS, cMSG_USERAUTH_FAILURE, AUTH_PARTIALLY_SUCCESSFUL, \
+    cMSG_USERAUTH_INFO_REQUEST, WARNING, AUTH_FAILED, cMSG_USERAUTH_PK_OK, \
+    cMSG_USERAUTH_INFO_RESPONSE, MSG_SERVICE_REQUEST, MSG_SERVICE_ACCEPT, \
+    MSG_USERAUTH_REQUEST, MSG_USERAUTH_SUCCESS, MSG_USERAUTH_FAILURE, \
+    MSG_USERAUTH_BANNER, MSG_USERAUTH_INFO_REQUEST, MSG_USERAUTH_INFO_RESPONSE
 
-# this helps freezing utils
-import encodings.utf_8
-
-from paramiko.common import *
-from paramiko import util
 from paramiko.message import Message
+from paramiko.py3compat import bytestring
 from paramiko.ssh_exception import SSHException, AuthenticationException, \
     BadAuthenticationType, PartialAuthentication
 from paramiko.server import InteractiveQuery
@@ -45,6 +48,7 @@ class AuthHandler (object):
         self.authenticated = False
         self.auth_event = None
         self.auth_method = ''
+        self.banner = None
         self.password = None
         self.private_key = None
         self.interactive_handler = None
@@ -113,19 +117,17 @@ class AuthHandler (object):
         if self.auth_event is not None:
             self.auth_event.set()
 
-
     ###  internals...
 
-
     def _request_auth(self):
         m = Message()
-        m.add_byte(chr(MSG_SERVICE_REQUEST))
+        m.add_byte(cMSG_SERVICE_REQUEST)
         m.add_string('ssh-userauth')
         self.transport._send_message(m)
 
     def _disconnect_service_not_available(self):
         m = Message()
-        m.add_byte(chr(MSG_DISCONNECT))
+        m.add_byte(cMSG_DISCONNECT)
         m.add_int(DISCONNECT_SERVICE_NOT_AVAILABLE)
         m.add_string('Service not available')
         m.add_string('en')
@@ -134,7 +136,7 @@ class AuthHandler (object):
 
     def _disconnect_no_more_auth(self):
         m = Message()
-        m.add_byte(chr(MSG_DISCONNECT))
+        m.add_byte(cMSG_DISCONNECT)
         m.add_int(DISCONNECT_NO_MORE_AUTH_METHODS_AVAILABLE)
         m.add_string('No more auth methods available')
         m.add_string('en')
@@ -144,14 +146,14 @@ class AuthHandler (object):
     def _get_session_blob(self, key, service, username):
         m = Message()
         m.add_string(self.transport.session_id)
-        m.add_byte(chr(MSG_USERAUTH_REQUEST))
+        m.add_byte(cMSG_USERAUTH_REQUEST)
         m.add_string(username)
         m.add_string(service)
         m.add_string('publickey')
-        m.add_boolean(1)
+        m.add_boolean(True)
         m.add_string(key.get_name())
-        m.add_string(str(key))
-        return str(m)
+        m.add_string(key)
+        return m.asbytes()
 
     def wait_for_response(self, event):
         while True:
@@ -167,7 +169,7 @@ class AuthHandler (object):
             e = self.transport.get_exception()
             if e is None:
                 e = AuthenticationException('Authentication failed.')
-            # this is horrible.  python Exception isn't yet descended from
+            # this is horrible.  Python Exception isn't yet descended from
             # object, so type(e) won't work. :(
             if issubclass(e.__class__, PartialAuthentication):
                 return e.allowed_types
@@ -175,11 +177,11 @@ class AuthHandler (object):
         return []
 
     def _parse_service_request(self, m):
-        service = m.get_string()
+        service = m.get_text()
         if self.transport.server_mode and (service == 'ssh-userauth'):
             # accepted
             m = Message()
-            m.add_byte(chr(MSG_SERVICE_ACCEPT))
+            m.add_byte(cMSG_SERVICE_ACCEPT)
             m.add_string(service)
             self.transport._send_message(m)
             return
@@ -187,27 +189,25 @@ class AuthHandler (object):
         self._disconnect_service_not_available()
 
     def _parse_service_accept(self, m):
-        service = m.get_string()
+        service = m.get_text()
         if service == 'ssh-userauth':
             self.transport._log(DEBUG, 'userauth is OK')
             m = Message()
-            m.add_byte(chr(MSG_USERAUTH_REQUEST))
+            m.add_byte(cMSG_USERAUTH_REQUEST)
             m.add_string(self.username)
             m.add_string('ssh-connection')
             m.add_string(self.auth_method)
             if self.auth_method == 'password':
                 m.add_boolean(False)
-                password = self.password
-                if isinstance(password, unicode):
-                    password = password.encode('UTF-8')
+                password = bytestring(self.password)
                 m.add_string(password)
             elif self.auth_method == 'publickey':
                 m.add_boolean(True)
                 m.add_string(self.private_key.get_name())
-                m.add_string(str(self.private_key))
+                m.add_string(self.private_key)
                 blob = self._get_session_blob(self.private_key, 'ssh-connection', self.username)
-                sig = self.private_key.sign_ssh_data(self.transport.rng, blob)
-                m.add_string(str(sig))
+                sig = self.private_key.sign_ssh_data(blob)
+                m.add_string(sig)
             elif self.auth_method == 'keyboard-interactive':
                 m.add_string('')
                 m.add_string(self.submethods)
@@ -224,16 +224,16 @@ class AuthHandler (object):
         m = Message()
         if result == AUTH_SUCCESSFUL:
             self.transport._log(INFO, 'Auth granted (%s).' % method)
-            m.add_byte(chr(MSG_USERAUTH_SUCCESS))
+            m.add_byte(cMSG_USERAUTH_SUCCESS)
             self.authenticated = True
         else:
             self.transport._log(INFO, 'Auth rejected (%s).' % method)
-            m.add_byte(chr(MSG_USERAUTH_FAILURE))
+            m.add_byte(cMSG_USERAUTH_FAILURE)
             m.add_string(self.transport.server_object.get_allowed_auths(username))
             if result == AUTH_PARTIALLY_SUCCESSFUL:
-                m.add_boolean(1)
+                m.add_boolean(True)
             else:
-                m.add_boolean(0)
+                m.add_boolean(False)
                 self.auth_fail_count += 1
         self.transport._send_message(m)
         if self.auth_fail_count >= 10:
@@ -244,10 +244,10 @@ class AuthHandler (object):
     def _interactive_query(self, q):
         # make interactive query instead of response
         m = Message()
-        m.add_byte(chr(MSG_USERAUTH_INFO_REQUEST))
+        m.add_byte(cMSG_USERAUTH_INFO_REQUEST)
         m.add_string(q.name)
         m.add_string(q.instructions)
-        m.add_string('')
+        m.add_string(bytes())
         m.add_int(len(q.prompts))
         for p in q.prompts:
             m.add_string(p[0])
@@ -258,17 +258,17 @@ class AuthHandler (object):
         if not self.transport.server_mode:
             # er, uh... what?
             m = Message()
-            m.add_byte(chr(MSG_USERAUTH_FAILURE))
+            m.add_byte(cMSG_USERAUTH_FAILURE)
             m.add_string('none')
-            m.add_boolean(0)
+            m.add_boolean(False)
             self.transport._send_message(m)
             return
         if self.authenticated:
             # ignore
             return
-        username = m.get_string()
-        service = m.get_string()
-        method = m.get_string()
+        username = m.get_text()
+        service = m.get_text()
+        method = m.get_text()
         self.transport._log(DEBUG, 'Auth request (type=%s) service=%s, username=%s' % (method, service, username))
         if service != 'ssh-connection':
             self._disconnect_service_not_available()
@@ -283,7 +283,7 @@ class AuthHandler (object):
             result = self.transport.server_object.check_auth_none(username)
         elif method == 'password':
             changereq = m.get_boolean()
-            password = m.get_string()
+            password = m.get_binary()
             try:
                 password = password.decode('UTF-8')
             except UnicodeError:
@@ -294,7 +294,7 @@ class AuthHandler (object):
                 # always treated as failure, since we don't support changing passwords, but collect
                 # the list of valid auth types from the callback anyway
                 self.transport._log(DEBUG, 'Auth request to change passwords (rejected)')
-                newpassword = m.get_string()
+                newpassword = m.get_binary()
                 try:
                     newpassword = newpassword.decode('UTF-8', 'replace')
                 except UnicodeError:
@@ -304,11 +304,11 @@ class AuthHandler (object):
                 result = self.transport.server_object.check_auth_password(username, password)
         elif method == 'publickey':
             sig_attached = m.get_boolean()
-            keytype = m.get_string()
-            keyblob = m.get_string()
+            keytype = m.get_text()
+            keyblob = m.get_binary()
             try:
                 key = self.transport._key_info[keytype](Message(keyblob))
-            except SSHException, e:
+            except SSHException as e:
                 self.transport._log(INFO, 'Auth rejected: public key: %s' % str(e))
                 key = None
             except:
@@ -325,12 +325,12 @@ class AuthHandler (object):
                     # client wants to know if this key is acceptable, before it
                     # signs anything...  send special "ok" message
                     m = Message()
-                    m.add_byte(chr(MSG_USERAUTH_PK_OK))
+                    m.add_byte(cMSG_USERAUTH_PK_OK)
                     m.add_string(keytype)
                     m.add_string(keyblob)
                     self.transport._send_message(m)
                     return
-                sig = Message(m.get_string())
+                sig = Message(m.get_binary())
                 blob = self._get_session_blob(key, service, username)
                 if not key.verify_ssh_sig(blob, sig):
                     self.transport._log(INFO, 'Auth rejected: invalid signature')
@@ -352,7 +352,7 @@ class AuthHandler (object):
         self.transport._log(INFO, 'Authentication (%s) successful!' % self.auth_method)
         self.authenticated = True
         self.transport._auth_trigger()
-        if self.auth_event != None:
+        if self.auth_event is not None:
             self.auth_event.set()
 
     def _parse_userauth_failure(self, m):
@@ -370,29 +370,30 @@ class AuthHandler (object):
             self.transport._log(INFO, 'Authentication (%s) failed.' % self.auth_method)
         self.authenticated = False
         self.username = None
-        if self.auth_event != None:
+        if self.auth_event is not None:
             self.auth_event.set()
 
     def _parse_userauth_banner(self, m):
         banner = m.get_string()
+        self.banner = banner
         lang = m.get_string()
-        self.transport._log(INFO, 'Auth banner: ' + banner)
+        self.transport._log(INFO, 'Auth banner: %s' % banner)
         # who cares.
     
     def _parse_userauth_info_request(self, m):
         if self.auth_method != 'keyboard-interactive':
             raise SSHException('Illegal info request from server')
-        title = m.get_string()
-        instructions = m.get_string()
-        m.get_string()  # lang
+        title = m.get_text()
+        instructions = m.get_text()
+        m.get_binary()  # lang
         prompts = m.get_int()
         prompt_list = []
         for i in range(prompts):
-            prompt_list.append((m.get_string(), m.get_boolean()))
+            prompt_list.append((m.get_text(), m.get_boolean()))
         response_list = self.interactive_handler(title, instructions, prompt_list)
         
         m = Message()
-        m.add_byte(chr(MSG_USERAUTH_INFO_RESPONSE))
+        m.add_byte(cMSG_USERAUTH_INFO_RESPONSE)
         m.add_int(len(response_list))
         for r in response_list:
             m.add_string(r)
@@ -404,14 +405,13 @@ class AuthHandler (object):
         n = m.get_int()
         responses = []
         for i in range(n):
-            responses.append(m.get_string())
+            responses.append(m.get_text())
         result = self.transport.server_object.check_auth_interactive_response(responses)
         if isinstance(type(result), InteractiveQuery):
             # make interactive query instead of response
             self._interactive_query(result)
             return
         self._send_auth_result(self.auth_username, 'keyboard-interactive', result)
-        
 
     _handler_table = {
         MSG_SERVICE_REQUEST: _parse_service_request,
@@ -423,4 +423,3 @@ class AuthHandler (object):
         MSG_USERAUTH_INFO_REQUEST: _parse_userauth_info_request,
         MSG_USERAUTH_INFO_RESPONSE: _parse_userauth_info_response,
     }
-
diff --git a/paramiko/ber.py b/paramiko/ber.py
index 3941581..0515230 100644
--- a/paramiko/ber.py
+++ b/paramiko/ber.py
@@ -15,9 +15,10 @@
 # You should have received a copy of the GNU Lesser General Public License
 # along with Paramiko; if not, write to the Free Software Foundation, Inc.,
 # 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA.
+from paramiko.common import max_byte, zero_byte
+from paramiko.py3compat import b, byte_ord, byte_chr, long
 
-
-import util
+import paramiko.util as util
 
 
 class BERException (Exception):
@@ -29,13 +30,16 @@ class BER(object):
     Robey's tiny little attempt at a BER decoder.
     """
 
-    def __init__(self, content=''):
-        self.content = content
+    def __init__(self, content=bytes()):
+        self.content = b(content)
         self.idx = 0
 
-    def __str__(self):
+    def asbytes(self):
         return self.content
 
+    def __str__(self):
+        return self.asbytes()
+
     def __repr__(self):
         return 'BER(\'' + repr(self.content) + '\')'
 
@@ -45,13 +49,13 @@ class BER(object):
     def decode_next(self):
         if self.idx >= len(self.content):
             return None
-        ident = ord(self.content[self.idx])
+        ident = byte_ord(self.content[self.idx])
         self.idx += 1
         if (ident & 31) == 31:
             # identifier > 30
             ident = 0
             while self.idx < len(self.content):
-                t = ord(self.content[self.idx])
+                t = byte_ord(self.content[self.idx])
                 self.idx += 1
                 ident = (ident << 7) | (t & 0x7f)
                 if not (t & 0x80):
@@ -59,7 +63,7 @@ class BER(object):
         if self.idx >= len(self.content):
             return None
         # now fetch length
-        size = ord(self.content[self.idx])
+        size = byte_ord(self.content[self.idx])
         self.idx += 1
         if size & 0x80:
             # more complimicated...
@@ -67,12 +71,12 @@ class BER(object):
             t = size & 0x7f
             if self.idx + t > len(self.content):
                 return None
-            size = util.inflate_long(self.content[self.idx : self.idx + t], True)
+            size = util.inflate_long(self.content[self.idx: self.idx + t], True)
             self.idx += t
         if self.idx + size > len(self.content):
             # can't fit
             return None
-        data = self.content[self.idx : self.idx + size]
+        data = self.content[self.idx: self.idx + size]
         self.idx += size
         # now switch on id
         if ident == 0x30:
@@ -87,9 +91,9 @@ class BER(object):
 
     def decode_sequence(data):
         out = []
-        b = BER(data)
+        ber = BER(data)
         while True:
-            x = b.decode_next()
+            x = ber.decode_next()
             if x is None:
                 break
             out.append(x)
@@ -98,20 +102,20 @@ class BER(object):
 
     def encode_tlv(self, ident, val):
         # no need to support ident > 31 here
-        self.content += chr(ident)
+        self.content += byte_chr(ident)
         if len(val) > 0x7f:
             lenstr = util.deflate_long(len(val))
-            self.content += chr(0x80 + len(lenstr)) + lenstr
+            self.content += byte_chr(0x80 + len(lenstr)) + lenstr
         else:
-            self.content += chr(len(val))
+            self.content += byte_chr(len(val))
         self.content += val
 
     def encode(self, x):
         if type(x) is bool:
             if x:
-                self.encode_tlv(1, '\xff')
+                self.encode_tlv(1, max_byte)
             else:
-                self.encode_tlv(1, '\x00')
+                self.encode_tlv(1, zero_byte)
         elif (type(x) is int) or (type(x) is long):
             self.encode_tlv(2, util.deflate_long(x))
         elif type(x) is str:
@@ -122,8 +126,8 @@ class BER(object):
             raise BERException('Unknown type for encoding: %s' % repr(type(x)))
 
     def encode_sequence(data):
-        b = BER()
+        ber = BER()
         for item in data:
-            b.encode(item)
-        return str(b)
+            ber.encode(item)
+        return ber.asbytes()
     encode_sequence = staticmethod(encode_sequence)
diff --git a/paramiko/buffered_pipe.py b/paramiko/buffered_pipe.py
index 4ef5cf7..ac35b3e 100644
--- a/paramiko/buffered_pipe.py
+++ b/paramiko/buffered_pipe.py
@@ -17,7 +17,7 @@
 # 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA.
 
 """
-Attempt to generalize the "feeder" part of a Channel: an object which can be
+Attempt to generalize the "feeder" part of a `.Channel`: an object which can be
 read from and closed, but is reading from a buffer fed by another thread.  The
 read operations are blocking and can have a timeout set.
 """
@@ -25,11 +25,12 @@ read operations are blocking and can have a timeout set.
 import array
 import threading
 import time
+from paramiko.py3compat import PY2, b
 
 
 class PipeTimeout (IOError):
     """
-    Indicates that a timeout was reached on a read from a L{BufferedPipe}.
+    Indicates that a timeout was reached on a read from a `.BufferedPipe`.
     """
     pass
 
@@ -38,7 +39,7 @@ class BufferedPipe (object):
     """
     A buffer that obeys normal read (with timeout) & close semantics for a
     file or socket, but is fed data from another thread.  This is used by
-    L{Channel}.
+    `.Channel`.
     """
     
     def __init__(self):
@@ -48,14 +49,26 @@ class BufferedPipe (object):
         self._buffer = array.array('B')
         self._closed = False
 
+    if PY2:
+        def _buffer_frombytes(self, data):
+            self._buffer.fromstring(data)
+
+        def _buffer_tobytes(self, limit=None):
+            return self._buffer[:limit].tostring()
+    else:
+        def _buffer_frombytes(self, data):
+            self._buffer.frombytes(data)
+
+        def _buffer_tobytes(self, limit=None):
+            return self._buffer[:limit].tobytes()
+
     def set_event(self, event):
         """
         Set an event on this buffer.  When data is ready to be read (or the
         buffer has been closed), the event will be set.  When no data is
         ready, the event will be cleared.
         
-        @param event: the event to set/clear
-        @type event: Event
+        :param threading.Event event: the event to set/clear
         """
         self._event = event
         if len(self._buffer) > 0:
@@ -68,14 +81,13 @@ class BufferedPipe (object):
         Feed new data into this pipe.  This method is assumed to be called
         from a separate thread, so synchronization is done.
         
-        @param data: the data to add
-        @type data: str
+        :param data: the data to add, as a `str`
         """
         self._lock.acquire()
         try:
             if self._event is not None:
                 self._event.set()
-            self._buffer.fromstring(data)
+            self._buffer_frombytes(b(data))
             self._cv.notifyAll()
         finally:
             self._lock.release()
@@ -83,12 +95,12 @@ class BufferedPipe (object):
     def read_ready(self):
         """
         Returns true if data is buffered and ready to be read from this
-        feeder.  A C{False} result does not mean that the feeder has closed;
+        feeder.  A ``False`` result does not mean that the feeder has closed;
         it means you may need to wait before more data arrives.
         
-        @return: C{True} if a L{read} call would immediately return at least
-            one byte; C{False} otherwise.
-        @rtype: bool
+        :return:
+            ``True`` if a `read` call would immediately return at least one
+            byte; ``False`` otherwise.
         """
         self._lock.acquire()
         try:
@@ -102,26 +114,24 @@ class BufferedPipe (object):
         """
         Read data from the pipe.  The return value is a string representing
         the data received.  The maximum amount of data to be received at once
-        is specified by C{nbytes}.  If a string of length zero is returned,
+        is specified by ``nbytes``.  If a string of length zero is returned,
         the pipe has been closed.
 
-        The optional C{timeout} argument can be a nonnegative float expressing
-        seconds, or C{None} for no timeout.  If a float is given, a
-        C{PipeTimeout} will be raised if the timeout period value has
-        elapsed before any data arrives.
-
-        @param nbytes: maximum number of bytes to read
-        @type nbytes: int
-        @param timeout: maximum seconds to wait (or C{None}, the default, to
-            wait forever)
-        @type timeout: float
-        @return: data
-        @rtype: str
+        The optional ``timeout`` argument can be a nonnegative float expressing
+        seconds, or ``None`` for no timeout.  If a float is given, a
+        `.PipeTimeout` will be raised if the timeout period value has elapsed
+        before any data arrives.
+
+        :param int nbytes: maximum number of bytes to read
+        :param float timeout:
+            maximum seconds to wait (or ``None``, the default, to wait forever)
+        :return: the read data, as a `str`
         
-        @raise PipeTimeout: if a timeout was specified and no data was ready
-            before that timeout
+        :raises PipeTimeout:
+            if a timeout was specified and no data was ready before that
+            timeout
         """
-        out = ''
+        out = bytes()
         self._lock.acquire()
         try:
             if len(self._buffer) == 0:
@@ -142,12 +152,12 @@ class BufferedPipe (object):
 
             # something's in the buffer and we have the lock!
             if len(self._buffer) <= nbytes:
-                out = self._buffer.tostring()
+                out = self._buffer_tobytes()
                 del self._buffer[:]
                 if (self._event is not None) and not self._closed:
                     self._event.clear()
             else:
-                out = self._buffer[:nbytes].tostring()
+                out = self._buffer_tobytes(nbytes)
                 del self._buffer[:nbytes]
         finally:
             self._lock.release()
@@ -158,12 +168,13 @@ class BufferedPipe (object):
         """
         Clear out the buffer and return all data that was in it.
         
-        @return: any data that was in the buffer prior to clearing it out
-        @rtype: str
+        :return:
+            any data that was in the buffer prior to clearing it out, as a
+            `str`
         """
         self._lock.acquire()
         try:
-            out = self._buffer.tostring()
+            out = self._buffer_tobytes()
             del self._buffer[:]
             if (self._event is not None) and not self._closed:
                 self._event.clear()
@@ -173,7 +184,7 @@ class BufferedPipe (object):
     
     def close(self):
         """
-        Close this pipe object.  Future calls to L{read} after the buffer
+        Close this pipe object.  Future calls to `read` after the buffer
         has been emptied will return immediately with an empty string.
         """
         self._lock.acquire()
@@ -189,12 +200,10 @@ class BufferedPipe (object):
         """
         Return the number of bytes buffered.
         
-        @return: number of bytes bufferes
-        @rtype: int
+        :return: number (`int`) of bytes buffered
         """
         self._lock.acquire()
         try:
             return len(self._buffer)
         finally:
             self._lock.release()
-
diff --git a/paramiko/channel.py b/paramiko/channel.py
index d1e6333..583809d 100644
--- a/paramiko/channel.py
+++ b/paramiko/channel.py
@@ -21,15 +21,18 @@ Abstraction for an SSH2 channel.
 """
 
 import binascii
-import sys
+import os
+import socket
 import time
 import threading
-import socket
-import os
 
-from paramiko.common import *
 from paramiko import util
+from paramiko.common import cMSG_CHANNEL_REQUEST, cMSG_CHANNEL_WINDOW_ADJUST, \
+    cMSG_CHANNEL_DATA, cMSG_CHANNEL_EXTENDED_DATA, DEBUG, ERROR, \
+    cMSG_CHANNEL_SUCCESS, cMSG_CHANNEL_FAILURE, cMSG_CHANNEL_EOF, \
+    cMSG_CHANNEL_CLOSE
 from paramiko.message import Message
+from paramiko.py3compat import bytes_types
 from paramiko.ssh_exception import SSHException
 from paramiko.file import BufferedFile
 from paramiko.buffered_pipe import BufferedPipe, PipeTimeout
@@ -42,29 +45,28 @@ MIN_PACKET_SIZE = 1024
 
 class Channel (object):
     """
-    A secure tunnel across an SSH L{Transport}.  A Channel is meant to behave
+    A secure tunnel across an SSH `.Transport`.  A Channel is meant to behave
     like a socket, and has an API that should be indistinguishable from the
-    python socket API.
+    Python socket API.
 
     Because SSH2 has a windowing kind of flow control, if you stop reading data
     from a Channel and its buffer fills up, the server will be unable to send
     you any more data until you read some of it.  (This won't affect other
     channels on the same transport -- all channels on a single transport are
     flow-controlled independently.)  Similarly, if the server isn't reading
-    data you send, calls to L{send} may block, unless you set a timeout.  This
+    data you send, calls to `send` may block, unless you set a timeout.  This
     is exactly like a normal network socket, so it shouldn't be too surprising.
     """
 
     def __init__(self, chanid):
         """
         Create a new channel.  The channel is not associated with any
-        particular session or L{Transport} until the Transport attaches it.
+        particular session or `.Transport` until the Transport attaches it.
         Normally you would only call this method from the constructor of a
-        subclass of L{Channel}.
+        subclass of `.Channel`.
 
-        @param chanid: the ID of this channel, as passed by an existing
-            L{Transport}.
-        @type chanid: int
+        :param int chanid:
+            the ID of this channel, as passed by an existing `.Transport`.
         """
         self.chanid = chanid
         self.remote_chanid = 0
@@ -104,8 +106,6 @@ class Channel (object):
     def __repr__(self):
         """
         Return a string representation of this object, for debugging.
-
-        @rtype: str
         """
         out = '<paramiko.Channel %d' % self.chanid
         if self.closed:
@@ -115,7 +115,7 @@ class Channel (object):
                 out += ' (EOF received)'
             if self.eof_sent:
                 out += ' (EOF sent)'
-            out += ' (open) window=%d' % (self.out_window_size)
+            out += ' (open) window=%d' % self.out_window_size
             if len(self.in_buffer) > 0:
                 out += ' in-buffer=%d' % (len(self.in_buffer),)
         out += ' -> ' + repr(self.transport)
@@ -127,28 +127,23 @@ class Channel (object):
         """
         Request a pseudo-terminal from the server.  This is usually used right
         after creating a client channel, to ask the server to provide some
-        basic terminal semantics for a shell invoked with L{invoke_shell}.
+        basic terminal semantics for a shell invoked with `invoke_shell`.
         It isn't necessary (or desirable) to call this method if you're going
-        to exectue a single command with L{exec_command}.
-
-        @param term: the terminal type to emulate (for example, C{'vt100'})
-        @type term: str
-        @param width: width (in characters) of the terminal screen
-        @type width: int
-        @param height: height (in characters) of the terminal screen
-        @type height: int
-        @param width_pixels: width (in pixels) of the terminal screen
-        @type width_pixels: int
-        @param height_pixels: height (in pixels) of the terminal screen
-        @type height_pixels: int
+        to exectue a single command with `exec_command`.
+
+        :param str term: the terminal type to emulate (for example, ``'vt100'``)
+        :param int width: width (in characters) of the terminal screen
+        :param int height: height (in characters) of the terminal screen
+        :param int width_pixels: width (in pixels) of the terminal screen
+        :param int height_pixels: height (in pixels) of the terminal screen
         
-        @raise SSHException: if the request was rejected or the channel was
-            closed
+        :raises SSHException:
+            if the request was rejected or the channel was closed
         """
         if self.closed or self.eof_received or self.eof_sent or not self.active:
             raise SSHException('Channel is not open')
         m = Message()
-        m.add_byte(chr(MSG_CHANNEL_REQUEST))
+        m.add_byte(cMSG_CHANNEL_REQUEST)
         m.add_int(self.remote_chanid)
         m.add_string('pty-req')
         m.add_boolean(True)
@@ -157,7 +152,7 @@ class Channel (object):
         m.add_int(height)
         m.add_int(width_pixels)
         m.add_int(height_pixels)
-        m.add_string('')
+        m.add_string(bytes())
         self._event_pending()
         self.transport._send_user_message(m)
         self._wait_for_event()
@@ -168,23 +163,23 @@ class Channel (object):
         allows it, the channel will then be directly connected to the stdin,
         stdout, and stderr of the shell.
         
-        Normally you would call L{get_pty} before this, in which case the
+        Normally you would call `get_pty` before this, in which case the
         shell will operate through the pty, and the channel will be connected
         to the stdin and stdout of the pty.
         
         When the shell exits, the channel will be closed and can't be reused.
         You must open a new channel if you wish to open another shell.
         
-        @raise SSHException: if the request was rejected or the channel was
+        :raises SSHException: if the request was rejected or the channel was
             closed
         """
         if self.closed or self.eof_received or self.eof_sent or not self.active:
             raise SSHException('Channel is not open')
         m = Message()
-        m.add_byte(chr(MSG_CHANNEL_REQUEST))
+        m.add_byte(cMSG_CHANNEL_REQUEST)
         m.add_int(self.remote_chanid)
         m.add_string('shell')
-        m.add_boolean(1)
+        m.add_boolean(True)
         self._event_pending()
         self.transport._send_user_message(m)
         self._wait_for_event()
@@ -199,16 +194,15 @@ class Channel (object):
         can't be reused.  You must open a new channel if you wish to execute
         another command.
 
-        @param command: a shell command to execute.
-        @type command: str
+        :param str command: a shell command to execute.
 
-        @raise SSHException: if the request was rejected or the channel was
+        :raises SSHException: if the request was rejected or the channel was
             closed
         """
         if self.closed or self.eof_received or self.eof_sent or not self.active:
             raise SSHException('Channel is not open')
         m = Message()
-        m.add_byte(chr(MSG_CHANNEL_REQUEST))
+        m.add_byte(cMSG_CHANNEL_REQUEST)
         m.add_int(self.remote_chanid)
         m.add_string('exec')
         m.add_boolean(True)
@@ -219,23 +213,22 @@ class Channel (object):
 
     def invoke_subsystem(self, subsystem):
         """
-        Request a subsystem on the server (for example, C{sftp}).  If the
+        Request a subsystem on the server (for example, ``sftp``).  If the
         server allows it, the channel will then be directly connected to the
         requested subsystem.
         
         When the subsystem finishes, the channel will be closed and can't be
         reused.
 
-        @param subsystem: name of the subsystem being requested.
-        @type subsystem: str
+        :param str subsystem: name of the subsystem being requested.
 
-        @raise SSHException: if the request was rejected or the channel was
-            closed
+        :raises SSHException:
+            if the request was rejected or the channel was closed
         """
         if self.closed or self.eof_received or self.eof_sent or not self.active:
             raise SSHException('Channel is not open')
         m = Message()
-        m.add_byte(chr(MSG_CHANNEL_REQUEST))
+        m.add_byte(cMSG_CHANNEL_REQUEST)
         m.add_int(self.remote_chanid)
         m.add_string('subsystem')
         m.add_boolean(True)
@@ -247,24 +240,20 @@ class Channel (object):
     def resize_pty(self, width=80, height=24, width_pixels=0, height_pixels=0):
         """
         Resize the pseudo-terminal.  This can be used to change the width and
-        height of the terminal emulation created in a previous L{get_pty} call.
-
-        @param width: new width (in characters) of the terminal screen
-        @type width: int
-        @param height: new height (in characters) of the terminal screen
-        @type height: int
-        @param width_pixels: new width (in pixels) of the terminal screen
-        @type width_pixels: int
-        @param height_pixels: new height (in pixels) of the terminal screen
-        @type height_pixels: int
-
-        @raise SSHException: if the request was rejected or the channel was
-            closed
+        height of the terminal emulation created in a previous `get_pty` call.
+
+        :param int width: new width (in characters) of the terminal screen
+        :param int height: new height (in characters) of the terminal screen
+        :param int width_pixels: new width (in pixels) of the terminal screen
+        :param int height_pixels: new height (in pixels) of the terminal screen
+
+        :raises SSHException:
+            if the request was rejected or the channel was closed
         """
         if self.closed or self.eof_received or self.eof_sent or not self.active:
             raise SSHException('Channel is not open')
         m = Message()
-        m.add_byte(chr(MSG_CHANNEL_REQUEST))
+        m.add_byte(cMSG_CHANNEL_REQUEST)
         m.add_int(self.remote_chanid)
         m.add_string('window-change')
         m.add_boolean(False)
@@ -278,27 +267,27 @@ class Channel (object):
         """
         Return true if the remote process has exited and returned an exit
         status. You may use this to poll the process status if you don't
-        want to block in L{recv_exit_status}. Note that the server may not
+        want to block in `recv_exit_status`. Note that the server may not
         return an exit status in some cases (like bad servers).
         
-        @return: True if L{recv_exit_status} will return immediately
-        @rtype: bool
-        @since: 1.7.3
+        :return:
+            ``True`` if `recv_exit_status` will return immediately, else ``False``.
+
+        .. versionadded:: 1.7.3
         """
         return self.closed or self.status_event.isSet()
         
     def recv_exit_status(self):
         """
         Return the exit status from the process on the server.  This is
-        mostly useful for retrieving the reults of an L{exec_command}.
+        mostly useful for retrieving the reults of an `exec_command`.
         If the command hasn't finished yet, this method will wait until
         it does, or until the channel is closed.  If no exit status is
         provided by the server, -1 is returned.
         
-        @return: the exit code of the process on the server.
-        @rtype: int
+        :return: the exit code (as an `int`) of the process on the server.
         
-        @since: 1.2
+        .. versionadded:: 1.2
         """
         self.status_event.wait()
         assert self.status_event.isSet()
@@ -311,15 +300,14 @@ class Channel (object):
         get some sort of status code back from an executed command after
         it completes.
         
-        @param status: the exit code of the process
-        @type status: int
+        :param int status: the exit code of the process
         
-        @since: 1.2
+        .. versionadded:: 1.2
         """
         # in many cases, the channel will not still be open here.
         # that's fine.
         m = Message()
-        m.add_byte(chr(MSG_CHANNEL_REQUEST))
+        m.add_byte(cMSG_CHANNEL_REQUEST)
         m.add_int(self.remote_chanid)
         m.add_string('exit-status')
         m.add_boolean(False)
@@ -347,35 +335,34 @@ class Channel (object):
         If a handler is passed in, the handler is called from another thread
         whenever a new x11 connection arrives.  The default handler queues up
         incoming x11 connections, which may be retrieved using
-        L{Transport.accept}.  The handler's calling signature is::
+        `.Transport.accept`.  The handler's calling signature is::
         
             handler(channel: Channel, (address: str, port: int))
         
-        @param screen_number: the x11 screen number (0, 10, etc)
-        @type screen_number: int
-        @param auth_protocol: the name of the X11 authentication method used;
-            if none is given, C{"MIT-MAGIC-COOKIE-1"} is used
-        @type auth_protocol: str
-        @param auth_cookie: hexadecimal string containing the x11 auth cookie;
-            if none is given, a secure random 128-bit value is generated
-        @type auth_cookie: str
-        @param single_connection: if True, only a single x11 connection will be
-            forwarded (by default, any number of x11 connections can arrive
-            over this session)
-        @type single_connection: bool
-        @param handler: an optional handler to use for incoming X11 connections
-        @type handler: function
-        @return: the auth_cookie used
+        :param int screen_number: the x11 screen number (0, 10, etc)
+        :param str auth_protocol:
+            the name of the X11 authentication method used; if none is given,
+            ``"MIT-MAGIC-COOKIE-1"`` is used
+        :param str auth_cookie:
+            hexadecimal string containing the x11 auth cookie; if none is
+            given, a secure random 128-bit value is generated
+        :param bool single_connection:
+            if True, only a single x11 connection will be forwarded (by
+            default, any number of x11 connections can arrive over this
+            session)
+        :param function handler:
+            an optional handler to use for incoming X11 connections
+        :return: the auth_cookie used
         """
         if self.closed or self.eof_received or self.eof_sent or not self.active:
             raise SSHException('Channel is not open')
         if auth_protocol is None:
             auth_protocol = 'MIT-MAGIC-COOKIE-1'
         if auth_cookie is None:
-            auth_cookie = binascii.hexlify(self.transport.rng.read(16))
+            auth_cookie = binascii.hexlify(os.urandom(16))
 
         m = Message()
-        m.add_byte(chr(MSG_CHANNEL_REQUEST))
+        m.add_byte(cMSG_CHANNEL_REQUEST)
         m.add_int(self.remote_chanid)
         m.add_string('x11-req')
         m.add_boolean(True)
@@ -392,21 +379,20 @@ class Channel (object):
     def request_forward_agent(self, handler):
         """
         Request for a forward SSH Agent on this channel.
-        This is only valid for an ssh-agent from openssh !!!
+        This is only valid for an ssh-agent from OpenSSH !!!
 
-        @param handler: a required handler to use for incoming SSH Agent connections
-        @type handler: function
+        :param function handler:
+            a required handler to use for incoming SSH Agent connections
 
-        @return: if we are ok or not (at that time we always return ok)
-        @rtype: boolean
+        :return: True if we are ok, else False (at that time we always return ok)
 
-        @raise: SSHException in case of channel problem.
+        :raises: SSHException in case of channel problem.
         """
         if self.closed or self.eof_received or self.eof_sent or not self.active:
             raise SSHException('Channel is not open')
 
         m = Message()
-        m.add_byte(chr(MSG_CHANNEL_REQUEST))
+        m.add_byte(cMSG_CHANNEL_REQUEST)
         m.add_int(self.remote_chanid)
         m.add_string('auth-agent-req@openssh.com')
         m.add_boolean(False)
@@ -416,10 +402,7 @@ class Channel (object):
 
     def get_transport(self):
         """
-        Return the L{Transport} associated with this channel.
-
-        @return: the L{Transport} that was used to create this channel.
-        @rtype: L{Transport}
+        Return the `.Transport` associated with this channel.
         """
         return self.transport
 
@@ -427,57 +410,51 @@ class Channel (object):
         """
         Set a name for this channel.  Currently it's only used to set the name
         of the channel in logfile entries.  The name can be fetched with the
-        L{get_name} method.
+        `get_name` method.
 
-        @param name: new channel name
-        @type name: str
+        :param str name: new channel name
         """
         self._name = name
 
     def get_name(self):
         """
-        Get the name of this channel that was previously set by L{set_name}.
-
-        @return: the name of this channel.
-        @rtype: str
+        Get the name of this channel that was previously set by `set_name`.
         """
         return self._name
 
     def get_id(self):
         """
-        Return the ID # for this channel.  The channel ID is unique across
-        a L{Transport} and usually a small number.  It's also the number
-        passed to L{ServerInterface.check_channel_request} when determining
-        whether to accept a channel request in server mode.
-
-        @return: the ID of this channel.
-        @rtype: int
+        Return the `int` ID # for this channel.
+        
+        The channel ID is unique across a `.Transport` and usually a small
+        number.  It's also the number passed to
+        `.ServerInterface.check_channel_request` when determining whether to
+        accept a channel request in server mode.
         """
         return self.chanid
     
     def set_combine_stderr(self, combine):
         """
         Set whether stderr should be combined into stdout on this channel.
-        The default is C{False}, but in some cases it may be convenient to
+        The default is ``False``, but in some cases it may be convenient to
         have both streams combined.
         
-        If this is C{False}, and L{exec_command} is called (or C{invoke_shell}
-        with no pty), output to stderr will not show up through the L{recv}
-        and L{recv_ready} calls.  You will have to use L{recv_stderr} and
-        L{recv_stderr_ready} to get stderr output.
+        If this is ``False``, and `exec_command` is called (or ``invoke_shell``
+        with no pty), output to stderr will not show up through the `recv`
+        and `recv_ready` calls.  You will have to use `recv_stderr` and
+        `recv_stderr_ready` to get stderr output.
         
-        If this is C{True}, data will never show up via L{recv_stderr} or
-        L{recv_stderr_ready}.
+        If this is ``True``, data will never show up via `recv_stderr` or
+        `recv_stderr_ready`.
         
-        @param combine: C{True} if stderr output should be combined into
-            stdout on this channel.
-        @type combine: bool
-        @return: previous setting.
-        @rtype: bool
+        :param bool combine:
+            ``True`` if stderr output should be combined into stdout on this
+            channel.
+        :return: the previous setting (a `bool`).
         
-        @since: 1.1
+        .. versionadded:: 1.1
         """
-        data = ''
+        data = bytes()
         self.lock.acquire()
         try:
             old = self.combine_stderr
@@ -491,57 +468,51 @@ class Channel (object):
             self._feed(data)
         return old
 
-    
     ###  socket API
 
-
     def settimeout(self, timeout):
         """
-        Set a timeout on blocking read/write operations.  The C{timeout}
-        argument can be a nonnegative float expressing seconds, or C{None}.  If
+        Set a timeout on blocking read/write operations.  The ``timeout``
+        argument can be a nonnegative float expressing seconds, or ``None``.  If
         a float is given, subsequent channel read/write operations will raise
         a timeout exception if the timeout period value has elapsed before the
-        operation has completed.  Setting a timeout of C{None} disables
+        operation has completed.  Setting a timeout of ``None`` disables
         timeouts on socket operations.
 
-        C{chan.settimeout(0.0)} is equivalent to C{chan.setblocking(0)};
-        C{chan.settimeout(None)} is equivalent to C{chan.setblocking(1)}.
+        ``chan.settimeout(0.0)`` is equivalent to ``chan.setblocking(0)``;
+        ``chan.settimeout(None)`` is equivalent to ``chan.setblocking(1)``.
 
-        @param timeout: seconds to wait for a pending read/write operation
-            before raising C{socket.timeout}, or C{None} for no timeout.
-        @type timeout: float
+        :param float timeout:
+            seconds to wait for a pending read/write operation before raising
+            ``socket.timeout``, or ``None`` for no timeout.
         """
         self.timeout = timeout
 
     def gettimeout(self):
         """
         Returns the timeout in seconds (as a float) associated with socket
-        operations, or C{None} if no timeout is set.  This reflects the last
-        call to L{setblocking} or L{settimeout}.
-
-        @return: timeout in seconds, or C{None}.
-        @rtype: float
+        operations, or ``None`` if no timeout is set.  This reflects the last
+        call to `setblocking` or `settimeout`.
         """
         return self.timeout
 
     def setblocking(self, blocking):
         """
-        Set blocking or non-blocking mode of the channel: if C{blocking} is 0,
+        Set blocking or non-blocking mode of the channel: if ``blocking`` is 0,
         the channel is set to non-blocking mode; otherwise it's set to blocking
         mode. Initially all channels are in blocking mode.
 
-        In non-blocking mode, if a L{recv} call doesn't find any data, or if a
-        L{send} call can't immediately dispose of the data, an error exception
+        In non-blocking mode, if a `recv` call doesn't find any data, or if a
+        `send` call can't immediately dispose of the data, an error exception
         is raised. In blocking mode, the calls block until they can proceed. An
-        EOF condition is considered "immediate data" for L{recv}, so if the
+        EOF condition is considered "immediate data" for `recv`, so if the
         channel is closed in the read direction, it will never block.
 
-        C{chan.setblocking(0)} is equivalent to C{chan.settimeout(0)};
-        C{chan.setblocking(1)} is equivalent to C{chan.settimeout(None)}.
+        ``chan.setblocking(0)`` is equivalent to ``chan.settimeout(0)``;
+        ``chan.setblocking(1)`` is equivalent to ``chan.settimeout(None)``.
 
-        @param blocking: 0 to set non-blocking mode; non-0 to set blocking
-            mode.
-        @type blocking: int
+        :param int blocking:
+            0 to set non-blocking mode; non-0 to set blocking mode.
         """
         if blocking:
             self.settimeout(None)
@@ -551,12 +522,10 @@ class Channel (object):
     def getpeername(self):
         """
         Return the address of the remote side of this Channel, if possible.
-        This is just a wrapper around C{'getpeername'} on the Transport, used
-        to provide enough of a socket-like interface to allow asyncore to work.
-        (asyncore likes to call C{'getpeername'}.)
 
-        @return: the address if the remote host, if known
-        @rtype: tuple(str, int)
+        This simply wraps `.Transport.getpeername`, used to provide enough of a
+        socket-like interface to allow asyncore to work. (asyncore likes to
+        call ``'getpeername'``.)
         """
         return self.transport.getpeername()
 
@@ -564,7 +533,7 @@ class Channel (object):
         """
         Close the channel.  All future read/write operations on the channel
         will fail.  The remote end will receive no more data (after queued data
-        is flushed).  Channels are automatically closed when their L{Transport}
+        is flushed).  Channels are automatically closed when their `.Transport`
         is closed or when they are garbage collected.
         """
         self.lock.acquire()
@@ -589,12 +558,12 @@ class Channel (object):
     def recv_ready(self):
         """
         Returns true if data is buffered and ready to be read from this
-        channel.  A C{False} result does not mean that the channel has closed;
+        channel.  A ``False`` result does not mean that the channel has closed;
         it means you may need to wait before more data arrives.
         
-        @return: C{True} if a L{recv} call on this channel would immediately
-            return at least one byte; C{False} otherwise.
-        @rtype: boolean
+        :return:
+            ``True`` if a `recv` call on this channel would immediately return
+            at least one byte; ``False`` otherwise.
         """
         return self.in_buffer.read_ready()
 
@@ -602,27 +571,25 @@ class Channel (object):
         """
         Receive data from the channel.  The return value is a string
         representing the data received.  The maximum amount of data to be
-        received at once is specified by C{nbytes}.  If a string of length zero
+        received at once is specified by ``nbytes``.  If a string of length zero
         is returned, the channel stream has closed.
 
-        @param nbytes: maximum number of bytes to read.
-        @type nbytes: int
-        @return: data.
-        @rtype: str
+        :param int nbytes: maximum number of bytes to read.
+        :return: received data, as a `str`
         
-        @raise socket.timeout: if no data is ready before the timeout set by
-            L{settimeout}.
+        :raises socket.timeout:
+            if no data is ready before the timeout set by `settimeout`.
         """
         try:
             out = self.in_buffer.read(nbytes, self.timeout)
-        except PipeTimeout, e:
+        except PipeTimeout:
             raise socket.timeout()
 
         ack = self._check_add_window(len(out))
         # no need to hold the channel lock when sending this
         if ack > 0:
             m = Message()
-            m.add_byte(chr(MSG_CHANNEL_WINDOW_ADJUST))
+            m.add_byte(cMSG_CHANNEL_WINDOW_ADJUST)
             m.add_int(self.remote_chanid)
             m.add_int(ack)
             self.transport._send_user_message(m)
@@ -632,47 +599,45 @@ class Channel (object):
     def recv_stderr_ready(self):
         """
         Returns true if data is buffered and ready to be read from this
-        channel's stderr stream.  Only channels using L{exec_command} or
-        L{invoke_shell} without a pty will ever have data on the stderr
+        channel's stderr stream.  Only channels using `exec_command` or
+        `invoke_shell` without a pty will ever have data on the stderr
         stream.
         
-        @return: C{True} if a L{recv_stderr} call on this channel would
-            immediately return at least one byte; C{False} otherwise.
-        @rtype: boolean
+        :return:
+            ``True`` if a `recv_stderr` call on this channel would immediately
+            return at least one byte; ``False`` otherwise.
         
-        @since: 1.1
+        .. versionadded:: 1.1
         """
         return self.in_stderr_buffer.read_ready()
 
     def recv_stderr(self, nbytes):
         """
         Receive data from the channel's stderr stream.  Only channels using
-        L{exec_command} or L{invoke_shell} without a pty will ever have data
+        `exec_command` or `invoke_shell` without a pty will ever have data
         on the stderr stream.  The return value is a string representing the
         data received.  The maximum amount of data to be received at once is
-        specified by C{nbytes}.  If a string of length zero is returned, the
+        specified by ``nbytes``.  If a string of length zero is returned, the
         channel stream has closed.
 
-        @param nbytes: maximum number of bytes to read.
-        @type nbytes: int
-        @return: data.
-        @rtype: str
+        :param int nbytes: maximum number of bytes to read.
+        :return: received data as a `str`
         
-        @raise socket.timeout: if no data is ready before the timeout set by
-            L{settimeout}.
+        :raises socket.timeout: if no data is ready before the timeout set by
+            `settimeout`.
         
-        @since: 1.1
+        .. versionadded:: 1.1
         """
         try:
             out = self.in_stderr_buffer.read(nbytes, self.timeout)
-        except PipeTimeout, e:
+        except PipeTimeout:
             raise socket.timeout()
             
         ack = self._check_add_window(len(out))
         # no need to hold the channel lock when sending this
         if ack > 0:
             m = Message()
-            m.add_byte(chr(MSG_CHANNEL_WINDOW_ADJUST))
+            m.add_byte(cMSG_CHANNEL_WINDOW_ADJUST)
             m.add_int(self.remote_chanid)
             m.add_int(ack)
             self.transport._send_user_message(m)
@@ -685,12 +650,12 @@ class Channel (object):
         This means the channel is either closed (so any write attempt would
         return immediately) or there is at least one byte of space in the 
         outbound buffer. If there is at least one byte of space in the
-        outbound buffer, a L{send} call will succeed immediately and return
+        outbound buffer, a `send` call will succeed immediately and return
         the number of bytes actually written.
         
-        @return: C{True} if a L{send} call on this channel would immediately
-            succeed or fail
-        @rtype: boolean
+        :return:
+            ``True`` if a `send` call on this channel would immediately succeed
+            or fail
         """
         self.lock.acquire()
         try:
@@ -708,13 +673,11 @@ class Channel (object):
         transmitted, the application needs to attempt delivery of the remaining
         data.
 
-        @param s: data to send
-        @type s: str
-        @return: number of bytes actually sent
-        @rtype: int
+        :param str s: data to send
+        :return: number of bytes actually sent, as an `int`
 
-        @raise socket.timeout: if no data could be sent before the timeout set
-            by L{settimeout}.
+        :raises socket.timeout: if no data could be sent before the timeout set
+            by `settimeout`.
         """
         size = len(s)
         self.lock.acquire()
@@ -724,7 +687,7 @@ class Channel (object):
                 # eof or similar
                 return 0
             m = Message()
-            m.add_byte(chr(MSG_CHANNEL_DATA))
+            m.add_byte(cMSG_CHANNEL_DATA)
             m.add_int(self.remote_chanid)
             m.add_string(s[:size])
         finally:
@@ -743,15 +706,13 @@ class Channel (object):
         data has been sent: if only some of the data was transmitted, the
         application needs to attempt delivery of the remaining data.
         
-        @param s: data to send.
-        @type s: str
-        @return: number of bytes actually sent.
-        @rtype: int
+        :param str s: data to send.
+        :return: number of bytes actually sent, as an `int`.
         
-        @raise socket.timeout: if no data could be sent before the timeout set
-            by L{settimeout}.
+        :raises socket.timeout:
+            if no data could be sent before the timeout set by `settimeout`.
         
-        @since: 1.1
+        .. versionadded:: 1.1
         """
         size = len(s)
         self.lock.acquire()
@@ -761,7 +722,7 @@ class Channel (object):
                 # eof or similar
                 return 0
             m = Message()
-            m.add_byte(chr(MSG_CHANNEL_EXTENDED_DATA))
+            m.add_byte(cMSG_CHANNEL_EXTENDED_DATA)
             m.add_int(self.remote_chanid)
             m.add_int(1)
             m.add_string(s[:size])
@@ -775,20 +736,20 @@ class Channel (object):
     def sendall(self, s):
         """
         Send data to the channel, without allowing partial results.  Unlike
-        L{send}, this method continues to send data from the given string until
+        `send`, this method continues to send data from the given string until
         either all data has been sent or an error occurs.  Nothing is returned.
 
-        @param s: data to send.
-        @type s: str
+        :param str s: data to send.
 
-        @raise socket.timeout: if sending stalled for longer than the timeout
-            set by L{settimeout}.
-        @raise socket.error: if an error occured before the entire string was
-            sent.
+        :raises socket.timeout:
+            if sending stalled for longer than the timeout set by `settimeout`.
+        :raises socket.error:
+            if an error occured before the entire string was sent.
         
-        @note: If the channel is closed while only part of the data hase been
+        .. note::
+            If the channel is closed while only part of the data hase been
             sent, there is no way to determine how much data (if any) was sent.
-            This is irritating, but identically follows python's API.
+            This is irritating, but identically follows Python's API.
         """
         while s:
             if self.closed:
@@ -801,19 +762,18 @@ class Channel (object):
     def sendall_stderr(self, s):
         """
         Send data to the channel's "stderr" stream, without allowing partial
-        results.  Unlike L{send_stderr}, this method continues to send data
+        results.  Unlike `send_stderr`, this method continues to send data
         from the given string until all data has been sent or an error occurs.
         Nothing is returned.
         
-        @param s: data to send to the client as "stderr" output.
-        @type s: str
+        :param str s: data to send to the client as "stderr" output.
         
-        @raise socket.timeout: if sending stalled for longer than the timeout
-            set by L{settimeout}.
-        @raise socket.error: if an error occured before the entire string was
-            sent.
+        :raises socket.timeout:
+            if sending stalled for longer than the timeout set by `settimeout`.
+        :raises socket.error:
+            if an error occured before the entire string was sent.
             
-        @since: 1.1
+        .. versionadded:: 1.1
         """
         while s:
             if self.closed:
@@ -825,49 +785,46 @@ class Channel (object):
     def makefile(self, *params):
         """
         Return a file-like object associated with this channel.  The optional
-        C{mode} and C{bufsize} arguments are interpreted the same way as by
-        the built-in C{file()} function in python.
+        ``mode`` and ``bufsize`` arguments are interpreted the same way as by
+        the built-in ``file()`` function in Python.
 
-        @return: object which can be used for python file I/O.
-        @rtype: L{ChannelFile}
+        :return: `.ChannelFile` object which can be used for Python file I/O.
         """
         return ChannelFile(*([self] + list(params)))
 
     def makefile_stderr(self, *params):
         """
         Return a file-like object associated with this channel's stderr
-        stream.   Only channels using L{exec_command} or L{invoke_shell}
+        stream.   Only channels using `exec_command` or `invoke_shell`
         without a pty will ever have data on the stderr stream.
         
-        The optional C{mode} and C{bufsize} arguments are interpreted the
-        same way as by the built-in C{file()} function in python.  For a
+        The optional ``mode`` and ``bufsize`` arguments are interpreted the
+        same way as by the built-in ``file()`` function in Python.  For a
         client, it only makes sense to open this file for reading.  For a
         server, it only makes sense to open this file for writing.
         
-        @return: object which can be used for python file I/O.
-        @rtype: L{ChannelFile}
+        :return: `.ChannelFile` object which can be used for Python file I/O.
 
-        @since: 1.1
+        .. versionadded:: 1.1
         """
         return ChannelStderrFile(*([self] + list(params)))
         
     def fileno(self):
         """
         Returns an OS-level file descriptor which can be used for polling, but
-        but I{not} for reading or writing.  This is primaily to allow python's
-        C{select} module to work.
+        but not for reading or writing.  This is primaily to allow Python's
+        ``select`` module to work.
 
-        The first time C{fileno} is called on a channel, a pipe is created to
+        The first time ``fileno`` is called on a channel, a pipe is created to
         simulate real OS-level file descriptor (FD) behavior.  Because of this,
         two OS-level FDs are created, which will use up FDs faster than normal.
         (You won't notice this effect unless you have hundreds of channels
         open at the same time.)
 
-        @return: an OS-level file descriptor
-        @rtype: int
+        :return: an OS-level file descriptor (`int`)
         
-        @warning: This method causes channel reads to be slightly less
-            efficient.
+        .. warning::
+            This method causes channel reads to be slightly less efficient.
         """
         self.lock.acquire()
         try:
@@ -884,14 +841,14 @@ class Channel (object):
 
     def shutdown(self, how):
         """
-        Shut down one or both halves of the connection.  If C{how} is 0,
-        further receives are disallowed.  If C{how} is 1, further sends
-        are disallowed.  If C{how} is 2, further sends and receives are
+        Shut down one or both halves of the connection.  If ``how`` is 0,
+        further receives are disallowed.  If ``how`` is 1, further sends
+        are disallowed.  If ``how`` is 2, further sends and receives are
         disallowed.  This closes the stream in one or both directions.
 
-        @param how: 0 (stop receiving), 1 (stop sending), or 2 (stop
-            receiving and sending).
-        @type how: int
+        :param int how:
+            0 (stop receiving), 1 (stop sending), or 2 (stop receiving and
+              sending).
         """
         if (how == 0) or (how == 2):
             # feign "read" shutdown
@@ -910,10 +867,10 @@ class Channel (object):
         Shutdown the receiving side of this socket, closing the stream in
         the incoming direction.  After this call, future reads on this
         channel will fail instantly.  This is a convenience method, equivalent
-        to C{shutdown(0)}, for people who don't make it a habit to
+        to ``shutdown(0)``, for people who don't make it a habit to
         memorize unix constants from the 1970s.
         
-        @since: 1.2
+        .. versionadded:: 1.2
         """
         self.shutdown(0)
     
@@ -922,17 +879,15 @@ class Channel (object):
         Shutdown the sending side of this socket, closing the stream in
         the outgoing direction.  After this call, future writes on this
         channel will fail instantly.  This is a convenience method, equivalent
-        to C{shutdown(1)}, for people who don't make it a habit to
+        to ``shutdown(1)``, for people who don't make it a habit to
         memorize unix constants from the 1970s.
         
-        @since: 1.2
+        .. versionadded:: 1.2
         """
         self.shutdown(1)
 
-
     ###  calls from Transport
 
-
     def _set_transport(self, transport):
         self.transport = transport
         self.logger = util.get_logger(self.transport.get_log_channel())
@@ -969,16 +924,16 @@ class Channel (object):
                 self.transport._send_user_message(m)
 
     def _feed(self, m):
-        if type(m) is str:
+        if isinstance(m, bytes_types):
             # passed from _feed_extended
             s = m
         else:
-            s = m.get_string()
+            s = m.get_binary()
         self.in_buffer.feed(s)
 
     def _feed_extended(self, m):
         code = m.get_int()
-        s = m.get_string()
+        s = m.get_binary()
         if code != 1:
             self._log(ERROR, 'unknown extended_data type %d; discarding' % code)
             return
@@ -999,7 +954,7 @@ class Channel (object):
             self.lock.release()
 
     def _handle_request(self, m):
-        key = m.get_string()
+        key = m.get_text()
         want_reply = m.get_boolean()
         server = self.transport.server_object
         ok = False
@@ -1035,13 +990,13 @@ class Channel (object):
             else:
                 ok = server.check_channel_env_request(self, name, value)
         elif key == 'exec':
-            cmd = m.get_string()
+            cmd = m.get_text()
             if server is None:
                 ok = False
             else:
                 ok = server.check_channel_exec_request(self, cmd)
         elif key == 'subsystem':
-            name = m.get_string()
+            name = m.get_text()
             if server is None:
                 ok = False
             else:
@@ -1058,8 +1013,8 @@ class Channel (object):
                                                                 pixelheight)
         elif key == 'x11-req':
             single_connection = m.get_boolean()
-            auth_proto = m.get_string()
-            auth_cookie = m.get_string()
+            auth_proto = m.get_text()
+            auth_cookie = m.get_binary()
             screen_number = m.get_int()
             if server is None:
                 ok = False
@@ -1077,9 +1032,9 @@ class Channel (object):
         if want_reply:
             m = Message()
             if ok:
-                m.add_byte(chr(MSG_CHANNEL_SUCCESS))
+                m.add_byte(cMSG_CHANNEL_SUCCESS)
             else:
-                m.add_byte(chr(MSG_CHANNEL_FAILURE))
+                m.add_byte(cMSG_CHANNEL_FAILURE)
             m.add_int(self.remote_chanid)
             self.transport._send_user_message(m)
 
@@ -1107,10 +1062,8 @@ class Channel (object):
             if m is not None:
                 self.transport._send_user_message(m)
 
-
     ###  internals...
 
-
     def _log(self, level, msg, *args):
         self.logger.log(level, "[chan " + self._name + "] " + msg, *args)
 
@@ -1145,7 +1098,7 @@ class Channel (object):
         if self.eof_sent:
             return None
         m = Message()
-        m.add_byte(chr(MSG_CHANNEL_EOF))
+        m.add_byte(cMSG_CHANNEL_EOF)
         m.add_int(self.remote_chanid)
         self.eof_sent = True
         self._log(DEBUG, 'EOF sent (%s)', self._name)
@@ -1157,7 +1110,7 @@ class Channel (object):
             return None, None
         m1 = self._send_eof()
         m2 = Message()
-        m2.add_byte(chr(MSG_CHANNEL_CLOSE))
+        m2.add_byte(cMSG_CHANNEL_CLOSE)
         m2.add_int(self.remote_chanid)
         self._set_closed()
         # can't unlink from the Transport yet -- the remote side may still
@@ -1196,7 +1149,7 @@ class Channel (object):
     def _wait_for_send_window(self, size):
         """
         (You are already holding the lock.)
-        Wait for the send window to open up, and allocate up to C{size} bytes
+        Wait for the send window to open up, and allocate up to ``size`` bytes
         for transmission.  If no space opens up before the timeout, a timeout
         exception is raised.  Returns the number of bytes available to send
         (may be less than requested).
@@ -1215,7 +1168,7 @@ class Channel (object):
                     return 0
                 then = time.time()
                 self.out_buffer_cv.wait(timeout)
-                if timeout != None:
+                if timeout is not None:
                     timeout -= time.time() - then
                     if timeout <= 0.0:
                         raise socket.timeout()
@@ -1234,16 +1187,18 @@ class Channel (object):
 
 class ChannelFile (BufferedFile):
     """
-    A file-like wrapper around L{Channel}.  A ChannelFile is created by calling
-    L{Channel.makefile}.
-
-    @bug: To correctly emulate the file object created from a socket's
-        C{makefile} method, a L{Channel} and its C{ChannelFile} should be able
-        to be closed or garbage-collected independently.  Currently, closing
-        the C{ChannelFile} does nothing but flush the buffer.
+    A file-like wrapper around `.Channel`.  A ChannelFile is created by calling
+    `Channel.makefile`.
+
+    .. warning::
+        To correctly emulate the file object created from a socket's `makefile
+        <python:socket.socket.makefile>` method, a `.Channel` and its
+        `.ChannelFile` should be able to be closed or garbage-collected
+        independently. Currently, closing the `ChannelFile` does nothing but
+        flush the buffer.
     """
 
-    def __init__(self, channel, mode = 'r', bufsize = -1):
+    def __init__(self, channel, mode='r', bufsize=-1):
         self.channel = channel
         BufferedFile.__init__(self)
         self._set_mode(mode, bufsize)
@@ -1251,8 +1206,6 @@ class ChannelFile (BufferedFile):
     def __repr__(self):
         """
         Returns a string representation of this object, for debugging.
-
-        @rtype: str
         """
         return '<paramiko.ChannelFile from ' + repr(self.channel) + '>'
 
@@ -1265,7 +1218,7 @@ class ChannelFile (BufferedFile):
 
 
 class ChannelStderrFile (ChannelFile):
-    def __init__(self, channel, mode = 'r', bufsize = -1):
+    def __init__(self, channel, mode='r', bufsize=-1):
         ChannelFile.__init__(self, channel, mode, bufsize)
 
     def _read(self, size):
diff --git a/paramiko/client.py b/paramiko/client.py
index be89609..c1bf473 100644
--- a/paramiko/client.py
+++ b/paramiko/client.py
@@ -17,7 +17,7 @@
 # 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA.
 
 """
-L{SSHClient}.
+SSH client & key policies
 """
 
 from binascii import hexlify
@@ -27,10 +27,11 @@ import socket
 import warnings
 
 from paramiko.agent import Agent
-from paramiko.common import *
+from paramiko.common import DEBUG
 from paramiko.config import SSH_PORT
 from paramiko.dsskey import DSSKey
 from paramiko.hostkeys import HostKeys
+from paramiko.py3compat import string_types
 from paramiko.resource import ResourceManager
 from paramiko.rsakey import RSAKey
 from paramiko.ssh_exception import SSHException, BadHostKeyException
@@ -38,67 +39,10 @@ from paramiko.transport import Transport
 from paramiko.util import retry_on_signal
 
 
-class MissingHostKeyPolicy (object):
-    """
-    Interface for defining the policy that L{SSHClient} should use when the
-    SSH server's hostname is not in either the system host keys or the
-    application's keys.  Pre-made classes implement policies for automatically
-    adding the key to the application's L{HostKeys} object (L{AutoAddPolicy}),
-    and for automatically rejecting the key (L{RejectPolicy}).
-
-    This function may be used to ask the user to verify the key, for example.
-    """
-
-    def missing_host_key(self, client, hostname, key):
-        """
-        Called when an L{SSHClient} receives a server key for a server that
-        isn't in either the system or local L{HostKeys} object.  To accept
-        the key, simply return.  To reject, raised an exception (which will
-        be passed to the calling application).
-        """
-        pass
-
-
-class AutoAddPolicy (MissingHostKeyPolicy):
-    """
-    Policy for automatically adding the hostname and new host key to the
-    local L{HostKeys} object, and saving it.  This is used by L{SSHClient}.
-    """
-
-    def missing_host_key(self, client, hostname, key):
-        client._host_keys.add(hostname, key.get_name(), key)
-        if client._host_keys_filename is not None:
-            client.save_host_keys(client._host_keys_filename)
-        client._log(DEBUG, 'Adding %s host key for %s: %s' %
-                    (key.get_name(), hostname, hexlify(key.get_fingerprint())))
-
-
-class RejectPolicy (MissingHostKeyPolicy):
-    """
-    Policy for automatically rejecting the unknown hostname & key.  This is
-    used by L{SSHClient}.
-    """
-
-    def missing_host_key(self, client, hostname, key):
-        client._log(DEBUG, 'Rejecting %s host key for %s: %s' %
-                    (key.get_name(), hostname, hexlify(key.get_fingerprint())))
-        raise SSHException('Server %r not found in known_hosts' % hostname)
-
-
-class WarningPolicy (MissingHostKeyPolicy):
-    """
-    Policy for logging a python-style warning for an unknown host key, but
-    accepting it. This is used by L{SSHClient}.
-    """
-    def missing_host_key(self, client, hostname, key):
-        warnings.warn('Unknown %s host key for %s: %s' %
-                      (key.get_name(), hostname, hexlify(key.get_fingerprint())))
-
-
 class SSHClient (object):
     """
     A high-level representation of a session with an SSH server.  This class
-    wraps L{Transport}, L{Channel}, and L{SFTPClient} to take care of most
+    wraps `.Transport`, `.Channel`, and `.SFTPClient` to take care of most
     aspects of authenticating and opening channels.  A typical use case is::
 
         client = SSHClient()
@@ -110,7 +54,7 @@ class SSHClient (object):
     checking.  The default mechanism is to try to use local key files or an
     SSH agent (if one is running).
 
-    @since: 1.6
+    .. versionadded:: 1.6
     """
 
     def __init__(self):
@@ -128,22 +72,21 @@ class SSHClient (object):
     def load_system_host_keys(self, filename=None):
         """
         Load host keys from a system (read-only) file.  Host keys read with
-        this method will not be saved back by L{save_host_keys}.
+        this method will not be saved back by `save_host_keys`.
 
         This method can be called multiple times.  Each new set of host keys
         will be merged with the existing set (new replacing old if there are
         conflicts).
 
-        If C{filename} is left as C{None}, an attempt will be made to read
+        If ``filename`` is left as ``None``, an attempt will be made to read
         keys from the user's local "known hosts" file, as used by OpenSSH,
         and no exception will be raised if the file can't be read.  This is
         probably only useful on posix.
 
-        @param filename: the filename to read, or C{None}
-        @type filename: str
+        :param str filename: the filename to read, or ``None``
 
-        @raise IOError: if a filename was provided and the file could not be
-            read
+        :raises IOError:
+            if a filename was provided and the file could not be read
         """
         if filename is None:
             # try the user's .ssh key file, and mask exceptions
@@ -158,19 +101,18 @@ class SSHClient (object):
     def load_host_keys(self, filename):
         """
         Load host keys from a local host-key file.  Host keys read with this
-        method will be checked I{after} keys loaded via L{load_system_host_keys},
-        but will be saved back by L{save_host_keys} (so they can be modified).
-        The missing host key policy L{AutoAddPolicy} adds keys to this set and
+        method will be checked after keys loaded via `load_system_host_keys`,
+        but will be saved back by `save_host_keys` (so they can be modified).
+        The missing host key policy `.AutoAddPolicy` adds keys to this set and
         saves them, when connecting to a previously-unknown server.
 
         This method can be called multiple times.  Each new set of host keys
         will be merged with the existing set (new replacing old if there are
         conflicts).  When automatically saving, the last hostname is used.
 
-        @param filename: the filename to read
-        @type filename: str
+        :param str filename: the filename to read
 
-        @raise IOError: if the filename could not be read
+        :raises IOError: if the filename could not be read
         """
         self._host_keys_filename = filename
         self._host_keys.load(filename)
@@ -178,13 +120,12 @@ class SSHClient (object):
     def save_host_keys(self, filename):
         """
         Save the host keys back to a file.  Only the host keys loaded with
-        L{load_host_keys} (plus any added directly) will be saved -- not any
-        host keys loaded with L{load_system_host_keys}.
+        `load_host_keys` (plus any added directly) will be saved -- not any
+        host keys loaded with `load_system_host_keys`.
 
-        @param filename: the filename to save to
-        @type filename: str
+        :param str filename: the filename to save to
 
-        @raise IOError: if the file could not be written
+        :raises IOError: if the file could not be written
         """
 
         # update local host keys from file (in case other SSH clients
@@ -192,42 +133,39 @@ class SSHClient (object):
         if self._host_keys_filename is not None:
             self.load_host_keys(self._host_keys_filename)
 
-        f = open(filename, 'w')
-        for hostname, keys in self._host_keys.iteritems():
-            for keytype, key in keys.iteritems():
-                f.write('%s %s %s\n' % (hostname, keytype, key.get_base64()))
-        f.close()
+        with open(filename, 'w') as f:
+            for hostname, keys in self._host_keys.items():
+                for keytype, key in keys.items():
+                    f.write('%s %s %s\n' % (hostname, keytype, key.get_base64()))
 
     def get_host_keys(self):
         """
-        Get the local L{HostKeys} object.  This can be used to examine the
+        Get the local `.HostKeys` object.  This can be used to examine the
         local host keys or change them.
 
-        @return: the local host keys
-        @rtype: L{HostKeys}
+        :return: the local host keys as a `.HostKeys` object.
         """
         return self._host_keys
 
     def set_log_channel(self, name):
         """
-        Set the channel for logging.  The default is C{"paramiko.transport"}
+        Set the channel for logging.  The default is ``"paramiko.transport"``
         but it can be set to anything you want.
 
-        @param name: new channel name for logging
-        @type name: str
+        :param str name: new channel name for logging
         """
         self._log_channel = name
 
     def set_missing_host_key_policy(self, policy):
         """
         Set the policy to use when connecting to a server that doesn't have a
-        host key in either the system or local L{HostKeys} objects.  The
-        default policy is to reject all unknown servers (using L{RejectPolicy}).
-        You may substitute L{AutoAddPolicy} or write your own policy class.
+        host key in either the system or local `.HostKeys` objects.  The
+        default policy is to reject all unknown servers (using `.RejectPolicy`).
+        You may substitute `.AutoAddPolicy` or write your own policy class.
 
-        @param policy: the policy to use when receiving a host key from a
+        :param .MissingHostKeyPolicy policy:
+            the policy to use when receiving a host key from a
             previously-unknown server
-        @type policy: L{MissingHostKeyPolicy}
         """
         self._policy = policy
 
@@ -236,56 +174,49 @@ class SSHClient (object):
                 compress=False, sock=None):
         """
         Connect to an SSH server and authenticate to it.  The server's host key
-        is checked against the system host keys (see L{load_system_host_keys})
-        and any local host keys (L{load_host_keys}).  If the server's hostname
+        is checked against the system host keys (see `load_system_host_keys`)
+        and any local host keys (`load_host_keys`).  If the server's hostname
         is not found in either set of host keys, the missing host key policy
-        is used (see L{set_missing_host_key_policy}).  The default policy is
-        to reject the key and raise an L{SSHException}.
+        is used (see `set_missing_host_key_policy`).  The default policy is
+        to reject the key and raise an `.SSHException`.
 
         Authentication is attempted in the following order of priority:
 
-            - The C{pkey} or C{key_filename} passed in (if any)
+            - The ``pkey`` or ``key_filename`` passed in (if any)
             - Any key we can find through an SSH agent
-            - Any "id_rsa" or "id_dsa" key discoverable in C{~/.ssh/}
+            - Any "id_rsa" or "id_dsa" key discoverable in ``~/.ssh/``
             - Plain username/password auth, if a password was given
 
         If a private key requires a password to unlock it, and a password is
         passed in, that password will be used to attempt to unlock the key.
 
-        @param hostname: the server to connect to
-        @type hostname: str
-        @param port: the server port to connect to
-        @type port: int
-        @param username: the username to authenticate as (defaults to the
-            current local username)
-        @type username: str
-        @param password: a password to use for authentication or for unlocking
-            a private key
-        @type password: str
-        @param pkey: an optional private key to use for authentication
-        @type pkey: L{PKey}
-        @param key_filename: the filename, or list of filenames, of optional
-            private key(s) to try for authentication
-        @type key_filename: str or list(str)
-        @param timeout: an optional timeout (in seconds) for the TCP connect
-        @type timeout: float
-        @param allow_agent: set to False to disable connecting to the SSH agent
-        @type allow_agent: bool
-        @param look_for_keys: set to False to disable searching for discoverable
-            private key files in C{~/.ssh/}
-        @type look_for_keys: bool
-        @param compress: set to True to turn on compression
-        @type compress: bool
-        @param sock: an open socket or socket-like object (such as a
-            L{Channel}) to use for communication to the target host
-        @type sock: socket
-
-        @raise BadHostKeyException: if the server's host key could not be
+        :param str hostname: the server to connect to
+        :param int port: the server port to connect to
+        :param str username:
+            the username to authenticate as (defaults to the current local
+            username)
+        :param str password:
+            a password to use for authentication or for unlocking a private key
+        :param .PKey pkey: an optional private key to use for authentication
+        :param str key_filename:
+            the filename, or list of filenames, of optional private key(s) to
+            try for authentication
+        :param float timeout: an optional timeout (in seconds) for the TCP connect
+        :param bool allow_agent: set to False to disable connecting to the SSH agent
+        :param bool look_for_keys:
+            set to False to disable searching for discoverable private key
+            files in ``~/.ssh/``
+        :param bool compress: set to True to turn on compression
+        :param socket sock:
+            an open socket or socket-like object (such as a `.Channel`) to use
+            for communication to the target host
+
+        :raises BadHostKeyException: if the server's host key could not be
             verified
-        @raise AuthenticationException: if authentication failed
-        @raise SSHException: if there was any other error connecting or
+        :raises AuthenticationException: if authentication failed
+        :raises SSHException: if there was any other error connecting or
             establishing an SSH session
-        @raise socket.error: if a socket error occurred while connecting
+        :raises socket.error: if a socket error occurred while connecting
         """
         if not sock:
             for (family, socktype, proto, canonname, sockaddr) in socket.getaddrinfo(hostname, port, socket.AF_UNSPEC, socket.SOCK_STREAM):
@@ -335,74 +266,70 @@ class SSHClient (object):
 
         if key_filename is None:
             key_filenames = []
-        elif isinstance(key_filename, (str, unicode)):
-            key_filenames = [ key_filename ]
+        elif isinstance(key_filename, string_types):
+            key_filenames = [key_filename]
         else:
             key_filenames = key_filename
         self._auth(username, password, pkey, key_filenames, allow_agent, look_for_keys)
 
     def close(self):
         """
-        Close this SSHClient and its underlying L{Transport}.
+        Close this SSHClient and its underlying `.Transport`.
         """
         if self._transport is None:
             return
         self._transport.close()
         self._transport = None
 
-        if self._agent != None:
+        if self._agent is not None:
             self._agent.close()
             self._agent = None
 
     def exec_command(self, command, bufsize=-1, timeout=None, get_pty=False):
         """
-        Execute a command on the SSH server.  A new L{Channel} is opened and
+        Execute a command on the SSH server.  A new `.Channel` is opened and
         the requested command is executed.  The command's input and output
-        streams are returned as python C{file}-like objects representing
+        streams are returned as Python ``file``-like objects representing
         stdin, stdout, and stderr.
 
-        @param command: the command to execute
-        @type command: str
-        @param bufsize: interpreted the same way as by the built-in C{file()} function in python
-        @type bufsize: int
-        @param timeout: set command's channel timeout. See L{Channel.settimeout}.settimeout
-        @type timeout: int
-        @return: the stdin, stdout, and stderr of the executing command
-        @rtype: tuple(L{ChannelFile}, L{ChannelFile}, L{ChannelFile})
-
-        @raise SSHException: if the server fails to execute the command
+        :param str command: the command to execute
+        :param int bufsize:
+            interpreted the same way as by the built-in ``file()`` function in
+            Python
+        :param int timeout:
+            set command's channel timeout. See `Channel.settimeout`.settimeout
+        :return:
+            the stdin, stdout, and stderr of the executing command, as a
+            3-tuple
+
+        :raises SSHException: if the server fails to execute the command
         """
         chan = self._transport.open_session()
-        if(get_pty):
+        if get_pty:
             chan.get_pty()
         chan.settimeout(timeout)
         chan.exec_command(command)
         stdin = chan.makefile('wb', bufsize)
-        stdout = chan.makefile('rb', bufsize)
-        stderr = chan.makefile_stderr('rb', bufsize)
+        stdout = chan.makefile('r', bufsize)
+        stderr = chan.makefile_stderr('r', bufsize)
         return stdin, stdout, stderr
 
     def invoke_shell(self, term='vt100', width=80, height=24, width_pixels=0,
-                height_pixels=0):
+                     height_pixels=0):
         """
-        Start an interactive shell session on the SSH server.  A new L{Channel}
+        Start an interactive shell session on the SSH server.  A new `.Channel`
         is opened and connected to a pseudo-terminal using the requested
         terminal type and size.
 
-        @param term: the terminal type to emulate (for example, C{"vt100"})
-        @type term: str
-        @param width: the width (in characters) of the terminal window
-        @type width: int
-        @param height: the height (in characters) of the terminal window
-        @type height: int
-        @param width_pixels: the width (in pixels) of the terminal window
-        @type width_pixels: int
-        @param height_pixels: the height (in pixels) of the terminal window
-        @type height_pixels: int
-        @return: a new channel connected to the remote shell
-        @rtype: L{Channel}
-
-        @raise SSHException: if the server fails to invoke a shell
+        :param str term:
+            the terminal type to emulate (for example, ``"vt100"``)
+        :param int width: the width (in characters) of the terminal window
+        :param int height: the height (in characters) of the terminal window
+        :param int width_pixels: the width (in pixels) of the terminal window
+        :param int height_pixels: the height (in pixels) of the terminal window
+        :return: a new `.Channel` connected to the remote shell
+
+        :raises SSHException: if the server fails to invoke a shell
         """
         chan = self._transport.open_session()
         chan.get_pty(term, width, height, width_pixels, height_pixels)
@@ -413,19 +340,17 @@ class SSHClient (object):
         """
         Open an SFTP session on the SSH server.
 
-        @return: a new SFTP session object
-        @rtype: L{SFTPClient}
+        :return: a new `.SFTPClient` session object
         """
         return self._transport.open_sftp_client()
 
     def get_transport(self):
         """
-        Return the underlying L{Transport} object for this SSH connection.
+        Return the underlying `.Transport` object for this SSH connection.
         This can be used to perform lower-level tasks, like opening specific
         kinds of channels.
 
-        @return: the Transport for this connection
-        @rtype: L{Transport}
+        :return: the `.Transport` for this connection
         """
         return self._transport
 
@@ -452,7 +377,7 @@ class SSHClient (object):
                 two_factor = (allowed_types == ['password'])
                 if not two_factor:
                     return
-            except SSHException, e:
+            except SSHException as e:
                 saved_exception = e
 
         if not two_factor:
@@ -466,11 +391,11 @@ class SSHClient (object):
                         if not two_factor:
                             return
                         break
-                    except SSHException, e:
+                    except SSHException as e:
                         saved_exception = e
 
         if not two_factor and allow_agent:
-            if self._agent == None:
+            if self._agent is None:
                 self._agent = Agent()
 
             for key in self._agent.get_keys():
@@ -482,7 +407,7 @@ class SSHClient (object):
                     if not two_factor:
                         return
                     break
-                except SSHException, e:
+                except SSHException as e:
                     saved_exception = e
 
         if not two_factor:
@@ -514,16 +439,14 @@ class SSHClient (object):
                     if not two_factor:
                         return
                     break
-                except SSHException, e:
-                    saved_exception = e
-                except IOError, e:
+                except (SSHException, IOError) as e:
                     saved_exception = e
 
         if password is not None:
             try:
                 self._transport.auth_password(username, password)
                 return
-            except SSHException, e:
+            except SSHException as e:
                 saved_exception = e
         elif two_factor:
             raise SSHException('Two-factor authentication requires a password')
@@ -536,3 +459,59 @@ class SSHClient (object):
     def _log(self, level, msg):
         self._transport._log(level, msg)
 
+
+class MissingHostKeyPolicy (object):
+    """
+    Interface for defining the policy that `.SSHClient` should use when the
+    SSH server's hostname is not in either the system host keys or the
+    application's keys.  Pre-made classes implement policies for automatically
+    adding the key to the application's `.HostKeys` object (`.AutoAddPolicy`),
+    and for automatically rejecting the key (`.RejectPolicy`).
+
+    This function may be used to ask the user to verify the key, for example.
+    """
+
+    def missing_host_key(self, client, hostname, key):
+        """
+        Called when an `.SSHClient` receives a server key for a server that
+        isn't in either the system or local `.HostKeys` object.  To accept
+        the key, simply return.  To reject, raised an exception (which will
+        be passed to the calling application).
+        """
+        pass
+
+
+class AutoAddPolicy (MissingHostKeyPolicy):
+    """
+    Policy for automatically adding the hostname and new host key to the
+    local `.HostKeys` object, and saving it.  This is used by `.SSHClient`.
+    """
+
+    def missing_host_key(self, client, hostname, key):
+        client._host_keys.add(hostname, key.get_name(), key)
+        if client._host_keys_filename is not None:
+            client.save_host_keys(client._host_keys_filename)
+        client._log(DEBUG, 'Adding %s host key for %s: %s' %
+                    (key.get_name(), hostname, hexlify(key.get_fingerprint())))
+
+
+class RejectPolicy (MissingHostKeyPolicy):
+    """
+    Policy for automatically rejecting the unknown hostname & key.  This is
+    used by `.SSHClient`.
+    """
+
+    def missing_host_key(self, client, hostname, key):
+        client._log(DEBUG, 'Rejecting %s host key for %s: %s' %
+                    (key.get_name(), hostname, hexlify(key.get_fingerprint())))
+        raise SSHException('Server %r not found in known_hosts' % hostname)
+
+
+class WarningPolicy (MissingHostKeyPolicy):
+    """
+    Policy for logging a Python-style warning for an unknown host key, but
+    accepting it. This is used by `.SSHClient`.
+    """
+    def missing_host_key(self, client, hostname, key):
+        warnings.warn('Unknown %s host key for %s: %s' %
+                      (key.get_name(), hostname, hexlify(key.get_fingerprint())))
diff --git a/paramiko/common.py b/paramiko/common.py
index 3d7ca58..1829892 100644
--- a/paramiko/common.py
+++ b/paramiko/common.py
@@ -19,12 +19,14 @@
 """
 Common constants and global variables.
 """
+import logging
+from paramiko.py3compat import byte_chr, PY2, bytes_types, string_types, b, long
 
 MSG_DISCONNECT, MSG_IGNORE, MSG_UNIMPLEMENTED, MSG_DEBUG, MSG_SERVICE_REQUEST, \
     MSG_SERVICE_ACCEPT = range(1, 7)
 MSG_KEXINIT, MSG_NEWKEYS = range(20, 22)
 MSG_USERAUTH_REQUEST, MSG_USERAUTH_FAILURE, MSG_USERAUTH_SUCCESS, \
-        MSG_USERAUTH_BANNER = range(50, 54)
+    MSG_USERAUTH_BANNER = range(50, 54)
 MSG_USERAUTH_PK_OK = 60
 MSG_USERAUTH_INFO_REQUEST, MSG_USERAUTH_INFO_RESPONSE = range(60, 62)
 MSG_GLOBAL_REQUEST, MSG_REQUEST_SUCCESS, MSG_REQUEST_FAILURE = range(80, 83)
@@ -33,6 +35,35 @@ MSG_CHANNEL_OPEN, MSG_CHANNEL_OPEN_SUCCESS, MSG_CHANNEL_OPEN_FAILURE, \
     MSG_CHANNEL_EOF, MSG_CHANNEL_CLOSE, MSG_CHANNEL_REQUEST, \
     MSG_CHANNEL_SUCCESS, MSG_CHANNEL_FAILURE = range(90, 101)
 
+cMSG_DISCONNECT = byte_chr(MSG_DISCONNECT)
+cMSG_IGNORE = byte_chr(MSG_IGNORE)
+cMSG_UNIMPLEMENTED = byte_chr(MSG_UNIMPLEMENTED)
+cMSG_DEBUG = byte_chr(MSG_DEBUG)
+cMSG_SERVICE_REQUEST = byte_chr(MSG_SERVICE_REQUEST)
+cMSG_SERVICE_ACCEPT = byte_chr(MSG_SERVICE_ACCEPT)
+cMSG_KEXINIT = byte_chr(MSG_KEXINIT)
+cMSG_NEWKEYS = byte_chr(MSG_NEWKEYS)
+cMSG_USERAUTH_REQUEST = byte_chr(MSG_USERAUTH_REQUEST)
+cMSG_USERAUTH_FAILURE = byte_chr(MSG_USERAUTH_FAILURE)
+cMSG_USERAUTH_SUCCESS = byte_chr(MSG_USERAUTH_SUCCESS)
+cMSG_USERAUTH_BANNER = byte_chr(MSG_USERAUTH_BANNER)
+cMSG_USERAUTH_PK_OK = byte_chr(MSG_USERAUTH_PK_OK)
+cMSG_USERAUTH_INFO_REQUEST = byte_chr(MSG_USERAUTH_INFO_REQUEST)
+cMSG_USERAUTH_INFO_RESPONSE = byte_chr(MSG_USERAUTH_INFO_RESPONSE)
+cMSG_GLOBAL_REQUEST = byte_chr(MSG_GLOBAL_REQUEST)
+cMSG_REQUEST_SUCCESS = byte_chr(MSG_REQUEST_SUCCESS)
+cMSG_REQUEST_FAILURE = byte_chr(MSG_REQUEST_FAILURE)
+cMSG_CHANNEL_OPEN = byte_chr(MSG_CHANNEL_OPEN)
+cMSG_CHANNEL_OPEN_SUCCESS = byte_chr(MSG_CHANNEL_OPEN_SUCCESS)
+cMSG_CHANNEL_OPEN_FAILURE = byte_chr(MSG_CHANNEL_OPEN_FAILURE)
+cMSG_CHANNEL_WINDOW_ADJUST = byte_chr(MSG_CHANNEL_WINDOW_ADJUST)
+cMSG_CHANNEL_DATA = byte_chr(MSG_CHANNEL_DATA)
+cMSG_CHANNEL_EXTENDED_DATA = byte_chr(MSG_CHANNEL_EXTENDED_DATA)
+cMSG_CHANNEL_EOF = byte_chr(MSG_CHANNEL_EOF)
+cMSG_CHANNEL_CLOSE = byte_chr(MSG_CHANNEL_CLOSE)
+cMSG_CHANNEL_REQUEST = byte_chr(MSG_CHANNEL_REQUEST)
+cMSG_CHANNEL_SUCCESS = byte_chr(MSG_CHANNEL_SUCCESS)
+cMSG_CHANNEL_FAILURE = byte_chr(MSG_CHANNEL_FAILURE)
 
 # for debugging:
 MSG_NAMES = {
@@ -69,7 +100,7 @@ MSG_NAMES = {
     MSG_CHANNEL_REQUEST: 'channel-request',
     MSG_CHANNEL_SUCCESS: 'channel-success',
     MSG_CHANNEL_FAILURE: 'channel-failure'
-    }
+}
 
 
 # authentication request return codes:
@@ -95,29 +126,42 @@ CONNECTION_FAILED_CODE = {
 DISCONNECT_SERVICE_NOT_AVAILABLE, DISCONNECT_AUTH_CANCELLED_BY_USER, \
     DISCONNECT_NO_MORE_AUTH_METHODS_AVAILABLE = 7, 13, 14
 
-from Crypto import Random
-
-# keep a crypto-strong PRNG nearby
-rng = Random.new()
-
-import sys
-if sys.version_info < (2, 3):
-    try:
-        import logging
-    except:
-        import logging22 as logging
-    import select
-    PY22 = True
-
-    import socket
-    if not hasattr(socket, 'timeout'):
-        class timeout(socket.error): pass
-        socket.timeout = timeout
-        del timeout
+zero_byte = byte_chr(0)
+one_byte = byte_chr(1)
+four_byte = byte_chr(4)
+max_byte = byte_chr(0xff)
+cr_byte = byte_chr(13)
+linefeed_byte = byte_chr(10)
+crlf = cr_byte + linefeed_byte
+
+if PY2:
+    cr_byte_value = cr_byte
+    linefeed_byte_value = linefeed_byte
 else:
-    import logging
-    PY22 = False
-
+    cr_byte_value = 13
+    linefeed_byte_value = 10
+
+
+def asbytes(s):
+    if not isinstance(s, bytes_types):
+        if isinstance(s, string_types):
+            s = b(s)
+        else:
+            try:
+                s = s.asbytes()
+            except Exception:
+                raise Exception('Unknown type')
+    return s
+
+xffffffff = long(0xffffffff)
+x80000000 = long(0x80000000)
+o666 = 438
+o660 = 432
+o644 = 420
+o600 = 384
+o777 = 511
+o700 = 448
+o70 = 56
 
 DEBUG = logging.DEBUG
 INFO = logging.INFO
diff --git a/paramiko/config.py b/paramiko/config.py
index 1705de7..77fa13d 100644
--- a/paramiko/config.py
+++ b/paramiko/config.py
@@ -18,7 +18,7 @@
 # 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA.
 
 """
-L{SSHConfig}.
+Configuration file (aka ``ssh_config``) support.
 """
 
 import fnmatch
@@ -30,69 +30,15 @@ SSH_PORT = 22
 proxy_re = re.compile(r"^(proxycommand)\s*=*\s*(.*)", re.I)
 
 
-class LazyFqdn(object):
-    """
-    Returns the host's fqdn on request as string.
-    """
-
-    def __init__(self, config, host=None):
-        self.fqdn = None
-        self.config = config
-        self.host = host
-
-    def __str__(self):
-        if self.fqdn is None:
-            #
-            # If the SSH config contains AddressFamily, use that when
-            # determining  the local host's FQDN. Using socket.getfqdn() from
-            # the standard library is the most general solution, but can
-            # result in noticeable delays on some platforms when IPv6 is
-            # misconfigured or not available, as it calls getaddrinfo with no
-            # address family specified, so both IPv4 and IPv6 are checked.
-            #
-
-            # Handle specific option
-            fqdn = None
-            address_family = self.config.get('addressfamily', 'any').lower()
-            if address_family != 'any':
-                try:
-                    family = socket.AF_INET if address_family == 'inet' \
-                        else socket.AF_INET6
-                    results = socket.getaddrinfo(
-                        self.host,
-                        None,
-                        family,
-                        socket.SOCK_DGRAM,
-                        socket.IPPROTO_IP,
-                        socket.AI_CANONNAME
-                    )
-                    for res in results:
-                        af, socktype, proto, canonname, sa = res
-                        if canonname and '.' in canonname:
-                            fqdn = canonname
-                            break
-                # giaerror -> socket.getaddrinfo() can't resolve self.host
-                # (which is from socket.gethostname()). Fall back to the
-                # getfqdn() call below.
-                except socket.gaierror:
-                    pass
-            # Handle 'any' / unspecified
-            if fqdn is None:
-                fqdn = socket.getfqdn()
-            # Cache
-            self.fqdn = fqdn
-        return self.fqdn
-
-
 class SSHConfig (object):
     """
     Representation of config information as stored in the format used by
-    OpenSSH. Queries can be made via L{lookup}. The format is described in
-    OpenSSH's C{ssh_config} man page. This class is provided primarily as a
+    OpenSSH. Queries can be made via `lookup`. The format is described in
+    OpenSSH's ``ssh_config`` man page. This class is provided primarily as a
     convenience to posix users (since the OpenSSH format is a de-facto
     standard on posix) but should work fine on Windows too.
 
-    @since: 1.6
+    .. versionadded:: 1.6
     """
 
     def __init__(self):
@@ -105,8 +51,7 @@ class SSHConfig (object):
         """
         Read an OpenSSH config from the given file object.
 
-        @param file_obj: a file-like object to read the config file from
-        @type file_obj: file
+        :param file file_obj: a file-like object to read the config file from
         """
         host = {"host": ['*'], "config": {}}
         for line in file_obj:
@@ -152,28 +97,26 @@ class SSHConfig (object):
         """
         Return a dict of config options for a given hostname.
 
-        The host-matching rules of OpenSSH's C{ssh_config} man page are used,
+        The host-matching rules of OpenSSH's ``ssh_config`` man page are used,
         which means that all configuration options from matching host
         specifications are merged, with more specific hostmasks taking
-        precedence. In other words, if C{"Port"} is set under C{"Host *"}
-        and also C{"Host *.example.com"}, and the lookup is for
-        C{"ssh.example.com"}, then the port entry for C{"Host *.example.com"}
+        precedence. In other words, if ``"Port"`` is set under ``"Host *"``
+        and also ``"Host *.example.com"``, and the lookup is for
+        ``"ssh.example.com"``, then the port entry for ``"Host *.example.com"``
         will win out.
 
         The keys in the returned dict are all normalized to lowercase (look for
-        C{"port"}, not C{"Port"}. The values are processed according to the
-        rules for substitution variable expansion in C{ssh_config}.
+        ``"port"``, not ``"Port"``. The values are processed according to the
+        rules for substitution variable expansion in ``ssh_config``.
 
-        @param hostname: the hostname to lookup
-        @type hostname: str
+        :param str hostname: the hostname to lookup
         """
-
         matches = [config for config in self._config if
                    self._allowed(hostname, config['host'])]
 
         ret = {}
         for match in matches:
-            for key, value in match['config'].iteritems():
+            for key, value in match['config'].items():
                 if key not in ret:
                     # Create a copy of the original value,
                     # else it will reference the original list
@@ -199,13 +142,11 @@ class SSHConfig (object):
         Return a dict of config options with expanded substitutions
         for a given hostname.
 
-        Please refer to man C{ssh_config} for the parameters that
+        Please refer to man ``ssh_config`` for the parameters that
         are replaced.
 
-        @param config: the config for the hostname
-        @type hostname: dict
-        @param hostname: the hostname that the config belongs to
-        @type hostname: str
+        :param dict config: the config for the hostname
+        :param str hostname: the hostname that the config belongs to
         """
 
         if 'hostname' in config:
@@ -264,3 +205,57 @@ class SSHConfig (object):
                     else:
                         config[k] = config[k].replace(find, str(replace))
         return config
+
+
+class LazyFqdn(object):
+    """
+    Returns the host's fqdn on request as string.
+    """
+
+    def __init__(self, config, host=None):
+        self.fqdn = None
+        self.config = config
+        self.host = host
+
+    def __str__(self):
+        if self.fqdn is None:
+            #
+            # If the SSH config contains AddressFamily, use that when
+            # determining  the local host's FQDN. Using socket.getfqdn() from
+            # the standard library is the most general solution, but can
+            # result in noticeable delays on some platforms when IPv6 is
+            # misconfigured or not available, as it calls getaddrinfo with no
+            # address family specified, so both IPv4 and IPv6 are checked.
+            #
+
+            # Handle specific option
+            fqdn = None
+            address_family = self.config.get('addressfamily', 'any').lower()
+            if address_family != 'any':
+                try:
+                    family = socket.AF_INET if address_family == 'inet' \
+                        else socket.AF_INET6
+                    results = socket.getaddrinfo(
+                        self.host,
+                        None,
+                        family,
+                        socket.SOCK_DGRAM,
+                        socket.IPPROTO_IP,
+                        socket.AI_CANONNAME
+                    )
+                    for res in results:
+                        af, socktype, proto, canonname, sa = res
+                        if canonname and '.' in canonname:
+                            fqdn = canonname
+                            break
+                # giaerror -> socket.getaddrinfo() can't resolve self.host
+                # (which is from socket.gethostname()). Fall back to the
+                # getfqdn() call below.
+                except socket.gaierror:
+                    pass
+            # Handle 'any' / unspecified
+            if fqdn is None:
+                fqdn = socket.getfqdn()
+            # Cache
+            self.fqdn = fqdn
+        return self.fqdn
diff --git a/paramiko/dsskey.py b/paramiko/dsskey.py
index f6ecb2a..1901596 100644
--- a/paramiko/dsskey.py
+++ b/paramiko/dsskey.py
@@ -17,14 +17,17 @@
 # 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA.
 
 """
-L{DSSKey}
+DSS keys.
 """
 
+import os
+from hashlib import sha1
+
 from Crypto.PublicKey import DSA
-from Crypto.Hash import SHA
 
-from paramiko.common import *
 from paramiko import util
+from paramiko.common import zero_byte
+from paramiko.py3compat import long
 from paramiko.ssh_exception import SSHException
 from paramiko.message import Message
 from paramiko.ber import BER, BERException
@@ -56,7 +59,7 @@ class DSSKey (PKey):
         else:
             if msg is None:
                 raise SSHException('Key object may not be empty')
-            if msg.get_string() != 'ssh-dss':
+            if msg.get_text() != 'ssh-dss':
                 raise SSHException('Invalid key')
             self.p = msg.get_mpint()
             self.q = msg.get_mpint()
@@ -64,14 +67,17 @@ class DSSKey (PKey):
             self.y = msg.get_mpint()
         self.size = util.bit_length(self.p)
 
-    def __str__(self):
+    def asbytes(self):
         m = Message()
         m.add_string('ssh-dss')
         m.add_mpint(self.p)
         m.add_mpint(self.q)
         m.add_mpint(self.g)
         m.add_mpint(self.y)
-        return str(m)
+        return m.asbytes()
+
+    def __str__(self):
+        return self.asbytes()
 
     def __hash__(self):
         h = hash(self.get_name())
@@ -87,17 +93,17 @@ class DSSKey (PKey):
 
     def get_bits(self):
         return self.size
-        
+
     def can_sign(self):
         return self.x is not None
 
-    def sign_ssh_data(self, rng, data):
-        digest = SHA.new(data).digest()
+    def sign_ssh_data(self, data):
+        digest = sha1(data).digest()
         dss = DSA.construct((long(self.y), long(self.g), long(self.p), long(self.q), long(self.x)))
         # generate a suitable k
         qsize = len(util.deflate_long(self.q, 0))
         while True:
-            k = util.inflate_long(rng.read(qsize), 1)
+            k = util.inflate_long(os.urandom(qsize), 1)
             if (k > 2) and (k < self.q):
                 break
         r, s = dss.sign(util.inflate_long(digest, 1), k)
@@ -107,26 +113,26 @@ class DSSKey (PKey):
         rstr = util.deflate_long(r, 0)
         sstr = util.deflate_long(s, 0)
         if len(rstr) < 20:
-            rstr = '\x00' * (20 - len(rstr)) + rstr
+            rstr = zero_byte * (20 - len(rstr)) + rstr
         if len(sstr) < 20:
-            sstr = '\x00' * (20 - len(sstr)) + sstr
+            sstr = zero_byte * (20 - len(sstr)) + sstr
         m.add_string(rstr + sstr)
         return m
 
     def verify_ssh_sig(self, data, msg):
-        if len(str(msg)) == 40:
+        if len(msg.asbytes()) == 40:
             # spies.com bug: signature has no header
-            sig = str(msg)
+            sig = msg.asbytes()
         else:
-            kind = msg.get_string()
+            kind = msg.get_text()
             if kind != 'ssh-dss':
                 return 0
-            sig = msg.get_string()
+            sig = msg.get_binary()
 
         # pull out (r, s) which are NOT encoded as mpints
         sigR = util.inflate_long(sig[:20], 1)
         sigS = util.inflate_long(sig[20:], 1)
-        sigM = util.inflate_long(SHA.new(data).digest(), 1)
+        sigM = util.inflate_long(sha1(data).digest(), 1)
 
         dss = DSA.construct((long(self.y), long(self.g), long(self.p), long(self.q)))
         return dss.verify(sigM, (sigR, sigS))
@@ -134,13 +140,13 @@ class DSSKey (PKey):
     def _encode_key(self):
         if self.x is None:
             raise SSHException('Not enough key information')
-        keylist = [ 0, self.p, self.q, self.g, self.y, self.x ]
+        keylist = [0, self.p, self.q, self.g, self.y, self.x]
         try:
             b = BER()
             b.encode(keylist)
         except BERException:
             raise SSHException('Unable to create ber encoding of key')
-        return str(b)
+        return b.asbytes()
 
     def write_private_key_file(self, filename, password=None):
         self._write_private_key_file('DSA', filename, self._encode_key(), password)
@@ -153,39 +159,35 @@ class DSSKey (PKey):
         Generate a new private DSS key.  This factory function can be used to
         generate a new host key or authentication key.
 
-        @param bits: number of bits the generated key should be.
-        @type bits: int
-        @param progress_func: an optional function to call at key points in
-            key generation (used by C{pyCrypto.PublicKey}).
-        @type progress_func: function
-        @return: new private key
-        @rtype: L{DSSKey}
+        :param int bits: number of bits the generated key should be.
+        :param function progress_func:
+            an optional function to call at key points in key generation (used
+            by ``pyCrypto.PublicKey``).
+        :return: new `.DSSKey` private key
         """
-        dsa = DSA.generate(bits, rng.read, progress_func)
+        dsa = DSA.generate(bits, os.urandom, progress_func)
         key = DSSKey(vals=(dsa.p, dsa.q, dsa.g, dsa.y))
         key.x = dsa.x
         return key
     generate = staticmethod(generate)
 
-
     ###  internals...
 
-
     def _from_private_key_file(self, filename, password):
         data = self._read_private_key_file('DSA', filename, password)
         self._decode_key(data)
-    
+
     def _from_private_key(self, file_obj, password):
         data = self._read_private_key('DSA', file_obj, password)
         self._decode_key(data)
-    
+
     def _decode_key(self, data):
         # private key file contains:
         # DSAPrivateKey = { version = 0, p, q, g, y, x }
         try:
             keylist = BER(data).decode()
-        except BERException, x:
-            raise SSHException('Unable to parse key file: ' + str(x))
+        except BERException as e:
+            raise SSHException('Unable to parse key file: ' + str(e))
         if (type(keylist) is not list) or (len(keylist) < 6) or (keylist[0] != 0):
             raise SSHException('not a valid DSA private key file (bad ber encoding)')
         self.p = keylist[1]
diff --git a/paramiko/ecdsakey.py b/paramiko/ecdsakey.py
index ac840ab..6736315 100644
--- a/paramiko/ecdsakey.py
+++ b/paramiko/ecdsakey.py
@@ -21,16 +21,15 @@ L{ECDSAKey}
 """
 
 import binascii
+from hashlib import sha256
+
 from ecdsa import SigningKey, VerifyingKey, der, curves
-from ecdsa.util import number_to_string, sigencode_string, sigencode_strings, sigdecode_strings
-from Crypto.Hash import SHA256, MD5
-from Crypto.Cipher import DES3
+from ecdsa.test_pyecdsa import ECDSA
 
-from paramiko.common import *
-from paramiko import util
+from paramiko.common import four_byte, one_byte
 from paramiko.message import Message
-from paramiko.ber import BER, BERException
 from paramiko.pkey import PKey
+from paramiko.py3compat import byte_chr, u
 from paramiko.ssh_exception import SSHException
 
 
@@ -56,30 +55,33 @@ class ECDSAKey (PKey):
         else:
             if msg is None:
                 raise SSHException('Key object may not be empty')
-            if msg.get_string() != 'ecdsa-sha2-nistp256':
+            if msg.get_text() != 'ecdsa-sha2-nistp256':
                 raise SSHException('Invalid key')
-            curvename = msg.get_string()
+            curvename = msg.get_text()
             if curvename != 'nistp256':
                 raise SSHException("Can't handle curve of type %s" % curvename)
 
-            pointinfo = msg.get_string()
-            if pointinfo[0] != "\x04":
-                raise SSHException('Point compression is being used: %s'%
+            pointinfo = msg.get_binary()
+            if pointinfo[0:1] != four_byte:
+                raise SSHException('Point compression is being used: %s' %
                                    binascii.hexlify(pointinfo))
             self.verifying_key = VerifyingKey.from_string(pointinfo[1:],
-                curve=curves.NIST256p)
+                                                          curve=curves.NIST256p)
         self.size = 256
 
-    def __str__(self):
+    def asbytes(self):
         key = self.verifying_key
         m = Message()
         m.add_string('ecdsa-sha2-nistp256')
         m.add_string('nistp256')
 
-        point_str = "\x04" + key.to_string()
+        point_str = four_byte + key.to_string()
 
         m.add_string(point_str)
-        return str(m)
+        return m.asbytes()
+
+    def __str__(self):
+        return self.asbytes()
 
     def __hash__(self):
         h = hash(self.get_name())
@@ -96,23 +98,22 @@ class ECDSAKey (PKey):
     def can_sign(self):
         return self.signing_key is not None
 
-    def sign_ssh_data(self, rpool, data):
-        digest = SHA256.new(data).digest()
-        sig = self.signing_key.sign_digest(digest, entropy=rpool.read,
-                                           sigencode=self._sigencode)
+    def sign_ssh_data(self, data):
+        sig = self.signing_key.sign_deterministic(
+            data, sigencode=self._sigencode, hashfunc=sha256)
         m = Message()
         m.add_string('ecdsa-sha2-nistp256')
         m.add_string(sig)
         return m
 
     def verify_ssh_sig(self, data, msg):
-        if msg.get_string() != 'ecdsa-sha2-nistp256':
+        if msg.get_text() != 'ecdsa-sha2-nistp256':
             return False
-        sig = msg.get_string()
+        sig = msg.get_binary()
 
         # verify the signature by SHA'ing the data and encrypting it
         # using the public key.
-        hash_obj = SHA256.new(data).digest()
+        hash_obj = sha256(data).digest()
         return self.verifying_key.verify_digest(sig, hash_obj,
                                                 sigdecode=self._sigdecode)
 
@@ -142,10 +143,8 @@ class ECDSAKey (PKey):
         return key
     generate = staticmethod(generate)
 
-
     ###  internals...
 
-
     def _from_private_key_file(self, filename, password):
         data = self._read_private_key_file('EC', filename, password)
         self._decode_key(data)
@@ -154,14 +153,14 @@ class ECDSAKey (PKey):
         data = self._read_private_key('EC', file_obj, password)
         self._decode_key(data)
 
-    ALLOWED_PADDINGS = ['\x01', '\x02\x02', '\x03\x03\x03', '\x04\x04\x04\x04',
-                        '\x05\x05\x05\x05\x05', '\x06\x06\x06\x06\x06\x06',
-                        '\x07\x07\x07\x07\x07\x07\x07']
+    ALLOWED_PADDINGS = [one_byte, byte_chr(2) * 2, byte_chr(3) * 3, byte_chr(4) * 4,
+                        byte_chr(5) * 5, byte_chr(6) * 6, byte_chr(7) * 7]
+
     def _decode_key(self, data):
         s, padding = der.remove_sequence(data)
         if padding:
             if padding not in self.ALLOWED_PADDINGS:
-                raise ValueError, "weird padding: %s" % (binascii.hexlify(empty))
+                raise ValueError("weird padding: %s" % u(binascii.hexlify(data)))
             data = data[:-len(padding)]
         key = SigningKey.from_der(data)
         self.signing_key = key
@@ -172,10 +171,10 @@ class ECDSAKey (PKey):
         msg = Message()
         msg.add_mpint(r)
         msg.add_mpint(s)
-        return str(msg)
+        return msg.asbytes()
 
     def _sigdecode(self, sig, order):
         msg = Message(sig)
         r = msg.get_mpint()
         s = msg.get_mpint()
-        return (r, s)
+        return r, s
diff --git a/paramiko/file.py b/paramiko/file.py
index 5fd81cf..2238f0b 100644
--- a/paramiko/file.py
+++ b/paramiko/file.py
@@ -15,17 +15,14 @@
 # You should have received a copy of the GNU Lesser General Public License
 # along with Paramiko; if not, write to the Free Software Foundation, Inc.,
 # 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA.
-
-"""
-BufferedFile.
-"""
-
-from cStringIO import StringIO
+from paramiko.common import linefeed_byte_value, crlf, cr_byte, linefeed_byte, \
+    cr_byte_value
+from paramiko.py3compat import BytesIO, PY2, u, b, bytes_types
 
 
 class BufferedFile (object):
     """
-    Reusable base class to implement python-style file buffering around a
+    Reusable base class to implement Python-style file buffering around a
     simpler stream.
     """
 
@@ -47,8 +44,8 @@ class BufferedFile (object):
         self.newlines = None
         self._flags = 0
         self._bufsize = self._DEFAULT_BUFSIZE
-        self._wbuffer = StringIO()
-        self._rbuffer = ''
+        self._wbuffer = BytesIO()
+        self._rbuffer = bytes()
         self._at_trailing_cr = False
         self._closed = False
         # pos - position within the file, according to the user
@@ -67,10 +64,7 @@ class BufferedFile (object):
         file.  This iterator happens to return the file itself, since a file is
         its own iterator.
 
-        @raise ValueError: if the file is closed.
-        
-        @return: an interator.
-        @rtype: iterator
+        :raises ValueError: if the file is closed.
         """
         if self._closed:
             raise ValueError('I/O operation on closed file')
@@ -89,36 +83,57 @@ class BufferedFile (object):
         buffering is not turned on.
         """
         self._write_all(self._wbuffer.getvalue())
-        self._wbuffer = StringIO()
+        self._wbuffer = BytesIO()
         return
 
-    def next(self):
-        """
-        Returns the next line from the input, or raises L{StopIteration} when
-        EOF is hit.  Unlike python file objects, it's okay to mix calls to
-        C{next} and L{readline}.
+    if PY2:
+        def next(self):
+            """
+            Returns the next line from the input, or raises
+            `~exceptions.StopIteration` when EOF is hit.  Unlike Python file
+            objects, it's okay to mix calls to `next` and `readline`.
 
-        @raise StopIteration: when the end of the file is reached.
+            :raises StopIteration: when the end of the file is reached.
 
-        @return: a line read from the file.
-        @rtype: str
-        """
-        line = self.readline()
-        if not line:
-            raise StopIteration
-        return line
+            :return: a line (`str`) read from the file.
+            """
+            line = self.readline()
+            if not line:
+                raise StopIteration
+            return line
+    else:
+        def __next__(self):
+            """
+            Returns the next line from the input, or raises L{StopIteration} when
+            EOF is hit.  Unlike python file objects, it's okay to mix calls to
+            C{next} and L{readline}.
+
+            @raise StopIteration: when the end of the file is reached.
+
+            @return: a line read from the file.
+            @rtype: str
+            """
+            line = self.readline()
+            if not line:
+                raise StopIteration
+            return line
 
     def read(self, size=None):
         """
-        Read at most C{size} bytes from the file (less if we hit the end of the
-        file first).  If the C{size} argument is negative or omitted, read all
+        Read at most ``size`` bytes from the file (less if we hit the end of the
+        file first).  If the ``size`` argument is negative or omitted, read all
         the remaining data in the file.
 
-        @param size: maximum number of bytes to read
-        @type size: int
-        @return: data read from the file, or an empty string if EOF was
+        .. note::
+            ``'b'`` mode flag is ignored (``self.FLAG_BINARY`` in
+            ``self._flags``), because SSH treats all files as binary, since we
+            have no idea what encoding the file is in, or even if the file is
+            text data.
+
+        :param int size: maximum number of bytes to read
+        :return:
+            data read from the file (as bytes), or an empty string if EOF was
             encountered immediately
-        @rtype: str
         """
         if self._closed:
             raise IOError('File is closed')
@@ -127,7 +142,7 @@ class BufferedFile (object):
         if (size is None) or (size < 0):
             # go for broke
             result = self._rbuffer
-            self._rbuffer = ''
+            self._rbuffer = bytes()
             self._pos += len(result)
             while True:
                 try:
@@ -139,12 +154,12 @@ class BufferedFile (object):
                 result += new_data
                 self._realpos += len(new_data)
                 self._pos += len(new_data)
-            return result
+            return result 
         if size <= len(self._rbuffer):
             result = self._rbuffer[:size]
             self._rbuffer = self._rbuffer[size:]
             self._pos += len(result)
-            return result
+            return result 
         while len(self._rbuffer) < size:
             read_size = size - len(self._rbuffer)
             if self._flags & self.FLAG_BUFFERED:
@@ -160,7 +175,7 @@ class BufferedFile (object):
         result = self._rbuffer[:size]
         self._rbuffer = self._rbuffer[size:]
         self._pos += len(result)
-        return result
+        return result 
 
     def readline(self, size=None):
         """
@@ -171,14 +186,18 @@ class BufferedFile (object):
         incomplete line may be returned.  An empty string is returned only when
         EOF is encountered immediately.
 
-        @note: Unlike stdio's C{fgets()}, the returned string contains null
-        characters (C{'\\0'}) if they occurred in the input.
+        .. note::
+            Unlike stdio's ``fgets``, the returned string contains null
+            characters (``'\\0'``) if they occurred in the input.
 
-        @param size: maximum length of returned string.
-        @type size: int
-        @return: next line of the file, or an empty string if the end of the
+        :param int size: maximum length of returned string.
+        :return:
+            next line of the file, or an empty string if the end of the
             file has been reached.
-        @rtype: str
+
+            If the file was opened in binary (``'b'``) mode: bytes are returned
+            Else: the encoding of the file is assumed to be UTF-8 and character
+            strings (`str`) are returned
         """
         # it's almost silly how complex this function is.
         if self._closed:
@@ -190,11 +209,11 @@ class BufferedFile (object):
             if self._at_trailing_cr and (self._flags & self.FLAG_UNIVERSAL_NEWLINE) and (len(line) > 0):
                 # edge case: the newline may be '\r\n' and we may have read
                 # only the first '\r' last time.
-                if line[0] == '\n':
+                if line[0] == linefeed_byte_value:
                     line = line[1:]
-                    self._record_newline('\r\n')
+                    self._record_newline(crlf)
                 else:
-                    self._record_newline('\r')
+                    self._record_newline(cr_byte)
                 self._at_trailing_cr = False
             # check size before looking for a linefeed, in case we already have
             # enough.
@@ -204,84 +223,82 @@ class BufferedFile (object):
                     self._rbuffer = line[size:]
                     line = line[:size]
                     self._pos += len(line)
-                    return line
+                    return line if self._flags & self.FLAG_BINARY else u(line)
                 n = size - len(line)
             else:
                 n = self._bufsize
-            if ('\n' in line) or ((self._flags & self.FLAG_UNIVERSAL_NEWLINE) and ('\r' in line)):
+            if (linefeed_byte in line) or ((self._flags & self.FLAG_UNIVERSAL_NEWLINE) and (cr_byte in line)):
                 break
             try:
                 new_data = self._read(n)
             except EOFError:
                 new_data = None
             if (new_data is None) or (len(new_data) == 0):
-                self._rbuffer = ''
+                self._rbuffer = bytes()
                 self._pos += len(line)
-                return line
+                return line if self._flags & self.FLAG_BINARY else u(line)
             line += new_data
             self._realpos += len(new_data)
         # find the newline
-        pos = line.find('\n')
+        pos = line.find(linefeed_byte)
         if self._flags & self.FLAG_UNIVERSAL_NEWLINE:
-            rpos = line.find('\r')
-            if (rpos >= 0) and ((rpos < pos) or (pos < 0)):
+            rpos = line.find(cr_byte)
+            if (rpos >= 0) and (rpos < pos or pos < 0):
                 pos = rpos
         xpos = pos + 1
-        if (line[pos] == '\r') and (xpos < len(line)) and (line[xpos] == '\n'):
+        if (line[pos] == cr_byte_value) and (xpos < len(line)) and (line[xpos] == linefeed_byte_value):
             xpos += 1
         self._rbuffer = line[xpos:]
         lf = line[pos:xpos]
-        line = line[:pos] + '\n'
-        if (len(self._rbuffer) == 0) and (lf == '\r'):
+        line = line[:pos] + linefeed_byte
+        if (len(self._rbuffer) == 0) and (lf == cr_byte):
             # we could read the line up to a '\r' and there could still be a
             # '\n' following that we read next time.  note that and eat it.
             self._at_trailing_cr = True
         else:
             self._record_newline(lf)
         self._pos += len(line)
-        return line
+        return line if self._flags & self.FLAG_BINARY else u(line)
 
     def readlines(self, sizehint=None):
         """
-        Read all remaining lines using L{readline} and return them as a list.
-        If the optional C{sizehint} argument is present, instead of reading up
+        Read all remaining lines using `readline` and return them as a list.
+        If the optional ``sizehint`` argument is present, instead of reading up
         to EOF, whole lines totalling approximately sizehint bytes (possibly
         after rounding up to an internal buffer size) are read.
 
-        @param sizehint: desired maximum number of bytes to read.
-        @type sizehint: int
-        @return: list of lines read from the file.
-        @rtype: list
+        :param int sizehint: desired maximum number of bytes to read.
+        :return: `list` of lines read from the file.
         """
         lines = []
-        bytes = 0
+        byte_count = 0
         while True:
             line = self.readline()
             if len(line) == 0:
                 break
             lines.append(line)
-            bytes += len(line)
-            if (sizehint is not None) and (bytes >= sizehint):
+            byte_count += len(line)
+            if (sizehint is not None) and (byte_count >= sizehint):
                 break
         return lines
 
     def seek(self, offset, whence=0):
         """
-        Set the file's current position, like stdio's C{fseek}.  Not all file
+        Set the file's current position, like stdio's ``fseek``.  Not all file
         objects support seeking.
 
-        @note: If a file is opened in append mode (C{'a'} or C{'a+'}), any seek
+        .. note::
+            If a file is opened in append mode (``'a'`` or ``'a+'``), any seek
             operations will be undone at the next write (as the file position
             will move back to the end of the file).
         
-        @param offset: position to move to within the file, relative to
-            C{whence}.
-        @type offset: int
-        @param whence: type of movement: 0 = absolute; 1 = relative to the
-            current position; 2 = relative to the end of the file.
-        @type whence: int
-
-        @raise IOError: if the file doesn't support random access.
+        :param int offset:
+            position to move to within the file, relative to ``whence``.
+        :param int whence:
+            type of movement: 0 = absolute; 1 = relative to the current
+            position; 2 = relative to the end of the file.
+
+        :raises IOError: if the file doesn't support random access.
         """
         raise IOError('File does not support seeking.')
 
@@ -291,21 +308,20 @@ class BufferedFile (object):
         useful if the underlying file doesn't support random access, or was
         opened in append mode.
 
-        @return: file position (in bytes).
-        @rtype: int
+        :return: file position (`number <int>` of bytes).
         """
         return self._pos
 
     def write(self, data):
         """
-        Write data to the file.  If write buffering is on (C{bufsize} was
+        Write data to the file.  If write buffering is on (``bufsize`` was
         specified and non-zero), some or all of the data may not actually be
-        written yet.  (Use L{flush} or L{close} to force buffered data to be
+        written yet.  (Use `flush` or `close` to force buffered data to be
         written out.)
 
-        @param data: data to write.
-        @type data: str
+        :param str data: data to write
         """
+        data = b(data)
         if self._closed:
             raise IOError('File is closed')
         if not (self._flags & self.FLAG_WRITE):
@@ -316,12 +332,12 @@ class BufferedFile (object):
         self._wbuffer.write(data)
         if self._flags & self.FLAG_LINE_BUFFERED:
             # only scan the new data for linefeed, to avoid wasting time.
-            last_newline_pos = data.rfind('\n')
+            last_newline_pos = data.rfind(linefeed_byte)
             if last_newline_pos >= 0:
                 wbuf = self._wbuffer.getvalue()
                 last_newline_pos += len(wbuf) - len(data)
                 self._write_all(wbuf[:last_newline_pos + 1])
-                self._wbuffer = StringIO()
+                self._wbuffer = BytesIO()
                 self._wbuffer.write(wbuf[last_newline_pos + 1:])
             return
         # even if we're line buffering, if the buffer has grown past the
@@ -334,11 +350,10 @@ class BufferedFile (object):
         """
         Write a sequence of strings to the file.  The sequence can be any
         iterable object producing strings, typically a list of strings.  (The
-        name is intended to match L{readlines}; C{writelines} does not add line
+        name is intended to match `readlines`; `writelines` does not add line
         separators.)
 
-        @param sequence: an iterable sequence of strings.
-        @type sequence: sequence
+        :param iterable sequence: an iterable sequence of strings.
         """
         for line in sequence:
             self.write(line)
@@ -346,11 +361,8 @@ class BufferedFile (object):
 
     def xreadlines(self):
         """
-        Identical to C{iter(f)}.  This is a deprecated file interface that
-        predates python iterator support.
-
-        @return: an iterator.
-        @rtype: iterator
+        Identical to ``iter(f)``.  This is a deprecated file interface that
+        predates Python iterator support.
         """
         return self
 
@@ -358,40 +370,36 @@ class BufferedFile (object):
     def closed(self):
         return self._closed
 
-
     ###  overrides...
 
-
     def _read(self, size):
         """
-        I{(subclass override)}
-        Read data from the stream.  Return C{None} or raise C{EOFError} to
+        (subclass override)
+        Read data from the stream.  Return ``None`` or raise ``EOFError`` to
         indicate EOF.
         """
         raise EOFError()
 
     def _write(self, data):
         """
-        I{(subclass override)}
+        (subclass override)
         Write data into the stream.
         """
         raise IOError('write not implemented')
 
     def _get_size(self):
         """
-        I{(subclass override)}
-        Return the size of the file.  This is called from within L{_set_mode}
+        (subclass override)
+        Return the size of the file.  This is called from within `_set_mode`
         if the file is opened in append mode, so the file position can be
-        tracked and L{seek} and L{tell} will work correctly.  If the file is
+        tracked and `seek` and `tell` will work correctly.  If the file is
         a stream that can't be randomly accessed, you don't need to override
         this method,
         """
         return 0
 
-
     ###  internals...
 
-
     def _set_mode(self, mode='r', bufsize=-1):
         """
         Subclasses call this method to initialize the BufferedFile.
@@ -419,13 +427,13 @@ class BufferedFile (object):
             self._flags |= self.FLAG_READ
         if ('w' in mode) or ('+' in mode):
             self._flags |= self.FLAG_WRITE
-        if ('a' in mode):
+        if 'a' in mode:
             self._flags |= self.FLAG_WRITE | self.FLAG_APPEND
             self._size = self._get_size()
             self._pos = self._realpos = self._size
-        if ('b' in mode):
+        if 'b' in mode:
             self._flags |= self.FLAG_BINARY
-        if ('U' in mode):
+        if 'U' in mode:
             self._flags |= self.FLAG_UNIVERSAL_NEWLINE
             # built-in file objects have this attribute to store which kinds of
             # line terminations they've seen:
@@ -454,7 +462,7 @@ class BufferedFile (object):
             return
         if self.newlines is None:
             self.newlines = newline
-        elif (type(self.newlines) is str) and (self.newlines != newline):
+        elif self.newlines != newline and isinstance(self.newlines, bytes_types):
             self.newlines = (self.newlines, newline)
         elif newline not in self.newlines:
             self.newlines += (newline,)
diff --git a/paramiko/hostkeys.py b/paramiko/hostkeys.py
index 9bcf0d5..c0caeda 100644
--- a/paramiko/hostkeys.py
+++ b/paramiko/hostkeys.py
@@ -16,118 +16,45 @@
 # along with Paramiko; if not, write to the Free Software Foundation, Inc.,
 # 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA.
 
-"""
-L{HostKeys}
-"""
 
-import base64
 import binascii
-from Crypto.Hash import SHA, HMAC
-import UserDict
-
-from paramiko.common import *
-from paramiko.dsskey import DSSKey
-from paramiko.rsakey import RSAKey
-from paramiko.util import get_logger
-from paramiko.ecdsakey import ECDSAKey
-
-
-class InvalidHostKey(Exception):
-
-    def __init__(self, line, exc):
-        self.line = line
-        self.exc = exc
-        self.args = (line, exc)
+import os
 
+from hashlib import sha1
+from hmac import HMAC
 
-class HostKeyEntry:
-    """
-    Representation of a line in an OpenSSH-style "known hosts" file.
-    """
+from paramiko.py3compat import b, u, encodebytes, decodebytes
 
-    def __init__(self, hostnames=None, key=None):
-        self.valid = (hostnames is not None) and (key is not None)
-        self.hostnames = hostnames
-        self.key = key
-
-    def from_line(cls, line, lineno=None):
-        """
-        Parses the given line of text to find the names for the host,
-        the type of key, and the key data. The line is expected to be in the
-        format used by the openssh known_hosts file.
-
-        Lines are expected to not have leading or trailing whitespace.
-        We don't bother to check for comments or empty lines.  All of
-        that should be taken care of before sending the line to us.
-
-        @param line: a line from an OpenSSH known_hosts file
-        @type line: str
-        """
-        log = get_logger('paramiko.hostkeys')
-        fields = line.split(' ')
-        if len(fields) < 3:
-            # Bad number of fields
-            log.info("Not enough fields found in known_hosts in line %s (%r)" %
-                     (lineno, line))
-            return None
-        fields = fields[:3]
+try:
+    from collections import MutableMapping
+except ImportError:
+    # noinspection PyUnresolvedReferences
+    from UserDict import DictMixin as MutableMapping
 
-        names, keytype, key = fields
-        names = names.split(',')
-
-        # Decide what kind of key we're looking at and create an object
-        # to hold it accordingly.
-        try:
-            if keytype == 'ssh-rsa':
-                key = RSAKey(data=base64.decodestring(key))
-            elif keytype == 'ssh-dss':
-                key = DSSKey(data=base64.decodestring(key))
-            elif keytype == 'ecdsa-sha2-nistp256':
-                key = ECDSAKey(data=base64.decodestring(key))
-            else:
-                log.info("Unable to handle key of type %s" % (keytype,))
-                return None
-
-        except binascii.Error, e:
-            raise InvalidHostKey(line, e)
-
-        return cls(names, key)
-    from_line = classmethod(from_line)
-
-    def to_line(self):
-        """
-        Returns a string in OpenSSH known_hosts file format, or None if
-        the object is not in a valid state.  A trailing newline is
-        included.
-        """
-        if self.valid:
-            return '%s %s %s\n' % (','.join(self.hostnames), self.key.get_name(),
-                   self.key.get_base64())
-        return None
-
-    def __repr__(self):
-        return '<HostKeyEntry %r: %r>' % (self.hostnames, self.key)
+from paramiko.dsskey import DSSKey
+from paramiko.rsakey import RSAKey
+from paramiko.util import get_logger, constant_time_bytes_eq
+from paramiko.ecdsakey import ECDSAKey
 
 
-class HostKeys (UserDict.DictMixin):
+class HostKeys (MutableMapping):
     """
-    Representation of an openssh-style "known hosts" file.  Host keys can be
+    Representation of an OpenSSH-style "known hosts" file.  Host keys can be
     read from one or more files, and then individual hosts can be looked up to
     verify server keys during SSH negotiation.
 
-    A HostKeys object can be treated like a dict; any dict lookup is equivalent
-    to calling L{lookup}.
+    A `.HostKeys` object can be treated like a dict; any dict lookup is
+    equivalent to calling `lookup`.
 
-    @since: 1.5.3
+    .. versionadded:: 1.5.3
     """
 
     def __init__(self, filename=None):
         """
-        Create a new HostKeys object, optionally loading keys from an openssh
+        Create a new HostKeys object, optionally loading keys from an OpenSSH
         style host-key file.
 
-        @param filename: filename to load host keys from, or C{None}
-        @type filename: str
+        :param str filename: filename to load host keys from, or ``None``
         """
         # emulate a dict of { hostname: { keytype: PKey } }
         self._entries = []
@@ -137,14 +64,11 @@ class HostKeys (UserDict.DictMixin):
     def add(self, hostname, keytype, key):
         """
         Add a host key entry to the table.  Any existing entry for a
-        C{(hostname, keytype)} pair will be replaced.
-
-        @param hostname: the hostname (or IP) to add
-        @type hostname: str
-        @param keytype: key type (C{"ssh-rsa"} or C{"ssh-dss"})
-        @type keytype: str
-        @param key: the key to add
-        @type key: L{PKey}
+        ``(hostname, keytype)`` pair will be replaced.
+
+        :param str hostname: the hostname (or IP) to add
+        :param str keytype: key type (``"ssh-rsa"`` or ``"ssh-dss"``)
+        :param .PKey key: the key to add
         """
         for e in self._entries:
             if (hostname in e.hostnames) and (e.key.get_name() == keytype):
@@ -154,73 +78,81 @@ class HostKeys (UserDict.DictMixin):
 
     def load(self, filename):
         """
-        Read a file of known SSH host keys, in the format used by openssh.
+        Read a file of known SSH host keys, in the format used by OpenSSH.
         This type of file unfortunately doesn't exist on Windows, but on
         posix, it will usually be stored in
-        C{os.path.expanduser("~/.ssh/known_hosts")}.
+        ``os.path.expanduser("~/.ssh/known_hosts")``.
 
         If this method is called multiple times, the host keys are merged,
-        not cleared.  So multiple calls to C{load} will just call L{add},
+        not cleared.  So multiple calls to `load` will just call `add`,
         replacing any existing entries and adding new ones.
 
-        @param filename: name of the file to read host keys from
-        @type filename: str
+        :param str filename: name of the file to read host keys from
 
-        @raise IOError: if there was an error reading the file
+        :raises IOError: if there was an error reading the file
         """
-        f = open(filename, 'r')
-        for lineno, line in enumerate(f):
-            line = line.strip()
-            if (len(line) == 0) or (line[0] == '#'):
-                continue
-            e = HostKeyEntry.from_line(line, lineno)
-            if e is not None:
-                _hostnames = e.hostnames
-                for h in _hostnames:
-                    if self.check(h, e.key):
-                        e.hostnames.remove(h)
-                if len(e.hostnames):
-                    self._entries.append(e)
-        f.close()
+        with open(filename, 'r') as f:
+            for lineno, line in enumerate(f):
+                line = line.strip()
+                if (len(line) == 0) or (line[0] == '#'):
+                    continue
+                e = HostKeyEntry.from_line(line, lineno)
+                if e is not None:
+                    _hostnames = e.hostnames
+                    for h in _hostnames:
+                        if self.check(h, e.key):
+                            e.hostnames.remove(h)
+                    if len(e.hostnames):
+                        self._entries.append(e)
 
     def save(self, filename):
         """
-        Save host keys into a file, in the format used by openssh.  The order of
+        Save host keys into a file, in the format used by OpenSSH.  The order of
         keys in the file will be preserved when possible (if these keys were
         loaded from a file originally).  The single exception is that combined
         lines will be split into individual key lines, which is arguably a bug.
 
-        @param filename: name of the file to write
-        @type filename: str
+        :param str filename: name of the file to write
 
-        @raise IOError: if there was an error writing the file
+        :raises IOError: if there was an error writing the file
 
-        @since: 1.6.1
+        .. versionadded:: 1.6.1
         """
-        f = open(filename, 'w')
-        for e in self._entries:
-            line = e.to_line()
-            if line:
-                f.write(line)
-        f.close()
+        with open(filename, 'w') as f:
+            for e in self._entries:
+                line = e.to_line()
+                if line:
+                    f.write(line)
 
     def lookup(self, hostname):
         """
         Find a hostkey entry for a given hostname or IP.  If no entry is found,
-        C{None} is returned.  Otherwise a dictionary of keytype to key is
-        returned.  The keytype will be either C{"ssh-rsa"} or C{"ssh-dss"}.
+        ``None`` is returned.  Otherwise a dictionary of keytype to key is
+        returned.  The keytype will be either ``"ssh-rsa"`` or ``"ssh-dss"``.
 
-        @param hostname: the hostname (or IP) to lookup
-        @type hostname: str
-        @return: keys associated with this host (or C{None})
-        @rtype: dict(str, L{PKey})
+        :param str hostname: the hostname (or IP) to lookup
+        :return: dict of `str` -> `.PKey` keys associated with this host (or ``None``)
         """
-        class SubDict (UserDict.DictMixin):
+        class SubDict (MutableMapping):
             def __init__(self, hostname, entries, hostkeys):
                 self._hostname = hostname
                 self._entries = entries
                 self._hostkeys = hostkeys
 
+            def __iter__(self):
+                for k in self.keys():
+                    yield k
+
+            def __len__(self):
+                return len(self.keys())
+
+            def __delitem__(self, key):
+                for e in list(self._entries):
+                    if e.key.get_name() == key:
+                        self._entries.remove(e)
+                else:
+                    raise KeyError(key)
+
             def __getitem__(self, key):
                 for e in self._entries:
                     if e.key.get_name() == key:
@@ -247,7 +179,7 @@ class HostKeys (UserDict.DictMixin):
         entries = []
         for e in self._entries:
             for h in e.hostnames:
-                if (h.startswith('|1|') and (self.hash_host(hostname, h) == h)) or (h == hostname):
+                if h.startswith('|1|') and constant_time_bytes_eq(self.hash_host(hostname, h), h) or h == hostname:
                     entries.append(e)
         if len(entries) == 0:
             return None
@@ -258,13 +190,10 @@ class HostKeys (UserDict.DictMixin):
         Return True if the given key is associated with the given hostname
         in this dictionary.
 
-        @param hostname: hostname (or IP) of the SSH server
-        @type hostname: str
-        @param key: the key to check
-        @type key: L{PKey}
-        @return: C{True} if the key is associated with the hostname; C{False}
-            if not
-        @rtype: bool
+        :param str hostname: hostname (or IP) of the SSH server
+        :param .PKey key: the key to check
+        :return:
+            ``True`` if the key is associated with the hostname; else ``False``
         """
         k = self.lookup(hostname)
         if k is None:
@@ -272,7 +201,7 @@ class HostKeys (UserDict.DictMixin):
         host_key = k.get(key.get_name(), None)
         if host_key is None:
             return False
-        return str(host_key) == str(key)
+        return host_key.asbytes() == key.asbytes()
 
     def clear(self):
         """
@@ -280,6 +209,16 @@ class HostKeys (UserDict.DictMixin):
         """
         self._entries = []
 
+    def __iter__(self):
+        for k in self.keys():
+            yield k
+
+    def __len__(self):
+        return len(self.keys())
+
+    def __delitem__(self, key):
+        k = self[key]
+
     def __getitem__(self, key):
         ret = self.lookup(key)
         if ret is None:
@@ -302,7 +241,7 @@ class HostKeys (UserDict.DictMixin):
                 self._entries.append(HostKeyEntry([hostname], entry[key_type]))
 
     def keys(self):
-        # python 2.4 sets would be nice here.
+        # Python 2.4 sets would be nice here.
         ret = []
         for e in self._entries:
             for h in e.hostnames:
@@ -318,25 +257,97 @@ class HostKeys (UserDict.DictMixin):
 
     def hash_host(hostname, salt=None):
         """
-        Return a "hashed" form of the hostname, as used by openssh when storing
+        Return a "hashed" form of the hostname, as used by OpenSSH when storing
         hashed hostnames in the known_hosts file.
 
-        @param hostname: the hostname to hash
-        @type hostname: str
-        @param salt: optional salt to use when hashing (must be 20 bytes long)
-        @type salt: str
-        @return: the hashed hostname
-        @rtype: str
+        :param str hostname: the hostname to hash
+        :param str salt: optional salt to use when hashing (must be 20 bytes long)
+        :return: the hashed hostname as a `str`
         """
         if salt is None:
-            salt = rng.read(SHA.digest_size)
+            salt = os.urandom(sha1().digest_size)
         else:
             if salt.startswith('|1|'):
                 salt = salt.split('|')[2]
-            salt = base64.decodestring(salt)
-        assert len(salt) == SHA.digest_size
-        hmac = HMAC.HMAC(salt, hostname, SHA).digest()
-        hostkey = '|1|%s|%s' % (base64.encodestring(salt), base64.encodestring(hmac))
+            salt = decodebytes(b(salt))
+        assert len(salt) == sha1().digest_size
+        hmac = HMAC(salt, b(hostname), sha1).digest()
+        hostkey = '|1|%s|%s' % (u(encodebytes(salt)), u(encodebytes(hmac)))
         return hostkey.replace('\n', '')
     hash_host = staticmethod(hash_host)
 
+
+class InvalidHostKey(Exception):
+    def __init__(self, line, exc):
+        self.line = line
+        self.exc = exc
+        self.args = (line, exc)
+
+
+class HostKeyEntry:
+    """
+    Representation of a line in an OpenSSH-style "known hosts" file.
+    """
+
+    def __init__(self, hostnames=None, key=None):
+        self.valid = (hostnames is not None) and (key is not None)
+        self.hostnames = hostnames
+        self.key = key
+
+    def from_line(cls, line, lineno=None):
+        """
+        Parses the given line of text to find the names for the host,
+        the type of key, and the key data. The line is expected to be in the
+        format used by the OpenSSH known_hosts file.
+
+        Lines are expected to not have leading or trailing whitespace.
+        We don't bother to check for comments or empty lines.  All of
+        that should be taken care of before sending the line to us.
+
+        :param str line: a line from an OpenSSH known_hosts file
+        """
+        log = get_logger('paramiko.hostkeys')
+        fields = line.split(' ')
+        if len(fields) < 3:
+            # Bad number of fields
+            log.info("Not enough fields found in known_hosts in line %s (%r)" %
+                     (lineno, line))
+            return None
+        fields = fields[:3]
+
+        names, keytype, key = fields
+        names = names.split(',')
+
+        # Decide what kind of key we're looking at and create an object
+        # to hold it accordingly.
+        try:
+            key = b(key)
+            if keytype == 'ssh-rsa':
+                key = RSAKey(data=decodebytes(key))
+            elif keytype == 'ssh-dss':
+                key = DSSKey(data=decodebytes(key))
+            elif keytype == 'ecdsa-sha2-nistp256':
+                key = ECDSAKey(data=decodebytes(key))
+            else:
+                log.info("Unable to handle key of type %s" % (keytype,))
+                return None
+
+        except binascii.Error as e:
+            raise InvalidHostKey(line, e)
+
+        return cls(names, key)
+    from_line = classmethod(from_line)
+
+    def to_line(self):
+        """
+        Returns a string in OpenSSH known_hosts file format, or None if
+        the object is not in a valid state.  A trailing newline is
+        included.
+        """
+        if self.valid:
+            return '%s %s %s\n' % (','.join(self.hostnames), self.key.get_name(),
+                   self.key.get_base64())
+        return None
+
+    def __repr__(self):
+        return '<HostKeyEntry %r: %r>' % (self.hostnames, self.key)
diff --git a/paramiko/kex_gex.py b/paramiko/kex_gex.py
index c0455a1..5ff8a28 100644
--- a/paramiko/kex_gex.py
+++ b/paramiko/kex_gex.py
@@ -17,22 +17,25 @@
 # 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA.
 
 """
-Variant on L{KexGroup1 <paramiko.kex_group1.KexGroup1>} where the prime "p" and
+Variant on `KexGroup1 <paramiko.kex_group1.KexGroup1>` where the prime "p" and
 generator "g" are provided by the server.  A bit more work is required on the
 client side, and a B{lot} more on the server side.
 """
 
-from Crypto.Hash import SHA
-from Crypto.Util import number
+import os
+from hashlib import sha1
 
-from paramiko.common import *
 from paramiko import util
+from paramiko.common import DEBUG
 from paramiko.message import Message
+from paramiko.py3compat import byte_chr, byte_ord, byte_mask
 from paramiko.ssh_exception import SSHException
 
 
 _MSG_KEXDH_GEX_REQUEST_OLD, _MSG_KEXDH_GEX_GROUP, _MSG_KEXDH_GEX_INIT, \
     _MSG_KEXDH_GEX_REPLY, _MSG_KEXDH_GEX_REQUEST = range(30, 35)
+c_MSG_KEXDH_GEX_REQUEST_OLD, c_MSG_KEXDH_GEX_GROUP, c_MSG_KEXDH_GEX_INIT, \
+    c_MSG_KEXDH_GEX_REPLY, c_MSG_KEXDH_GEX_REQUEST = [byte_chr(c) for c in range(30, 35)]
 
 
 class KexGex (object):
@@ -62,11 +65,11 @@ class KexGex (object):
         m = Message()
         if _test_old_style:
             # only used for unit tests: we shouldn't ever send this
-            m.add_byte(chr(_MSG_KEXDH_GEX_REQUEST_OLD))
+            m.add_byte(c_MSG_KEXDH_GEX_REQUEST_OLD)
             m.add_int(self.preferred_bits)
             self.old_style = True
         else:
-            m.add_byte(chr(_MSG_KEXDH_GEX_REQUEST))
+            m.add_byte(c_MSG_KEXDH_GEX_REQUEST)
             m.add_int(self.min_bits)
             m.add_int(self.preferred_bits)
             m.add_int(self.max_bits)
@@ -86,23 +89,21 @@ class KexGex (object):
             return self._parse_kexdh_gex_request_old(m)
         raise SSHException('KexGex asked to handle packet type %d' % ptype)
 
-
     ###  internals...
 
-    
     def _generate_x(self):
         # generate an "x" (1 < x < (p-1)/2).
         q = (self.p - 1) // 2
         qnorm = util.deflate_long(q, 0)
-        qhbyte = ord(qnorm[0])
-        bytes = len(qnorm)
+        qhbyte = byte_ord(qnorm[0])
+        byte_count = len(qnorm)
         qmask = 0xff
         while not (qhbyte & 0x80):
             qhbyte <<= 1
             qmask >>= 1
         while True:
-            x_bytes = self.transport.rng.read(bytes)
-            x_bytes = chr(ord(x_bytes[0]) & qmask) + x_bytes[1:]
+            x_bytes = os.urandom(byte_count)
+            x_bytes = byte_mask(x_bytes[0], qmask) + x_bytes[1:]
             x = util.inflate_long(x_bytes, 1)
             if (x > 1) and (x < q):
                 break
@@ -135,7 +136,7 @@ class KexGex (object):
         self.transport._log(DEBUG, 'Picking p (%d <= %d <= %d bits)' % (minbits, preferredbits, maxbits))
         self.g, self.p = pack.get_modulus(minbits, preferredbits, maxbits)
         m = Message()
-        m.add_byte(chr(_MSG_KEXDH_GEX_GROUP))
+        m.add_byte(c_MSG_KEXDH_GEX_GROUP)
         m.add_mpint(self.p)
         m.add_mpint(self.g)
         self.transport._send_message(m)
@@ -156,7 +157,7 @@ class KexGex (object):
         self.transport._log(DEBUG, 'Picking p (~ %d bits)' % (self.preferred_bits,))
         self.g, self.p = pack.get_modulus(self.min_bits, self.preferred_bits, self.max_bits)
         m = Message()
-        m.add_byte(chr(_MSG_KEXDH_GEX_GROUP))
+        m.add_byte(c_MSG_KEXDH_GEX_GROUP)
         m.add_mpint(self.p)
         m.add_mpint(self.g)
         self.transport._send_message(m)
@@ -175,7 +176,7 @@ class KexGex (object):
         # now compute e = g^x mod p
         self.e = pow(self.g, self.x, self.p)
         m = Message()
-        m.add_byte(chr(_MSG_KEXDH_GEX_INIT))
+        m.add_byte(c_MSG_KEXDH_GEX_INIT)
         m.add_mpint(self.e)
         self.transport._send_message(m)
         self.transport._expect_packet(_MSG_KEXDH_GEX_REPLY)
@@ -187,7 +188,7 @@ class KexGex (object):
         self._generate_x()
         self.f = pow(self.g, self.x, self.p)
         K = pow(self.e, self.x, self.p)
-        key = str(self.transport.get_server_key())
+        key = self.transport.get_server_key().asbytes()
         # okay, build up the hash H of (V_C || V_S || I_C || I_S || K_S || min || n || max || p || g || e || f || K)
         hm = Message()
         hm.add(self.transport.remote_version, self.transport.local_version,
@@ -203,19 +204,19 @@ class KexGex (object):
         hm.add_mpint(self.e)
         hm.add_mpint(self.f)
         hm.add_mpint(K)
-        H = SHA.new(str(hm)).digest()
+        H = sha1(hm.asbytes()).digest()
         self.transport._set_K_H(K, H)
         # sign it
-        sig = self.transport.get_server_key().sign_ssh_data(self.transport.rng, H)
+        sig = self.transport.get_server_key().sign_ssh_data(H)
         # send reply
         m = Message()
-        m.add_byte(chr(_MSG_KEXDH_GEX_REPLY))
+        m.add_byte(c_MSG_KEXDH_GEX_REPLY)
         m.add_string(key)
         m.add_mpint(self.f)
-        m.add_string(str(sig))
+        m.add_string(sig)
         self.transport._send_message(m)
         self.transport._activate_outbound()
-        
+
     def _parse_kexdh_gex_reply(self, m):
         host_key = m.get_string()
         self.f = m.get_mpint()
@@ -238,6 +239,6 @@ class KexGex (object):
         hm.add_mpint(self.e)
         hm.add_mpint(self.f)
         hm.add_mpint(K)
-        self.transport._set_K_H(K, SHA.new(str(hm)).digest())
+        self.transport._set_K_H(K, sha1(hm.asbytes()).digest())
         self.transport._verify_key(host_key, sig)
         self.transport._activate_outbound()
diff --git a/paramiko/kex_group1.py b/paramiko/kex_group1.py
index 6e89b6d..7ccceea 100644
--- a/paramiko/kex_group1.py
+++ b/paramiko/kex_group1.py
@@ -21,20 +21,26 @@ Standard SSH key exchange ("kex" if you wanna sound cool).  Diffie-Hellman of
 1024 bit key halves, using a known "p" prime and "g" generator.
 """
 
-from Crypto.Hash import SHA
+import os
+from hashlib import sha1
 
-from paramiko.common import *
 from paramiko import util
+from paramiko.common import max_byte, zero_byte
 from paramiko.message import Message
+from paramiko.py3compat import byte_chr, long, byte_mask
 from paramiko.ssh_exception import SSHException
 
 
 _MSG_KEXDH_INIT, _MSG_KEXDH_REPLY = range(30, 32)
+c_MSG_KEXDH_INIT, c_MSG_KEXDH_REPLY = [byte_chr(c) for c in range(30, 32)]
 
 # draft-ietf-secsh-transport-09.txt, page 17
-P = 0xFFFFFFFFFFFFFFFFC90FDAA22168C234C4C6628B80DC1CD129024E088A67CC74020BBEA63B139B22514A08798E3404DDEF9519B3CD3A431B302B0A6DF25F14374FE1356D6D51C245E485B576625E7EC6F44C42E9A637ED6B0BFF5CB6F406B7EDEE386BFB5A899FA5AE9F24117C4B1FE649286651ECE65381FFFFFFFFFFFFFFFFL
+P = 0xFFFFFFFFFFFFFFFFC90FDAA22168C234C4C6628B80DC1CD129024E088A67CC74020BBEA63B139B22514A08798E3404DDEF9519B3CD3A431B302B0A6DF25F14374FE1356D6D51C245E485B576625E7EC6F44C42E9A637ED6B0BFF5CB6F406B7EDEE386BFB5A899FA5AE9F24117C4B1FE649286651ECE65381FFFFFFFFFFFFFFFF
 G = 2
 
+b7fffffffffffffff = byte_chr(0x7f) + max_byte * 7
+b0000000000000000 = zero_byte * 8
+
 
 class KexGroup1(object):
 
@@ -42,9 +48,9 @@ class KexGroup1(object):
 
     def __init__(self, transport):
         self.transport = transport
-        self.x = 0L
-        self.e = 0L
-        self.f = 0L
+        self.x = long(0)
+        self.e = long(0)
+        self.f = long(0)
 
     def start_kex(self):
         self._generate_x()
@@ -56,7 +62,7 @@ class KexGroup1(object):
         # compute e = g^x mod p (where g=2), and send it
         self.e = pow(G, self.x, P)
         m = Message()
-        m.add_byte(chr(_MSG_KEXDH_INIT))
+        m.add_byte(c_MSG_KEXDH_INIT)
         m.add_mpint(self.e)
         self.transport._send_message(m)
         self.transport._expect_packet(_MSG_KEXDH_REPLY)
@@ -67,11 +73,9 @@ class KexGroup1(object):
         elif not self.transport.server_mode and (ptype == _MSG_KEXDH_REPLY):
             return self._parse_kexdh_reply(m)
         raise SSHException('KexGroup1 asked to handle packet type %d' % ptype)
-    
 
     ###  internals...
 
-
     def _generate_x(self):
         # generate an "x" (1 < x < q), where q is (p-1)/2.
         # p is a 128-byte (1024-bit) number, where the first 64 bits are 1. 
@@ -79,10 +83,10 @@ class KexGroup1(object):
         # potential x where the first 63 bits are 1, because some of those will be
         # larger than q (but this is a tiny tiny subset of potential x).
         while 1:
-            x_bytes = self.transport.rng.read(128)
-            x_bytes = chr(ord(x_bytes[0]) & 0x7f) + x_bytes[1:]
-            if (x_bytes[:8] != '\x7F\xFF\xFF\xFF\xFF\xFF\xFF\xFF') and \
-                   (x_bytes[:8] != '\x00\x00\x00\x00\x00\x00\x00\x00'):
+            x_bytes = os.urandom(128)
+            x_bytes = byte_mask(x_bytes[0], 0x7f) + x_bytes[1:]
+            if (x_bytes[:8] != b7fffffffffffffff and
+                    x_bytes[:8] != b0000000000000000):
                 break
         self.x = util.inflate_long(x_bytes)
 
@@ -92,7 +96,7 @@ class KexGroup1(object):
         self.f = m.get_mpint()
         if (self.f < 1) or (self.f > P - 1):
             raise SSHException('Server kex "f" is out of range')
-        sig = m.get_string()
+        sig = m.get_binary()
         K = pow(self.f, self.x, P)
         # okay, build up the hash H of (V_C || V_S || I_C || I_S || K_S || e || f || K)
         hm = Message()
@@ -102,7 +106,7 @@ class KexGroup1(object):
         hm.add_mpint(self.e)
         hm.add_mpint(self.f)
         hm.add_mpint(K)
-        self.transport._set_K_H(K, SHA.new(str(hm)).digest())
+        self.transport._set_K_H(K, sha1(hm.asbytes()).digest())
         self.transport._verify_key(host_key, sig)
         self.transport._activate_outbound()
 
@@ -112,7 +116,7 @@ class KexGroup1(object):
         if (self.e < 1) or (self.e > P - 1):
             raise SSHException('Client kex "e" is out of range')
         K = pow(self.e, self.x, P)
-        key = str(self.transport.get_server_key())
+        key = self.transport.get_server_key().asbytes()
         # okay, build up the hash H of (V_C || V_S || I_C || I_S || K_S || e || f || K)
         hm = Message()
         hm.add(self.transport.remote_version, self.transport.local_version,
@@ -121,15 +125,15 @@ class KexGroup1(object):
         hm.add_mpint(self.e)
         hm.add_mpint(self.f)
         hm.add_mpint(K)
-        H = SHA.new(str(hm)).digest()
+        H = sha1(hm.asbytes()).digest()
         self.transport._set_K_H(K, H)
         # sign it
-        sig = self.transport.get_server_key().sign_ssh_data(self.transport.rng, H)
+        sig = self.transport.get_server_key().sign_ssh_data(H)
         # send reply
         m = Message()
-        m.add_byte(chr(_MSG_KEXDH_REPLY))
+        m.add_byte(c_MSG_KEXDH_REPLY)
         m.add_string(key)
         m.add_mpint(self.f)
-        m.add_string(str(sig))
+        m.add_string(sig)
         self.transport._send_message(m)
         self.transport._activate_outbound()
diff --git a/paramiko/logging22.py b/paramiko/logging22.py
deleted file mode 100644
index e68c52c..0000000
--- a/paramiko/logging22.py
+++ /dev/null
@@ -1,66 +0,0 @@
-# Copyright (C) 2003-2007  Robey Pointer <robeypointer@gmail.com>
-#
-# This file is part of paramiko.
-#
-# Paramiko is free software; you can redistribute it and/or modify it under the
-# terms of the GNU Lesser General Public License as published by the Free
-# Software Foundation; either version 2.1 of the License, or (at your option)
-# any later version.
-#
-# Paramiko is distributed in the hope that it will be useful, but WITHOUT ANY
-# WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
-# A PARTICULAR PURPOSE.  See the GNU Lesser General Public License for more
-# details.
-#
-# You should have received a copy of the GNU Lesser General Public License
-# along with Paramiko; if not, write to the Free Software Foundation, Inc.,
-# 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA.
-
-"""
-Stub out logging on python < 2.3.
-"""
-
-
-DEBUG = 10
-INFO = 20
-WARNING = 30
-ERROR = 40
-CRITICAL = 50
-
-
-def getLogger(name):
-    return _logger
-
-
-class logger (object):
-    def __init__(self):
-        self.handlers = [ ]
-        self.level = ERROR
-
-    def setLevel(self, level):
-        self.level = level
-
-    def addHandler(self, h):
-        self.handlers.append(h)
-
-    def addFilter(self, filter):
-        pass
-        
-    def log(self, level, text):
-        if level >= self.level:
-            for h in self.handlers:
-                h.f.write(text + '\n')
-                h.f.flush()
-
-class StreamHandler (object):
-    def __init__(self, f):
-        self.f = f
-
-    def setFormatter(self, f):
-        pass
-
-class Formatter (object):
-    def __init__(self, x, y):
-        pass
-
-_logger = logger()
diff --git a/paramiko/message.py b/paramiko/message.py
index c0e8692..da6acf8 100644
--- a/paramiko/message.py
+++ b/paramiko/message.py
@@ -21,52 +21,56 @@ Implementation of an SSH2 "message".
 """
 
 import struct
-import cStringIO
 
 from paramiko import util
+from paramiko.common import zero_byte, max_byte, one_byte, asbytes
+from paramiko.py3compat import long, BytesIO, u, integer_types
 
 
 class Message (object):
     """
-    An SSH2 I{Message} is a stream of bytes that encodes some combination of
-    strings, integers, bools, and infinite-precision integers (known in python
-    as I{long}s).  This class builds or breaks down such a byte stream.
+    An SSH2 message is a stream of bytes that encodes some combination of
+    strings, integers, bools, and infinite-precision integers (known in Python
+    as longs).  This class builds or breaks down such a byte stream.
     
     Normally you don't need to deal with anything this low-level, but it's
     exposed for people implementing custom extensions, or features that
     paramiko doesn't support yet.
     """
 
+    big_int = long(0xff000000)
+
     def __init__(self, content=None):
         """
-        Create a new SSH2 Message.
+        Create a new SSH2 message.
 
-        @param content: the byte stream to use as the Message content (passed
-            in only when decomposing a Message).
-        @type content: string
+        :param str content:
+            the byte stream to use as the message content (passed in only when
+            decomposing a message).
         """
-        if content != None:
-            self.packet = cStringIO.StringIO(content)
+        if content is not None:
+            self.packet = BytesIO(content)
         else:
-            self.packet = cStringIO.StringIO()
+            self.packet = BytesIO()
 
     def __str__(self):
         """
-        Return the byte stream content of this Message, as a string.
-
-        @return: the contents of this Message.
-        @rtype: string
+        Return the byte stream content of this message, as a string/bytes obj.
         """
-        return self.packet.getvalue()
+        return self.asbytes()
 
     def __repr__(self):
         """
         Returns a string representation of this object, for debugging.
-
-        @rtype: string
         """
         return 'paramiko.Message(' + repr(self.packet.getvalue()) + ')'
 
+    def asbytes(self):
+        """
+        Return the byte stream content of this Message, as bytes.
+        """
+        return self.packet.getvalue()
+
     def rewind(self):
         """
         Rewind the message to the beginning as if no items had been parsed
@@ -76,11 +80,8 @@ class Message (object):
 
     def get_remainder(self):
         """
-        Return the bytes of this Message that haven't already been parsed and
-        returned.
-
-        @return: a string of the bytes not parsed yet.
-        @rtype: string
+        Return the bytes (as a `str`) of this message that haven't already been
+        parsed and returned.
         """
         position = self.packet.tell()
         remainder = self.packet.read()
@@ -89,12 +90,9 @@ class Message (object):
 
     def get_so_far(self):
         """
-        Returns the bytes of this Message that have been parsed and returned.
-        The string passed into a Message's constructor can be regenerated by
-        concatenating C{get_so_far} and L{get_remainder}.
-
-        @return: a string of the bytes parsed so far.
-        @rtype: string
+        Returns the `str` bytes of this message that have been parsed and
+        returned. The string passed into a message's constructor can be
+        regenerated by concatenating ``get_so_far`` and `get_remainder`.
         """
         position = self.packet.tell()
         self.rewind()
@@ -102,44 +100,51 @@ class Message (object):
 
     def get_bytes(self, n):
         """
-        Return the next C{n} bytes of the Message, without decomposing into
-        an int, string, etc.  Just the raw bytes are returned.
-
-        @return: a string of the next C{n} bytes of the Message, or a string
-            of C{n} zero bytes, if there aren't C{n} bytes remaining.
-        @rtype: string
+        Return the next ``n`` bytes of the message (as a `str`), without
+        decomposing into an int, decoded string, etc.  Just the raw bytes are
+        returned. Returns a string of ``n`` zero bytes if there weren't ``n``
+        bytes remaining in the message.
         """
         b = self.packet.read(n)
-        max_pad_size = 1<<20  # Limit padding to 1 MB
-        if len(b) < n and n < max_pad_size:
-            return b + '\x00' * (n - len(b))
+        max_pad_size = 1 << 20  # Limit padding to 1 MB
+        if len(b) < n < max_pad_size:
+            return b + zero_byte * (n - len(b))
         return b
 
     def get_byte(self):
         """
-        Return the next byte of the Message, without decomposing it.  This
-        is equivalent to L{get_bytes(1)<get_bytes>}.
+        Return the next byte of the message, without decomposing it.  This
+        is equivalent to `get_bytes(1) <get_bytes>`.
 
-        @return: the next byte of the Message, or C{'\000'} if there aren't
+        :return:
+            the next (`str`) byte of the message, or ``'\000'`` if there aren't
             any bytes remaining.
-        @rtype: string
         """
         return self.get_bytes(1)
 
     def get_boolean(self):
         """
         Fetch a boolean from the stream.
-
-        @return: C{True} or C{False} (from the Message).
-        @rtype: bool
         """
         b = self.get_bytes(1)
-        return b != '\x00'
+        return b != zero_byte
 
     def get_int(self):
         """
         Fetch an int from the stream.
 
+        :return: a 32-bit unsigned `int`.
+        """
+        byte = self.get_bytes(1)
+        if byte == max_byte:
+            return util.inflate_long(self.get_binary())
+        byte += self.get_bytes(3)
+        return struct.unpack('>I', byte)[0]
+
+    def get_size(self):
+        """
+        Fetch an int from the stream.
+
         @return: a 32-bit unsigned integer.
         @rtype: int
         """
@@ -149,8 +154,7 @@ class Message (object):
         """
         Fetch a 64-bit int from the stream.
 
-        @return: a 64-bit unsigned integer.
-        @rtype: long
+        :return: a 64-bit unsigned integer (`long`).
         """
         return struct.unpack('>Q', self.get_bytes(8))[0]
 
@@ -158,13 +162,20 @@ class Message (object):
         """
         Fetch a long int (mpint) from the stream.
 
-        @return: an arbitrary-length integer.
-        @rtype: long
+        :return: an arbitrary-length integer (`long`).
         """
-        return util.inflate_long(self.get_string())
+        return util.inflate_long(self.get_binary())
 
     def get_string(self):
         """
+        Fetch a `str` from the stream.  This could be a byte string and may
+        contain unprintable characters.  (It's not unheard of for a string to
+        contain another byte-stream message.)
+        """
+        return self.get_bytes(self.get_size())
+
+    def get_text(self):
+        """
         Fetch a string from the stream.  This could be a byte string and may
         contain unprintable characters.  (It's not unheard of for a string to
         contain another byte-stream Message.)
@@ -172,24 +183,33 @@ class Message (object):
         @return: a string.
         @rtype: string
         """
-        return self.get_bytes(self.get_int())
+        return u(self.get_bytes(self.get_size()))
+        #return self.get_bytes(self.get_size())
 
-    def get_list(self):
+    def get_binary(self):
         """
-        Fetch a list of strings from the stream.  These are trivially encoded
-        as comma-separated values in a string.
+        Fetch a string from the stream.  This could be a byte string and may
+        contain unprintable characters.  (It's not unheard of for a string to
+        contain another byte-stream Message.)
 
-        @return: a list of strings.
-        @rtype: list of strings
+        @return: a string.
+        @rtype: string
         """
-        return self.get_string().split(',')
+        return self.get_bytes(self.get_size())
+
+    def get_list(self):
+        """
+        Fetch a `list` of `strings <str>` from the stream.
+        
+        These are trivially encoded as comma-separated values in a string.
+        """
+        return self.get_text().split(',')
 
     def add_bytes(self, b):
         """
         Write bytes to the stream, without any formatting.
         
-        @param b: bytes to add
-        @type b: str
+        :param str b: bytes to add
         """
         self.packet.write(b)
         return self
@@ -198,8 +218,7 @@ class Message (object):
         """
         Write a single byte to the stream, without any formatting.
         
-        @param b: byte to add
-        @type b: str
+        :param str b: byte to add
         """
         self.packet.write(b)
         return self
@@ -208,31 +227,41 @@ class Message (object):
         """
         Add a boolean value to the stream.
         
-        @param b: boolean value to add
-        @type b: bool
+        :param bool b: boolean value to add
         """
         if b:
-            self.add_byte('\x01')
+            self.packet.write(one_byte)
         else:
-            self.add_byte('\x00')
+            self.packet.write(zero_byte)
         return self
             
-    def add_int(self, n):
+    def add_size(self, n):
         """
         Add an integer to the stream.
         
-        @param n: integer to add
-        @type n: int
+        :param int n: integer to add
         """
         self.packet.write(struct.pack('>I', n))
         return self
+            
+    def add_int(self, n):
+        """
+        Add an integer to the stream.
+        
+        :param int n: integer to add
+        """
+        if n >= Message.big_int:
+            self.packet.write(max_byte)
+            self.add_string(util.deflate_long(n))
+        else:
+            self.packet.write(struct.pack('>I', n))
+        return self
 
     def add_int64(self, n):
         """
         Add a 64-bit int to the stream.
 
-        @param n: long int to add
-        @type n: long
+        :param long n: long int to add
         """
         self.packet.write(struct.pack('>Q', n))
         return self
@@ -242,8 +271,7 @@ class Message (object):
         Add a long int to the stream, encoded as an infinite-precision
         integer.  This method only works on positive numbers.
         
-        @param z: long int to add
-        @type z: long
+        :param long z: long int to add
         """
         self.add_string(util.deflate_long(z))
         return self
@@ -252,10 +280,10 @@ class Message (object):
         """
         Add a string to the stream.
         
-        @param s: string to add
-        @type s: str
+        :param str s: string to add
         """
-        self.add_int(len(s))
+        s = asbytes(s)
+        self.add_size(len(s))
         self.packet.write(s)
         return self
 
@@ -265,38 +293,30 @@ class Message (object):
         a single string of values separated by commas.  (Yes, really, that's
         how SSH2 does it.)
         
-        @param l: list of strings to add
-        @type l: list(str)
+        :param list l: list of strings to add
         """
         self.add_string(','.join(l))
         return self
         
     def _add(self, i):
-        if type(i) is str:
-            return self.add_string(i)
-        elif type(i) is int:
-            return self.add_int(i)
-        elif type(i) is long:
-            if i > 0xffffffffL:
-                return self.add_mpint(i)
-            else:
-                return self.add_int(i)
-        elif type(i) is bool:
+        if type(i) is bool:
             return self.add_boolean(i)
+        elif isinstance(i, integer_types):
+            return self.add_int(i)
         elif type(i) is list:
             return self.add_list(i)
         else:
-            raise Exception('Unknown type')
+            return self.add_string(i)
 
     def add(self, *seq):
         """
         Add a sequence of items to the stream.  The values are encoded based
         on their type: str, int, bool, list, or long.
+
+        .. warning::
+            Longs are encoded non-deterministically.  Don't use this method.
         
-        @param seq: the sequence of items
-        @type seq: sequence
-        
-        @bug: longs are encoded non-deterministically.  Don't use this method.
+        :param seq: the sequence of items
         """
         for item in seq:
             self._add(item)
diff --git a/paramiko/packet.py b/paramiko/packet.py
index 6ab7363..e97d92f 100644
--- a/paramiko/packet.py
+++ b/paramiko/packet.py
@@ -17,27 +17,25 @@
 # 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA.
 
 """
-Packetizer.
+Packet handling
 """
 
 import errno
-import select
+import os
 import socket
 import struct
 import threading
 import time
+from hmac import HMAC
 
-from paramiko.common import *
 from paramiko import util
+from paramiko.common import linefeed_byte, cr_byte_value, asbytes, MSG_NAMES, \
+    DEBUG, xffffffff, zero_byte
+from paramiko.py3compat import u, byte_ord
 from paramiko.ssh_exception import SSHException, ProxyCommandFailure
 from paramiko.message import Message
 
 
-try:
-    from r_hmac import HMAC
-except ImportError:
-    from Crypto.Hash.HMAC import HMAC
-
 def compute_hmac(key, message, digest_class):
     return HMAC(key, message, digest_class).digest()
 
@@ -56,8 +54,8 @@ class Packetizer (object):
     REKEY_PACKETS = pow(2, 29)
     REKEY_BYTES = pow(2, 29)
 
-    REKEY_PACKETS_OVERFLOW_MAX = pow(2,29)      # Allow receiving this many packets after a re-key request before terminating
-    REKEY_BYTES_OVERFLOW_MAX = pow(2,29)        # Allow receiving this many bytes after a re-key request before terminating
+    REKEY_PACKETS_OVERFLOW_MAX = pow(2, 29)     # Allow receiving this many packets after a re-key request before terminating
+    REKEY_BYTES_OVERFLOW_MAX = pow(2, 29)       # Allow receiving this many bytes after a re-key request before terminating
 
     def __init__(self, socket):
         self.__socket = socket
@@ -66,7 +64,7 @@ class Packetizer (object):
         self.__dump_packets = False
         self.__need_rekey = False
         self.__init_count = 0
-        self.__remainder = ''
+        self.__remainder = bytes()
 
         # used for noticing when to re-key:
         self.__sent_bytes = 0
@@ -86,12 +84,12 @@ class Packetizer (object):
         self.__sdctr_out = False
         self.__mac_engine_out = None
         self.__mac_engine_in = None
-        self.__mac_key_out = ''
-        self.__mac_key_in = ''
+        self.__mac_key_out = bytes()
+        self.__mac_key_in = bytes()
         self.__compress_engine_out = None
         self.__compress_engine_in = None
-        self.__sequence_number_out = 0L
-        self.__sequence_number_in = 0L
+        self.__sequence_number_out = 0
+        self.__sequence_number_in = 0
 
         # lock around outbound writes (packet computation)
         self.__write_lock = threading.RLock()
@@ -103,7 +101,7 @@ class Packetizer (object):
 
     def set_log(self, log):
         """
-        Set the python log object to use for logging.
+        Set the Python log object to use for logging.
         """
         self.__logger = log
 
@@ -152,6 +150,7 @@ class Packetizer (object):
 
     def close(self):
         self.__closed = True
+        self.__socket.close()
 
     def set_hexdump(self, hexdump):
         self.__dump_packets = hexdump
@@ -167,17 +166,15 @@ class Packetizer (object):
 
     def need_rekey(self):
         """
-        Returns C{True} if a new set of keys needs to be negotiated.  This
+        Returns ``True`` if a new set of keys needs to be negotiated.  This
         will be triggered during a packet read or write, so it should be
         checked after every read or write, or at least after every few.
-
-        @return: C{True} if a new set of keys needs to be negotiated
         """
         return self.__need_rekey
 
     def set_keepalive(self, interval, callback):
         """
-        Turn on/off the callback keepalive.  If C{interval} seconds pass with
+        Turn on/off the callback keepalive.  If ``interval`` seconds pass with
         no data read from or written to the socket, the callback will be
         executed and the timer will be reset.
         """
@@ -189,21 +186,18 @@ class Packetizer (object):
         """
         Read as close to N bytes as possible, blocking as long as necessary.
 
-        @param n: number of bytes to read
-        @type n: int
-        @return: the data read
-        @rtype: str
-        @raise EOFError: if the socket was closed before all the bytes could
-            be read
+        :param int n: number of bytes to read
+        :return: the data read, as a `str`
+
+        :raises EOFError:
+            if the socket was closed before all the bytes could be read
         """
-        out = ''
+        out = bytes()
         # handle over-reading from reading the banner line
         if len(self.__remainder) > 0:
             out = self.__remainder[:n]
             self.__remainder = self.__remainder[n:]
             n -= len(out)
-        if PY22:
-            return self._py22_read_all(n, out)
         while n > 0:
             got_timeout = False
             try:
@@ -214,7 +208,7 @@ class Packetizer (object):
                 n -= len(x)
             except socket.timeout:
                 got_timeout = True
-            except socket.error, e:
+            except socket.error as e:
                 # on Linux, sometimes instead of socket.timeout, we get
                 # EAGAIN.  this is a bug in recent (> 2.6.9) kernels but
                 # we need to work around it.
@@ -243,7 +237,7 @@ class Packetizer (object):
                 n = self.__socket.send(out)
             except socket.timeout:
                 retry_write = True
-            except socket.error, e:
+            except socket.error as e:
                 if (type(e.args) is tuple) and (len(e.args) > 0) and (e.args[0] == errno.EAGAIN):
                     retry_write = True
                 elif (type(e.args) is tuple) and (len(e.args) > 0) and (e.args[0] == errno.EINTR):
@@ -252,7 +246,7 @@ class Packetizer (object):
                 else:
                     n = -1
             except ProxyCommandFailure:
-                raise # so it doesn't get swallowed by the below catchall
+                raise  # so it doesn't get swallowed by the below catchall
             except Exception:
                 # could be: (32, 'Broken pipe')
                 n = -1
@@ -273,22 +267,22 @@ class Packetizer (object):
         line, so it's okay to attempt large reads.
         """
         buf = self.__remainder
-        while not '\n' in buf:
+        while not linefeed_byte in buf:
             buf += self._read_timeout(timeout)
-        n = buf.index('\n')
-        self.__remainder = buf[n+1:]
+        n = buf.index(linefeed_byte)
+        self.__remainder = buf[n + 1:]
         buf = buf[:n]
-        if (len(buf) > 0) and (buf[-1] == '\r'):
+        if (len(buf) > 0) and (buf[-1] == cr_byte_value):
             buf = buf[:-1]
-        return buf
+        return u(buf)
 
     def send_message(self, data):
         """
         Write a block of data using the current cipher, as an SSH block.
         """
         # encrypt this sucka
-        data = str(data)
-        cmd = ord(data[0])
+        data = asbytes(data)
+        cmd = byte_ord(data[0])
         if cmd in MSG_NAMES:
             cmd_name = MSG_NAMES[cmd]
         else:
@@ -302,21 +296,21 @@ class Packetizer (object):
             if self.__dump_packets:
                 self._log(DEBUG, 'Write packet <%s>, length %d' % (cmd_name, orig_len))
                 self._log(DEBUG, util.format_binary(packet, 'OUT: '))
-            if self.__block_engine_out != None:
+            if self.__block_engine_out is not None:
                 out = self.__block_engine_out.encrypt(packet)
             else:
                 out = packet
             # + mac
-            if self.__block_engine_out != None:
+            if self.__block_engine_out is not None:
                 payload = struct.pack('>I', self.__sequence_number_out) + packet
                 out += compute_hmac(self.__mac_key_out, payload, self.__mac_engine_out)[:self.__mac_size_out]
-            self.__sequence_number_out = (self.__sequence_number_out + 1) & 0xffffffffL
+            self.__sequence_number_out = (self.__sequence_number_out + 1) & xffffffff
             self.write_all(out)
 
             self.__sent_bytes += len(out)
             self.__sent_packets += 1
-            if ((self.__sent_packets >= self.REKEY_PACKETS) or (self.__sent_bytes >= self.REKEY_BYTES)) \
-                   and not self.__need_rekey:
+            if (self.__sent_packets >= self.REKEY_PACKETS or self.__sent_bytes >= self.REKEY_BYTES)\
+                    and not self.__need_rekey:
                 # only ask once for rekeying
                 self._log(DEBUG, 'Rekeying (hit %d packets, %d bytes sent)' %
                           (self.__sent_packets, self.__sent_bytes))
@@ -331,14 +325,14 @@ class Packetizer (object):
         Only one thread should ever be in this function (no other locking is
         done).
 
-        @raise SSHException: if the packet is mangled
-        @raise NeedRekeyException: if the transport should rekey
+        :raises SSHException: if the packet is mangled
+        :raises NeedRekeyException: if the transport should rekey
         """
         header = self.read_all(self.__block_size_in, check_rekey=True)
-        if self.__block_engine_in != None:
+        if self.__block_engine_in is not None:
             header = self.__block_engine_in.decrypt(header)
         if self.__dump_packets:
-            self._log(DEBUG, util.format_binary(header, 'IN: '));
+            self._log(DEBUG, util.format_binary(header, 'IN: '))
         packet_size = struct.unpack('>I', header[:4])[0]
         # leftover contains decrypted bytes from the first block (after the length field)
         leftover = header[4:]
@@ -347,21 +341,21 @@ class Packetizer (object):
         buf = self.read_all(packet_size + self.__mac_size_in - len(leftover))
         packet = buf[:packet_size - len(leftover)]
         post_packet = buf[packet_size - len(leftover):]
-        if self.__block_engine_in != None:
+        if self.__block_engine_in is not None:
             packet = self.__block_engine_in.decrypt(packet)
         if self.__dump_packets:
-            self._log(DEBUG, util.format_binary(packet, 'IN: '));
+            self._log(DEBUG, util.format_binary(packet, 'IN: '))
         packet = leftover + packet
 
         if self.__mac_size_in > 0:
             mac = post_packet[:self.__mac_size_in]
             mac_payload = struct.pack('>II', self.__sequence_number_in, packet_size) + packet
             my_mac = compute_hmac(self.__mac_key_in, mac_payload, self.__mac_engine_in)[:self.__mac_size_in]
-            if my_mac != mac:
+            if not util.constant_time_bytes_eq(my_mac, mac):
                 raise SSHException('Mismatched MAC')
-        padding = ord(packet[0])
+        padding = byte_ord(packet[0])
         payload = packet[1:packet_size - padding]
-        
+
         if self.__dump_packets:
             self._log(DEBUG, 'Got payload (%d bytes, %d padding)' % (packet_size, padding))
 
@@ -370,7 +364,7 @@ class Packetizer (object):
 
         msg = Message(payload[1:])
         msg.seqno = self.__sequence_number_in
-        self.__sequence_number_in = (self.__sequence_number_in + 1) & 0xffffffffL
+        self.__sequence_number_in = (self.__sequence_number_in + 1) & xffffffff
 
         # check for rekey
         raw_packet_size = packet_size + self.__mac_size_in + 4
@@ -393,7 +387,7 @@ class Packetizer (object):
             self.__received_packets_overflow = 0
             self._trigger_rekey()
 
-        cmd = ord(payload[0])
+        cmd = byte_ord(payload[0])
         if cmd in MSG_NAMES:
             cmd_name = MSG_NAMES[cmd]
         else:
@@ -402,10 +396,8 @@ class Packetizer (object):
             self._log(DEBUG, 'Read packet <%s>, length %d' % (cmd_name, len(payload)))
         return cmd, msg
 
-
     ##########  protected
 
-
     def _log(self, level, msg):
         if self.__logger is None:
             return
@@ -417,7 +409,7 @@ class Packetizer (object):
 
     def _check_keepalive(self):
         if (not self.__keepalive_interval) or (not self.__block_engine_out) or \
-            self.__need_rekey:
+                self.__need_rekey:
             # wait till we're encrypting, and not in the middle of rekeying
             return
         now = time.time()
@@ -425,40 +417,7 @@ class Packetizer (object):
             self.__keepalive_callback()
             self.__keepalive_last = now
 
-    def _py22_read_all(self, n, out):
-        while n > 0:
-            r, w, e = select.select([self.__socket], [], [], 0.1)
-            if self.__socket not in r:
-                if self.__closed:
-                    raise EOFError()
-                self._check_keepalive()
-            else:
-                x = self.__socket.recv(n)
-                if len(x) == 0:
-                    raise EOFError()
-                out += x
-                n -= len(x)
-        return out
-
-    def _py22_read_timeout(self, timeout):
-        start = time.time()
-        while True:
-            r, w, e = select.select([self.__socket], [], [], 0.1)
-            if self.__socket in r:
-                x = self.__socket.recv(1)
-                if len(x) == 0:
-                    raise EOFError()
-                break
-            if self.__closed:
-                raise EOFError()
-            now = time.time()
-            if now - start >= timeout:
-                raise socket.timeout()
-        return x
-
     def _read_timeout(self, timeout):
-        if PY22:
-            return self._py22_read_timeout(timeout)
         start = time.time()
         while True:
             try:
@@ -468,9 +427,9 @@ class Packetizer (object):
                 break
             except socket.timeout:
                 pass
-            except EnvironmentError, e:
-                if ((type(e.args) is tuple) and (len(e.args) > 0) and
-                    (e.args[0] == errno.EINTR)):
+            except EnvironmentError as e:
+                if (type(e.args) is tuple and len(e.args) > 0 and
+                        e.args[0] == errno.EINTR):
                     pass
                 else:
                     raise
@@ -490,9 +449,9 @@ class Packetizer (object):
         if self.__sdctr_out or self.__block_engine_out is None:
             # cute trick i caught openssh doing: if we're not encrypting or SDCTR mode (RFC4344),
             # don't waste random bytes for the padding
-            packet += (chr(0) * padding)
+            packet += (zero_byte * padding)
         else:
-            packet += rng.read(padding)
+            packet += os.urandom(padding)
         return packet
 
     def _trigger_rekey(self):
diff --git a/paramiko/pipe.py b/paramiko/pipe.py
index db43d54..b0cfcf2 100644
--- a/paramiko/pipe.py
+++ b/paramiko/pipe.py
@@ -17,11 +17,12 @@
 # 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA.
 
 """
-Abstraction of a one-way pipe where the read end can be used in select().
-Normally this is trivial, but Windows makes it nearly impossible.
+Abstraction of a one-way pipe where the read end can be used in
+`select.select`. Normally this is trivial, but Windows makes it nearly
+impossible.
 
 The pipe acts like an Event, which can be set or cleared. When set, the pipe
-will trigger as readable in select().
+will trigger as readable in `select <select.select>`.
 """
 
 import sys
@@ -29,7 +30,7 @@ import os
 import socket
 
 
-def make_pipe ():
+def make_pipe():
     if sys.platform[:3] != 'win':
         p = PosixPipe()
     else:
@@ -38,34 +39,34 @@ def make_pipe ():
 
 
 class PosixPipe (object):
-    def __init__ (self):
+    def __init__(self):
         self._rfd, self._wfd = os.pipe()
         self._set = False
         self._forever = False
         self._closed = False
     
-    def close (self):
+    def close(self):
         os.close(self._rfd)
         os.close(self._wfd)
         # used for unit tests:
         self._closed = True
     
-    def fileno (self):
+    def fileno(self):
         return self._rfd
 
-    def clear (self):
+    def clear(self):
         if not self._set or self._forever:
             return
         os.read(self._rfd, 1)
         self._set = False
     
-    def set (self):
+    def set(self):
         if self._set or self._closed:
             return
         self._set = True
-        os.write(self._wfd, '*')
+        os.write(self._wfd, b'*')
     
-    def set_forever (self):
+    def set_forever(self):
         self._forever = True
         self.set()
 
@@ -75,7 +76,7 @@ class WindowsPipe (object):
     On Windows, only an OS-level "WinSock" may be used in select(), but reads
     and writes must be to the actual socket object.
     """
-    def __init__ (self):
+    def __init__(self):
         serv = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
         serv.bind(('127.0.0.1', 0))
         serv.listen(1)
@@ -90,13 +91,13 @@ class WindowsPipe (object):
         self._forever = False
         self._closed = False
     
-    def close (self):
+    def close(self):
         self._rsock.close()
         self._wsock.close()
         # used for unit tests:
         self._closed = True
     
-    def fileno (self):
+    def fileno(self):
         return self._rsock.fileno()
 
     def clear (self):
@@ -109,7 +110,7 @@ class WindowsPipe (object):
         if self._set or self._closed:
             return
         self._set = True
-        self._wsock.send('*')
+        self._wsock.send(b'*')
 
     def set_forever (self):
         self._forever = True
diff --git a/paramiko/pkey.py b/paramiko/pkey.py
index b1199df..373563f 100644
--- a/paramiko/pkey.py
+++ b/paramiko/pkey.py
@@ -23,13 +23,13 @@ Common API for all public keys.
 import base64
 from binascii import hexlify, unhexlify
 import os
+from hashlib import md5
 
-from Crypto.Hash import MD5
 from Crypto.Cipher import DES3, AES
 
-from paramiko.common import *
 from paramiko import util
-from paramiko.message import Message
+from paramiko.common import o600, zero_byte
+from paramiko.py3compat import u, encodebytes, decodebytes, b
 from paramiko.ssh_exception import SSHException, PasswordRequiredException
 
 
@@ -40,40 +40,39 @@ class PKey (object):
 
     # known encryption types for private key files:
     _CIPHER_TABLE = {
-        'AES-128-CBC': { 'cipher': AES, 'keysize': 16, 'blocksize': 16, 'mode': AES.MODE_CBC },
-        'DES-EDE3-CBC': { 'cipher': DES3, 'keysize': 24, 'blocksize': 8, 'mode': DES3.MODE_CBC },
+        'AES-128-CBC': {'cipher': AES, 'keysize': 16, 'blocksize': 16, 'mode': AES.MODE_CBC},
+        'DES-EDE3-CBC': {'cipher': DES3, 'keysize': 24, 'blocksize': 8, 'mode': DES3.MODE_CBC},
     }
 
-
     def __init__(self, msg=None, data=None):
         """
-        Create a new instance of this public key type.  If C{msg} is given,
+        Create a new instance of this public key type.  If ``msg`` is given,
         the key's public part(s) will be filled in from the message.  If
-        C{data} is given, the key's public part(s) will be filled in from
+        ``data`` is given, the key's public part(s) will be filled in from
         the string.
 
-        @param msg: an optional SSH L{Message} containing a public key of this
-        type.
-        @type msg: L{Message}
-        @param data: an optional string containing a public key of this type
-        @type data: str
+        :param .Message msg:
+            an optional SSH `.Message` containing a public key of this type.
+        :param str data: an optional string containing a public key of this type
 
-        @raise SSHException: if a key cannot be created from the C{data} or
-        C{msg} given, or no key was passed in.
+        :raises SSHException:
+            if a key cannot be created from the ``data`` or ``msg`` given, or
+            no key was passed in.
         """
         pass
 
-    def __str__(self):
+    def asbytes(self):
         """
-        Return a string of an SSH L{Message} made up of the public part(s) of
-        this key.  This string is suitable for passing to L{__init__} to
+        Return a string of an SSH `.Message` made up of the public part(s) of
+        this key.  This string is suitable for passing to `__init__` to
         re-create the key object later.
-
-        @return: string representation of an SSH key message.
-        @rtype: str
         """
-        return ''
+        return bytes()
 
+    def __str__(self):
+        return self.asbytes()
+
+    # noinspection PyUnresolvedReferences
     def __cmp__(self, other):
         """
         Compare this key to another.  Returns 0 if this key is equivalent to
@@ -81,24 +80,24 @@ class PKey (object):
         of the key are compared, so a public key will compare equal to its
         corresponding private key.
 
-        @param other: key to compare to.
-        @type other: L{PKey}
-        @return: 0 if the two keys are equivalent, non-0 otherwise.
-        @rtype: int
+        :param .Pkey other: key to compare to.
         """
         hs = hash(self)
         ho = hash(other)
         if hs != ho:
             return cmp(hs, ho)
-        return cmp(str(self), str(other))
+        return cmp(self.asbytes(), other.asbytes())
+
+    def __eq__(self, other):
+        return hash(self) == hash(other)
 
     def get_name(self):
         """
         Return the name of this private key implementation.
 
-        @return: name of this private key type, in SSH terminology (for
-        example, C{"ssh-rsa"}).
-        @rtype: str
+        :return:
+            name of this private key type, in SSH terminology, as a `str` (for
+            example, ``"ssh-rsa"``).
         """
         return ''
 
@@ -107,18 +106,14 @@ class PKey (object):
         Return the number of significant bits in this key.  This is useful
         for judging the relative security of a key.
 
-        @return: bits in the key.
-        @rtype: int
+        :return: bits in the key (as an `int`)
         """
         return 0
 
     def can_sign(self):
         """
-        Return C{True} if this key has the private part necessary for signing
+        Return ``True`` if this key has the private part necessary for signing
         data.
-
-        @return: C{True} if this is a private key.
-        @rtype: bool
         """
         return False
 
@@ -127,11 +122,11 @@ class PKey (object):
         Return an MD5 fingerprint of the public part of this key.  Nothing
         secret is revealed.
 
-        @return: a 16-byte string (binary) of the MD5 fingerprint, in SSH
+        :return:
+            a 16-byte `string <str>` (binary) of the MD5 fingerprint, in SSH
             format.
-        @rtype: str
         """
-        return MD5.new(str(self)).digest()
+        return md5(self.asbytes()).digest()
 
     def get_base64(self):
         """
@@ -139,61 +134,50 @@ class PKey (object):
         secret is revealed.  This format is compatible with that used to store
         public key files or recognized host keys.
 
-        @return: a base64 string containing the public part of the key.
-        @rtype: str
+        :return: a base64 `string <str>` containing the public part of the key.
         """
-        return base64.encodestring(str(self)).replace('\n', '')
+        return u(encodebytes(self.asbytes())).replace('\n', '')
 
-    def sign_ssh_data(self, rng, data):
+    def sign_ssh_data(self, data):
         """
-        Sign a blob of data with this private key, and return a L{Message}
+        Sign a blob of data with this private key, and return a `.Message`
         representing an SSH signature message.
 
-        @param rng: a secure random number generator.
-        @type rng: L{Crypto.Util.rng.RandomPool}
-        @param data: the data to sign.
-        @type data: str
-        @return: an SSH signature message.
-        @rtype: L{Message}
+        :param str data: the data to sign.
+        :return: an SSH signature `message <.Message>`.
         """
-        return ''
+        return bytes()
 
     def verify_ssh_sig(self, data, msg):
         """
         Given a blob of data, and an SSH message representing a signature of
         that data, verify that it was signed with this key.
 
-        @param data: the data that was signed.
-        @type data: str
-        @param msg: an SSH signature message
-        @type msg: L{Message}
-        @return: C{True} if the signature verifies correctly; C{False}
-            otherwise.
-        @rtype: boolean
+        :param str data: the data that was signed.
+        :param .Message msg: an SSH signature message
+        :return:
+            ``True`` if the signature verifies correctly; ``False`` otherwise.
         """
         return False
 
     def from_private_key_file(cls, filename, password=None):
         """
         Create a key object by reading a private key file.  If the private
-        key is encrypted and C{password} is not C{None}, the given password
-        will be used to decrypt the key (otherwise L{PasswordRequiredException}
-        is thrown).  Through the magic of python, this factory method will
-        exist in all subclasses of PKey (such as L{RSAKey} or L{DSSKey}), but
+        key is encrypted and ``password`` is not ``None``, the given password
+        will be used to decrypt the key (otherwise `.PasswordRequiredException`
+        is thrown).  Through the magic of Python, this factory method will
+        exist in all subclasses of PKey (such as `.RSAKey` or `.DSSKey`), but
         is useless on the abstract PKey class.
 
-        @param filename: name of the file to read
-        @type filename: str
-        @param password: an optional password to use to decrypt the key file,
+        :param str filename: name of the file to read
+        :param str password: an optional password to use to decrypt the key file,
             if it's encrypted
-        @type password: str
-        @return: a new key object based on the given private key
-        @rtype: L{PKey}
+        :return: a new `.PKey` based on the given private key
 
-        @raise IOError: if there was an error reading the file
-        @raise PasswordRequiredException: if the private key file is
-            encrypted, and C{password} is C{None}
-        @raise SSHException: if the key file is invalid
+        :raises IOError: if there was an error reading the file
+        :raises PasswordRequiredException: if the private key file is
+            encrypted, and ``password`` is ``None``
+        :raises SSHException: if the key file is invalid
         """
         key = cls(filename=filename, password=password)
         return key
@@ -202,22 +186,19 @@ class PKey (object):
     def from_private_key(cls, file_obj, password=None):
         """
         Create a key object by reading a private key from a file (or file-like)
-        object.  If the private key is encrypted and C{password} is not C{None},
+        object.  If the private key is encrypted and ``password`` is not ``None``,
         the given password will be used to decrypt the key (otherwise
-        L{PasswordRequiredException} is thrown).
+        `.PasswordRequiredException` is thrown).
 
-        @param file_obj: the file to read from
-        @type file_obj: file
-        @param password: an optional password to use to decrypt the key, if it's
-            encrypted
-        @type password: str
-        @return: a new key object based on the given private key
-        @rtype: L{PKey}
+        :param file file_obj: the file to read from
+        :param str password:
+            an optional password to use to decrypt the key, if it's encrypted
+        :return: a new `.PKey` based on the given private key
 
-        @raise IOError: if there was an error reading the key
-        @raise PasswordRequiredException: if the private key file is encrypted,
-            and C{password} is C{None}
-        @raise SSHException: if the key file is invalid
+        :raises IOError: if there was an error reading the key
+        :raises PasswordRequiredException: if the private key file is encrypted,
+            and ``password`` is ``None``
+        :raises SSHException: if the key file is invalid
         """
         key = cls(file_obj=file_obj, password=password)
         return key
@@ -226,59 +207,52 @@ class PKey (object):
     def write_private_key_file(self, filename, password=None):
         """
         Write private key contents into a file.  If the password is not
-        C{None}, the key is encrypted before writing.
+        ``None``, the key is encrypted before writing.
 
-        @param filename: name of the file to write
-        @type filename: str
-        @param password: an optional password to use to encrypt the key file
-        @type password: str
+        :param str filename: name of the file to write
+        :param str password:
+            an optional password to use to encrypt the key file
 
-        @raise IOError: if there was an error writing the file
-        @raise SSHException: if the key is invalid
+        :raises IOError: if there was an error writing the file
+        :raises SSHException: if the key is invalid
         """
         raise Exception('Not implemented in PKey')
 
     def write_private_key(self, file_obj, password=None):
         """
         Write private key contents into a file (or file-like) object.  If the
-        password is not C{None}, the key is encrypted before writing.
+        password is not ``None``, the key is encrypted before writing.
 
-        @param file_obj: the file object to write into
-        @type file_obj: file
-        @param password: an optional password to use to encrypt the key
-        @type password: str
+        :param file file_obj: the file object to write into
+        :param str password: an optional password to use to encrypt the key
 
-        @raise IOError: if there was an error writing to the file
-        @raise SSHException: if the key is invalid
+        :raises IOError: if there was an error writing to the file
+        :raises SSHException: if the key is invalid
         """
         raise Exception('Not implemented in PKey')
 
     def _read_private_key_file(self, tag, filename, password=None):
         """
         Read an SSH2-format private key file, looking for a string of the type
-        C{"BEGIN xxx PRIVATE KEY"} for some C{xxx}, base64-decode the text we
+        ``"BEGIN xxx PRIVATE KEY"`` for some ``xxx``, base64-decode the text we
         find, and return it as a string.  If the private key is encrypted and
-        C{password} is not C{None}, the given password will be used to decrypt
-        the key (otherwise L{PasswordRequiredException} is thrown).
-
-        @param tag: C{"RSA"} or C{"DSA"}, the tag used to mark the data block.
-        @type tag: str
-        @param filename: name of the file to read.
-        @type filename: str
-        @param password: an optional password to use to decrypt the key file,
-            if it's encrypted.
-        @type password: str
-        @return: data blob that makes up the private key.
-        @rtype: str
-
-        @raise IOError: if there was an error reading the file.
-        @raise PasswordRequiredException: if the private key file is
-            encrypted, and C{password} is C{None}.
-        @raise SSHException: if the key file is invalid.
-        """
-        f = open(filename, 'r')
-        data = self._read_private_key(tag, f, password)
-        f.close()
+        ``password`` is not ``None``, the given password will be used to decrypt
+        the key (otherwise `.PasswordRequiredException` is thrown).
+
+        :param str tag: ``"RSA"`` or ``"DSA"``, the tag used to mark the data block.
+        :param str filename: name of the file to read.
+        :param str password:
+            an optional password to use to decrypt the key file, if it's
+            encrypted.
+        :return: data blob (`str`) that makes up the private key.
+
+        :raises IOError: if there was an error reading the file.
+        :raises PasswordRequiredException: if the private key file is
+            encrypted, and ``password`` is ``None``.
+        :raises SSHException: if the key file is invalid.
+        """
+        with open(filename, 'r') as f:
+            data = self._read_private_key(tag, f, password)
         return data
 
     def _read_private_key(self, tag, f, password=None):
@@ -303,8 +277,8 @@ class PKey (object):
             end += 1
         # if we trudged to the end of the file, just try to cope.
         try:
-            data = base64.decodestring(''.join(lines[start:end]))
-        except base64.binascii.Error, e:
+            data = decodebytes(b(''.join(lines[start:end])))
+        except base64.binascii.Error as e:
             raise SSHException('base64 decoding error: ' + str(e))
         if 'proc-type' not in headers:
             # unencryped: done
@@ -315,7 +289,7 @@ class PKey (object):
         try:
             encryption_type, saltstr = headers['dek-info'].split(',')
         except:
-            raise SSHException('Can\'t parse DEK-info in private key file')
+            raise SSHException("Can't parse DEK-info in private key file")
         if encryption_type not in self._CIPHER_TABLE:
             raise SSHException('Unknown private key cipher "%s"' % encryption_type)
         # if no password was passed in, raise an exception pointing out that we need one
@@ -324,8 +298,8 @@ class PKey (object):
         cipher = self._CIPHER_TABLE[encryption_type]['cipher']
         keysize = self._CIPHER_TABLE[encryption_type]['keysize']
         mode = self._CIPHER_TABLE[encryption_type]['mode']
-        salt = unhexlify(saltstr)
-        key = util.generate_key_bytes(MD5, salt, password, keysize)
+        salt = unhexlify(b(saltstr))
+        key = util.generate_key_bytes(md5, salt, password, keysize)
         return cipher.new(key, mode, salt).decrypt(data)
 
     def _write_private_key_file(self, tag, filename, data, password=None):
@@ -335,47 +309,42 @@ class PKey (object):
         a trivially-encoded format (base64) which is completely insecure.  If
         a password is given, DES-EDE3-CBC is used.
 
-        @param tag: C{"RSA"} or C{"DSA"}, the tag used to mark the data block.
-        @type tag: str
-        @param filename: name of the file to write.
-        @type filename: str
-        @param data: data blob that makes up the private key.
-        @type data: str
-        @param password: an optional password to use to encrypt the file.
-        @type password: str
+        :param str tag: ``"RSA"`` or ``"DSA"``, the tag used to mark the data block.
+        :param file filename: name of the file to write.
+        :param str data: data blob that makes up the private key.
+        :param str password: an optional password to use to encrypt the file.
 
-        @raise IOError: if there was an error writing the file.
+        :raises IOError: if there was an error writing the file.
         """
-        f = open(filename, 'w', 0600)
-        # grrr... the mode doesn't always take hold
-        os.chmod(filename, 0600)
-        self._write_private_key(tag, f, data, password)
-        f.close()
+        with open(filename, 'w', o600) as f:
+            # grrr... the mode doesn't always take hold
+            os.chmod(filename, o600)
+            self._write_private_key(tag, f, data, password)
 
     def _write_private_key(self, tag, f, data, password=None):
         f.write('-----BEGIN %s PRIVATE KEY-----\n' % tag)
         if password is not None:
             # since we only support one cipher here, use it
-            cipher_name = self._CIPHER_TABLE.keys()[0]
+            cipher_name = list(self._CIPHER_TABLE.keys())[0]
             cipher = self._CIPHER_TABLE[cipher_name]['cipher']
             keysize = self._CIPHER_TABLE[cipher_name]['keysize']
             blocksize = self._CIPHER_TABLE[cipher_name]['blocksize']
             mode = self._CIPHER_TABLE[cipher_name]['mode']
-            salt = rng.read(8)
-            key = util.generate_key_bytes(MD5, salt, password, keysize)
+            salt = os.urandom(16)
+            key = util.generate_key_bytes(md5, salt, password, keysize)
             if len(data) % blocksize != 0:
                 n = blocksize - len(data) % blocksize
-                #data += rng.read(n)
+                #data += os.urandom(n)
                 # that would make more sense ^, but it confuses openssh.
-                data += '\0' * n
+                data += zero_byte * n
             data = cipher.new(key, mode, salt).encrypt(data)
             f.write('Proc-Type: 4,ENCRYPTED\n')
-            f.write('DEK-Info: %s,%s\n' % (cipher_name, hexlify(salt).upper()))
+            f.write('DEK-Info: %s,%s\n' % (cipher_name, u(hexlify(salt)).upper()))
             f.write('\n')
-        s = base64.encodestring(data)
+        s = u(encodebytes(data))
         # re-wrap to 64-char lines
         s = ''.join(s.split('\n'))
-        s = '\n'.join([s[i : i+64] for i in range(0, len(s), 64)])
+        s = '\n'.join([s[i: i + 64] for i in range(0, len(s), 64)])
         f.write(s)
         f.write('\n')
         f.write('-----END %s PRIVATE KEY-----\n' % tag)
diff --git a/paramiko/primes.py b/paramiko/primes.py
index 9419cd6..8e02e80 100644
--- a/paramiko/primes.py
+++ b/paramiko/primes.py
@@ -20,33 +20,17 @@
 Utility functions for dealing with primes.
 """
 
-from Crypto.Util import number
+import os
 
 from paramiko import util
+from paramiko.py3compat import byte_mask, long
 from paramiko.ssh_exception import SSHException
 
 
-def _generate_prime(bits, rng):
-    "primtive attempt at prime generation"
-    hbyte_mask = pow(2, bits % 8) - 1
-    while True:
-        # loop catches the case where we increment n into a higher bit-range
-        x = rng.read((bits+7) // 8)
-        if hbyte_mask > 0:
-            x = chr(ord(x[0]) & hbyte_mask) + x[1:]
-        n = util.inflate_long(x, 1)
-        n |= 1
-        n |= (1 << (bits - 1))
-        while not number.isPrime(n):
-            n += 2
-        if util.bit_length(n) == bits:
-            break
-    return n
-
-def _roll_random(rng, n):
-    "returns a random # from 0 to N-1"
-    bits = util.bit_length(n-1)
-    bytes = (bits + 7) // 8
+def _roll_random(n):
+    """returns a random # from 0 to N-1"""
+    bits = util.bit_length(n - 1)
+    byte_count = (bits + 7) // 8
     hbyte_mask = pow(2, bits % 8) - 1
 
     # so here's the plan:
@@ -56,9 +40,9 @@ def _roll_random(rng, n):
     # fits, so i can't guarantee that this loop will ever finish, but the odds
     # of it looping forever should be infinitesimal.
     while True:
-        x = rng.read(bytes)
+        x = os.urandom(byte_count)
         if hbyte_mask > 0:
-            x = chr(ord(x[0]) & hbyte_mask) + x[1:]
+            x = byte_mask(x[0], hbyte_mask) + x[1:]
         num = util.inflate_long(x, 1)
         if num < n:
             break
@@ -71,11 +55,10 @@ class ModulusPack (object):
     on systems that have such a file.
     """
 
-    def __init__(self, rpool):
+    def __init__(self):
         # pack is a hash of: bits -> [ (generator, modulus) ... ]
         self.pack = {}
         self.discarded = []
-        self.rng = rpool
 
     def _parse_modulus(self, line):
         timestamp, mod_type, tests, tries, size, generator, modulus = line.split()
@@ -109,29 +92,27 @@ class ModulusPack (object):
 
     def read_file(self, filename):
         """
-        @raise IOError: passed from any file operations that fail.
+        :raises IOError: passed from any file operations that fail.
         """
         self.pack = {}
-        f = open(filename, 'r')
-        for line in f:
-            line = line.strip()
-            if (len(line) == 0) or (line[0] == '#'):
-                continue
-            try:
-                self._parse_modulus(line)
-            except:
-                continue
-        f.close()
+        with open(filename, 'r') as f:
+            for line in f:
+                line = line.strip()
+                if (len(line) == 0) or (line[0] == '#'):
+                    continue
+                try:
+                    self._parse_modulus(line)
+                except:
+                    continue
 
     def get_modulus(self, min, prefer, max):
-        bitsizes = self.pack.keys()
-        bitsizes.sort()
+        bitsizes = sorted(self.pack.keys())
         if len(bitsizes) == 0:
             raise SSHException('no moduli available')
         good = -1
         # find nearest bitsize >= preferred
         for b in bitsizes:
-            if (b >= prefer) and (b < max) and ((b < good) or (good == -1)):
+            if (b >= prefer) and (b < max) and (b < good or good == -1):
                 good = b
         # if that failed, find greatest bitsize >= min
         if good == -1:
@@ -147,5 +128,5 @@ class ModulusPack (object):
             if min > good:
                 good = bitsizes[-1]
         # now pick a random modulus of this bitsize
-        n = _roll_random(self.rng, len(self.pack[good]))
+        n = _roll_random(len(self.pack[good]))
         return self.pack[good][n]
diff --git a/paramiko/proxy.py b/paramiko/proxy.py
index 3f5c8bb..8959b24 100644
--- a/paramiko/proxy.py
+++ b/paramiko/proxy.py
@@ -16,9 +16,6 @@
 # along with Paramiko; if not, write to the Free Software Foundation, Inc.,
 # 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA.
 
-"""
-L{ProxyCommand}.
-"""
 
 from datetime import datetime
 import os
@@ -36,18 +33,17 @@ class ProxyCommand(object):
     Wraps a subprocess running ProxyCommand-driven programs.
 
     This class implements a the socket-like interface needed by the
-    L{Transport} and L{Packetizer} classes. Using this class instead of a
+    `.Transport` and `.Packetizer` classes. Using this class instead of a
     regular socket makes it possible to talk with a Popen'd command that will
     proxy traffic between the client and a server hosted in another machine.
     """
     def __init__(self, command_line):
         """
         Create a new CommandProxy instance. The instance created by this
-        class can be passed as an argument to the L{Transport} class.
+        class can be passed as an argument to the `.Transport` class.
 
-        @param command_line: the command that should be executed and
-            used as the proxy.
-        @type command_line: str
+        :param str command_line:
+            the command that should be executed and used as the proxy.
         """
         self.cmd = shlsplit(command_line)
         self.process = Popen(self.cmd, stdin=PIPE, stdout=PIPE, stderr=PIPE)
@@ -59,12 +55,11 @@ class ProxyCommand(object):
         Write the content received from the SSH client to the standard
         input of the forked command.
 
-        @param content: string to be sent to the forked command
-        @type content: str
+        :param str content: string to be sent to the forked command
         """
         try:
             self.process.stdin.write(content)
-        except IOError, e:
+        except IOError as e:
             # There was a problem with the child process. It probably
             # died and we can't proceed. The best option here is to
             # raise an exception informing the user that the informed
@@ -76,18 +71,16 @@ class ProxyCommand(object):
         """
         Read from the standard output of the forked program.
 
-        @param size: how many chars should be read
-        @type size: int
+        :param int size: how many chars should be read
 
-        @return: the length of the read content
-        @rtype: int
+        :return: the length of the read content, as an `int`
         """
         try:
             start = datetime.now()
             while len(self.buffer) < size:
                 if self.timeout is not None:
                     elapsed = (datetime.now() - start).microseconds
-                    timeout = self.timeout * 1000 * 1000 # to microseconds
+                    timeout = self.timeout * 1000 * 1000  # to microseconds
                     if elapsed >= timeout:
                         raise socket.timeout()
                 r, w, x = select([self.process.stdout], [], [], 0.0)
@@ -101,8 +94,8 @@ class ProxyCommand(object):
             self.buffer = []
             return result
         except socket.timeout:
-            raise # socket.timeout is a subclass of IOError
-        except IOError, e:
+            raise  # socket.timeout is a subclass of IOError
+        except IOError as e:
             raise ProxyCommandFailure(' '.join(self.cmd), e.strerror)
 
     def close(self):
diff --git a/paramiko/py3compat.py b/paramiko/py3compat.py
new file mode 100644
index 0000000..8842b98
--- /dev/null
+++ b/paramiko/py3compat.py
@@ -0,0 +1,162 @@
+import sys
+import base64
+
+__all__ = ['PY2', 'string_types', 'integer_types', 'text_type', 'bytes_types', 'bytes', 'long', 'input',
+           'decodebytes', 'encodebytes', 'bytestring', 'byte_ord', 'byte_chr', 'byte_mask',
+           'b', 'u', 'b2s', 'StringIO', 'BytesIO', 'is_callable', 'MAXSIZE', 'next']
+
+PY2 = sys.version_info[0] < 3
+
+if PY2:
+    string_types = basestring
+    text_type = unicode
+    bytes_types = str
+    bytes = str
+    integer_types = (int, long)
+    long = long
+    input = raw_input
+    decodebytes = base64.decodestring
+    encodebytes = base64.encodestring
+
+
+    def bytestring(s):  # NOQA
+        if isinstance(s, unicode):
+            return s.encode('utf-8')
+        return s
+
+
+    byte_ord = ord  # NOQA
+    byte_chr = chr  # NOQA
+
+
+    def byte_mask(c, mask):
+        return chr(ord(c) & mask)
+
+
+    def b(s, encoding='utf8'):  # NOQA
+        """cast unicode or bytes to bytes"""
+        if isinstance(s, str):
+            return s
+        elif isinstance(s, unicode):
+            return s.encode(encoding)
+        else:
+            raise TypeError("Expected unicode or bytes, got %r" % s)
+
+
+    def u(s, encoding='utf8'):  # NOQA
+        """cast bytes or unicode to unicode"""
+        if isinstance(s, str):
+            return s.decode(encoding)
+        elif isinstance(s, unicode):
+            return s
+        else:
+            raise TypeError("Expected unicode or bytes, got %r" % s)
+
+
+    def b2s(s):
+        return s
+
+
+    try:
+        import cStringIO
+
+        StringIO = cStringIO.StringIO   # NOQA
+    except ImportError:
+        import StringIO
+
+        StringIO = StringIO.StringIO    # NOQA
+
+    BytesIO = StringIO
+
+
+    def is_callable(c):  # NOQA
+        return callable(c)
+
+
+    def get_next(c):  # NOQA
+        return c.next
+
+
+    def next(c):
+        return c.next()
+
+    # It's possible to have sizeof(long) != sizeof(Py_ssize_t).
+    class X(object):
+        def __len__(self):
+            return 1 << 31
+
+
+    try:
+        len(X())
+    except OverflowError:
+        # 32-bit
+        MAXSIZE = int((1 << 31) - 1)        # NOQA
+    else:
+        # 64-bit
+        MAXSIZE = int((1 << 63) - 1)        # NOQA
+    del X
+else:
+    import collections
+    import struct
+    string_types = str
+    text_type = str
+    bytes = bytes
+    bytes_types = bytes
+    integer_types = int
+    class long(int):
+        pass
+    input = input
+    decodebytes = base64.decodebytes
+    encodebytes = base64.encodebytes
+
+    def bytestring(s):
+        return s
+
+    def byte_ord(c):
+        # In case we're handed a string instead of an int.
+        if not isinstance(c, int):
+            c = ord(c)
+        return c
+
+    def byte_chr(c):
+        assert isinstance(c, int)
+        return struct.pack('B', c)
+
+    def byte_mask(c, mask):
+        assert isinstance(c, int)
+        return struct.pack('B', c & mask)
+
+    def b(s, encoding='utf8'):
+        """cast unicode or bytes to bytes"""
+        if isinstance(s, bytes):
+            return s
+        elif isinstance(s, str):
+            return s.encode(encoding)
+        else:
+            raise TypeError("Expected unicode or bytes, got %r" % s)
+
+    def u(s, encoding='utf8'):
+        """cast bytes or unicode to unicode"""
+        if isinstance(s, bytes):
+            return s.decode(encoding)
+        elif isinstance(s, str):
+            return s
+        else:
+            raise TypeError("Expected unicode or bytes, got %r" % s)
+
+    def b2s(s):
+        return s.decode() if isinstance(s, bytes) else s
+
+    import io
+    StringIO = io.StringIO      # NOQA
+    BytesIO = io.BytesIO        # NOQA
+
+    def is_callable(c):
+        return isinstance(c, collections.Callable)
+
+    def get_next(c):
+        return c.__next__
+
+    next = next
+
+    MAXSIZE = sys.maxsize       # NOQA
diff --git a/paramiko/resource.py b/paramiko/resource.py
index 6ef86d8..9809afb 100644
--- a/paramiko/resource.py
+++ b/paramiko/resource.py
@@ -28,13 +28,13 @@ class ResourceManager (object):
     A registry of objects and resources that should be closed when those
     objects are deleted.
     
-    This is meant to be a safer alternative to python's C{__del__} method,
+    This is meant to be a safer alternative to Python's ``__del__`` method,
     which can cause reference cycles to never be collected.  Objects registered
     with the ResourceManager can be collected but still free resources when
     they die.
     
-    Resources are registered using L{register}, and when an object is garbage
-    collected, each registered resource is closed by having its C{close()}
+    Resources are registered using `register`, and when an object is garbage
+    collected, each registered resource is closed by having its ``close()``
     method called.  Multiple resources may be registered per object, but a
     resource will only be closed once, even if multiple objects register it.
     (The last object to register it wins.)
@@ -47,14 +47,13 @@ class ResourceManager (object):
         """
         Register a resource to be closed with an object is collected.
         
-        When the given C{obj} is garbage-collected by the python interpreter,
-        the C{resource} will be closed by having its C{close()} method called.
+        When the given ``obj`` is garbage-collected by the Python interpreter,
+        the ``resource`` will be closed by having its ``close()`` method called.
         Any exceptions are ignored.
         
-        @param obj: the object to track
-        @type obj: object
-        @param resource: the resource to close when the object is collected
-        @type resource: object
+        :param object obj: the object to track
+        :param object resource:
+            the resource to close when the object is collected
         """
         def callback(ref):
             try:
diff --git a/paramiko/rsakey.py b/paramiko/rsakey.py
index c7500f8..d1f3ecf 100644
--- a/paramiko/rsakey.py
+++ b/paramiko/rsakey.py
@@ -17,20 +17,24 @@
 # 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA.
 
 """
-L{RSAKey}
+RSA keys.
 """
 
+import os
+from hashlib import sha1
+
 from Crypto.PublicKey import RSA
-from Crypto.Hash import SHA, MD5
-from Crypto.Cipher import DES3
 
-from paramiko.common import *
 from paramiko import util
+from paramiko.common import max_byte, zero_byte, one_byte
 from paramiko.message import Message
 from paramiko.ber import BER, BERException
 from paramiko.pkey import PKey
+from paramiko.py3compat import long
 from paramiko.ssh_exception import SSHException
 
+SHA1_DIGESTINFO = b'\x30\x21\x30\x09\x06\x05\x2b\x0e\x03\x02\x1a\x05\x00\x04\x14'
+
 
 class RSAKey (PKey):
     """
@@ -57,18 +61,21 @@ class RSAKey (PKey):
         else:
             if msg is None:
                 raise SSHException('Key object may not be empty')
-            if msg.get_string() != 'ssh-rsa':
+            if msg.get_text() != 'ssh-rsa':
                 raise SSHException('Invalid key')
             self.e = msg.get_mpint()
             self.n = msg.get_mpint()
         self.size = util.bit_length(self.n)
 
-    def __str__(self):
+    def asbytes(self):
         m = Message()
         m.add_string('ssh-rsa')
         m.add_mpint(self.e)
         m.add_mpint(self.n)
-        return str(m)
+        return m.asbytes()
+
+    def __str__(self):
+        return self.asbytes()
 
     def __hash__(self):
         h = hash(self.get_name())
@@ -85,42 +92,42 @@ class RSAKey (PKey):
     def can_sign(self):
         return self.d is not None
 
-    def sign_ssh_data(self, rpool, data):
-        digest = SHA.new(data).digest()
+    def sign_ssh_data(self, data):
+        digest = sha1(data).digest()
         rsa = RSA.construct((long(self.n), long(self.e), long(self.d)))
-        sig = util.deflate_long(rsa.sign(self._pkcs1imify(digest), '')[0], 0)
+        sig = util.deflate_long(rsa.sign(self._pkcs1imify(digest), bytes())[0], 0)
         m = Message()
         m.add_string('ssh-rsa')
         m.add_string(sig)
         return m
 
     def verify_ssh_sig(self, data, msg):
-        if msg.get_string() != 'ssh-rsa':
+        if msg.get_text() != 'ssh-rsa':
             return False
-        sig = util.inflate_long(msg.get_string(), True)
+        sig = util.inflate_long(msg.get_binary(), True)
         # verify the signature by SHA'ing the data and encrypting it using the
         # public key.  some wackiness ensues where we "pkcs1imify" the 20-byte
         # hash into a string as long as the RSA key.
-        hash_obj = util.inflate_long(self._pkcs1imify(SHA.new(data).digest()), True)
+        hash_obj = util.inflate_long(self._pkcs1imify(sha1(data).digest()), True)
         rsa = RSA.construct((long(self.n), long(self.e)))
         return rsa.verify(hash_obj, (sig,))
 
     def _encode_key(self):
         if (self.p is None) or (self.q is None):
             raise SSHException('Not enough key info to write private key file')
-        keylist = [ 0, self.n, self.e, self.d, self.p, self.q,
-                    self.d % (self.p - 1), self.d % (self.q - 1),
-                    util.mod_inverse(self.q, self.p) ]
+        keylist = [0, self.n, self.e, self.d, self.p, self.q,
+                   self.d % (self.p - 1), self.d % (self.q - 1),
+                   util.mod_inverse(self.q, self.p)]
         try:
             b = BER()
             b.encode(keylist)
         except BERException:
             raise SSHException('Unable to create ber encoding of key')
-        return str(b)
+        return b.asbytes()
 
     def write_private_key_file(self, filename, password=None):
         self._write_private_key_file('RSA', filename, self._encode_key(), password)
-        
+
     def write_private_key(self, file_obj, password=None):
         self._write_private_key('RSA', file_obj, self._encode_key(), password)
 
@@ -129,15 +136,13 @@ class RSAKey (PKey):
         Generate a new private RSA key.  This factory function can be used to
         generate a new host key or authentication key.
 
-        @param bits: number of bits the generated key should be.
-        @type bits: int
-        @param progress_func: an optional function to call at key points in
-            key generation (used by C{pyCrypto.PublicKey}).
-        @type progress_func: function
-        @return: new private key
-        @rtype: L{RSAKey}
+        :param int bits: number of bits the generated key should be.
+        :param function progress_func:
+            an optional function to call at key points in key generation (used
+            by ``pyCrypto.PublicKey``).
+        :return: new `.RSAKey` private key
         """
-        rsa = RSA.generate(bits, rng.read, progress_func)
+        rsa = RSA.generate(bits, os.urandom, progress_func)
         key = RSAKey(vals=(rsa.e, rsa.n))
         key.d = rsa.d
         key.p = rsa.p
@@ -145,28 +150,25 @@ class RSAKey (PKey):
         return key
     generate = staticmethod(generate)
 
-
     ###  internals...
 
-
     def _pkcs1imify(self, data):
         """
         turn a 20-byte SHA1 hash into a blob of data as large as the key's N,
         using PKCS1's \"emsa-pkcs1-v1_5\" encoding.  totally bizarre.
         """
-        SHA1_DIGESTINFO = '\x30\x21\x30\x09\x06\x05\x2b\x0e\x03\x02\x1a\x05\x00\x04\x14'
         size = len(util.deflate_long(self.n, 0))
-        filler = '\xff' * (size - len(SHA1_DIGESTINFO) - len(data) - 3)
-        return '\x00\x01' + filler + '\x00' + SHA1_DIGESTINFO + data
+        filler = max_byte * (size - len(SHA1_DIGESTINFO) - len(data) - 3)
+        return zero_byte + one_byte + filler + zero_byte + SHA1_DIGESTINFO + data
 
     def _from_private_key_file(self, filename, password):
         data = self._read_private_key_file('RSA', filename, password)
         self._decode_key(data)
-    
+
     def _from_private_key(self, file_obj, password):
         data = self._read_private_key('RSA', file_obj, password)
         self._decode_key(data)
-    
+
     def _decode_key(self, data):
         # private key file contains:
         # RSAPrivateKey = { version = 0, n, e, d, p, q, d mod p-1, d mod q-1, q**-1 mod p }
diff --git a/paramiko/server.py b/paramiko/server.py
index fdb4094..496cd60 100644
--- a/paramiko/server.py
+++ b/paramiko/server.py
@@ -17,62 +17,21 @@
 # 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA.
 
 """
-L{ServerInterface} is an interface to override for server support.
+`.ServerInterface` is an interface to override for server support.
 """
 
 import threading
-from paramiko.common import *
 from paramiko import util
-
-
-class InteractiveQuery (object):
-    """
-    A query (set of prompts) for a user during interactive authentication.
-    """
-    
-    def __init__(self, name='', instructions='', *prompts):
-        """
-        Create a new interactive query to send to the client.  The name and
-        instructions are optional, but are generally displayed to the end
-        user.  A list of prompts may be included, or they may be added via
-        the L{add_prompt} method.
-        
-        @param name: name of this query
-        @type name: str
-        @param instructions: user instructions (usually short) about this query
-        @type instructions: str
-        @param prompts: one or more authentication prompts
-        @type prompts: str
-        """
-        self.name = name
-        self.instructions = instructions
-        self.prompts = []
-        for x in prompts:
-            if (type(x) is str) or (type(x) is unicode):
-                self.add_prompt(x)
-            else:
-                self.add_prompt(x[0], x[1])
-    
-    def add_prompt(self, prompt, echo=True):
-        """
-        Add a prompt to this query.  The prompt should be a (reasonably short)
-        string.  Multiple prompts can be added to the same query.
-        
-        @param prompt: the user prompt
-        @type prompt: str
-        @param echo: C{True} (default) if the user's response should be echoed;
-            C{False} if not (for a password or similar)
-        @type echo: bool
-        """
-        self.prompts.append((prompt, echo))
+from paramiko.common import DEBUG, ERROR, OPEN_FAILED_ADMINISTRATIVELY_PROHIBITED, AUTH_FAILED
+from paramiko.py3compat import string_types
 
 
 class ServerInterface (object):
     """
-    This class defines an interface for controlling the behavior of paramiko
+    This class defines an interface for controlling the behavior of Paramiko
     in server mode.
 
-    Methods on this class are called from paramiko's primary thread, so you
+    Methods on this class are called from Paramiko's primary thread, so you
     shouldn't do too much work in them.  (Certainly nothing that blocks or
     sleeps.)
     """
@@ -80,7 +39,7 @@ class ServerInterface (object):
     def check_channel_request(self, kind, chanid):
         """
         Determine if a channel request of a given type will be granted, and
-        return C{OPEN_SUCCEEDED} or an error code.  This method is
+        return ``OPEN_SUCCEEDED`` or an error code.  This method is
         called in server mode when the client requests a channel, after
         authentication is complete.
 
@@ -88,37 +47,37 @@ class ServerInterface (object):
         useless), you should also override some of the channel request methods
         below, which are used to determine which services will be allowed on
         a given channel:
-            - L{check_channel_pty_request}
-            - L{check_channel_shell_request}
-            - L{check_channel_subsystem_request}
-            - L{check_channel_window_change_request}
-            - L{check_channel_x11_request}
-            - L{check_channel_forward_agent_request}
-
-        The C{chanid} parameter is a small number that uniquely identifies the
-        channel within a L{Transport}.  A L{Channel} object is not created
-        unless this method returns C{OPEN_SUCCEEDED} -- once a
-        L{Channel} object is created, you can call L{Channel.get_id} to
+
+            - `check_channel_pty_request`
+            - `check_channel_shell_request`
+            - `check_channel_subsystem_request`
+            - `check_channel_window_change_request`
+            - `check_channel_x11_request`
+            - `check_channel_forward_agent_request`
+
+        The ``chanid`` parameter is a small number that uniquely identifies the
+        channel within a `.Transport`.  A `.Channel` object is not created
+        unless this method returns ``OPEN_SUCCEEDED`` -- once a
+        `.Channel` object is created, you can call `.Channel.get_id` to
         retrieve the channel ID.
 
-        The return value should either be C{OPEN_SUCCEEDED} (or
-        C{0}) to allow the channel request, or one of the following error
+        The return value should either be ``OPEN_SUCCEEDED`` (or
+        ``0``) to allow the channel request, or one of the following error
         codes to reject it:
-            - C{OPEN_FAILED_ADMINISTRATIVELY_PROHIBITED}
-            - C{OPEN_FAILED_CONNECT_FAILED}
-            - C{OPEN_FAILED_UNKNOWN_CHANNEL_TYPE}
-            - C{OPEN_FAILED_RESOURCE_SHORTAGE}
+
+            - ``OPEN_FAILED_ADMINISTRATIVELY_PROHIBITED``
+            - ``OPEN_FAILED_CONNECT_FAILED``
+            - ``OPEN_FAILED_UNKNOWN_CHANNEL_TYPE``
+            - ``OPEN_FAILED_RESOURCE_SHORTAGE``
         
         The default implementation always returns
-        C{OPEN_FAILED_ADMINISTRATIVELY_PROHIBITED}.
+        ``OPEN_FAILED_ADMINISTRATIVELY_PROHIBITED``.
 
-        @param kind: the kind of channel the client would like to open
-            (usually C{"session"}).
-        @type kind: str
-        @param chanid: ID of the channel
-        @type chanid: int
-        @return: a success or failure code (listed above)
-        @rtype: int
+        :param str kind:
+            the kind of channel the client would like to open (usually
+            ``"session"``).
+        :param int chanid: ID of the channel
+        :return: an `int` success or failure code (listed above)
         """
         return OPEN_FAILED_ADMINISTRATIVELY_PROHIBITED
 
@@ -129,15 +88,13 @@ class ServerInterface (object):
         of authentication methods that might be successful.
 
         The "list" is actually a string of comma-separated names of types of
-        authentication.  Possible values are C{"password"}, C{"publickey"},
-        and C{"none"}.
+        authentication.  Possible values are ``"password"``, ``"publickey"``,
+        and ``"none"``.
 
-        The default implementation always returns C{"password"}.
+        The default implementation always returns ``"password"``.
 
-        @param username: the username requesting authentication.
-        @type username: str
-        @return: a comma-separated list of authentication types
-        @rtype: str
+        :param str username: the username requesting authentication.
+        :return: a comma-separated `str` of authentication types
         """
         return 'password'
 
@@ -146,17 +103,17 @@ class ServerInterface (object):
         Determine if a client may open channels with no (further)
         authentication.
 
-        Return L{AUTH_FAILED} if the client must authenticate, or
-        L{AUTH_SUCCESSFUL} if it's okay for the client to not
+        Return `.AUTH_FAILED` if the client must authenticate, or
+        `.AUTH_SUCCESSFUL` if it's okay for the client to not
         authenticate.
 
-        The default implementation always returns L{AUTH_FAILED}.
+        The default implementation always returns `.AUTH_FAILED`.
 
-        @param username: the username of the client.
-        @type username: str
-        @return: L{AUTH_FAILED} if the authentication fails;
-            L{AUTH_SUCCESSFUL} if it succeeds.
-        @rtype: int
+        :param str username: the username of the client.
+        :return:
+            `.AUTH_FAILED` if the authentication fails; `.AUTH_SUCCESSFUL` if
+            it succeeds.
+        :rtype: int
         """
         return AUTH_FAILED
 
@@ -165,25 +122,23 @@ class ServerInterface (object):
         Determine if a given username and password supplied by the client is
         acceptable for use in authentication.
 
-        Return L{AUTH_FAILED} if the password is not accepted,
-        L{AUTH_SUCCESSFUL} if the password is accepted and completes
-        the authentication, or L{AUTH_PARTIALLY_SUCCESSFUL} if your
+        Return `.AUTH_FAILED` if the password is not accepted,
+        `.AUTH_SUCCESSFUL` if the password is accepted and completes
+        the authentication, or `.AUTH_PARTIALLY_SUCCESSFUL` if your
         authentication is stateful, and this key is accepted for
         authentication, but more authentication is required.  (In this latter
-        case, L{get_allowed_auths} will be called to report to the client what
+        case, `get_allowed_auths` will be called to report to the client what
         options it has for continuing the authentication.)
 
-        The default implementation always returns L{AUTH_FAILED}.
+        The default implementation always returns `.AUTH_FAILED`.
 
-        @param username: the username of the authenticating client.
-        @type username: str
-        @param password: the password given by the client.
-        @type password: str
-        @return: L{AUTH_FAILED} if the authentication fails;
-            L{AUTH_SUCCESSFUL} if it succeeds;
-            L{AUTH_PARTIALLY_SUCCESSFUL} if the password auth is
+        :param str username: the username of the authenticating client.
+        :param str password: the password given by the client.
+        :return:
+            `.AUTH_FAILED` if the authentication fails; `.AUTH_SUCCESSFUL` if
+            it succeeds; `.AUTH_PARTIALLY_SUCCESSFUL` if the password auth is
             successful, but authentication must continue.
-        @rtype: int
+        :rtype: int
         """
         return AUTH_FAILED
 
@@ -194,29 +149,28 @@ class ServerInterface (object):
         check the username and key and decide if you would accept a signature
         made using this key.
 
-        Return L{AUTH_FAILED} if the key is not accepted,
-        L{AUTH_SUCCESSFUL} if the key is accepted and completes the
-        authentication, or L{AUTH_PARTIALLY_SUCCESSFUL} if your
+        Return `.AUTH_FAILED` if the key is not accepted,
+        `.AUTH_SUCCESSFUL` if the key is accepted and completes the
+        authentication, or `.AUTH_PARTIALLY_SUCCESSFUL` if your
         authentication is stateful, and this password is accepted for
         authentication, but more authentication is required.  (In this latter
-        case, L{get_allowed_auths} will be called to report to the client what
+        case, `get_allowed_auths` will be called to report to the client what
         options it has for continuing the authentication.)
 
         Note that you don't have to actually verify any key signtature here.
-        If you're willing to accept the key, paramiko will do the work of
+        If you're willing to accept the key, Paramiko will do the work of
         verifying the client's signature.
         
-        The default implementation always returns L{AUTH_FAILED}.
-
-        @param username: the username of the authenticating client
-        @type username: str
-        @param key: the key object provided by the client
-        @type key: L{PKey <pkey.PKey>}
-        @return: L{AUTH_FAILED} if the client can't authenticate
-            with this key; L{AUTH_SUCCESSFUL} if it can;
-            L{AUTH_PARTIALLY_SUCCESSFUL} if it can authenticate with
-            this key but must continue with authentication
-        @rtype: int
+        The default implementation always returns `.AUTH_FAILED`.
+
+        :param str username: the username of the authenticating client
+        :param .PKey key: the key object provided by the client
+        :return:
+            `.AUTH_FAILED` if the client can't authenticate with this key;
+            `.AUTH_SUCCESSFUL` if it can; `.AUTH_PARTIALLY_SUCCESSFUL` if it
+            can authenticate with this key but must continue with
+            authentication
+        :rtype: int
         """
         return AUTH_FAILED
     
@@ -224,24 +178,24 @@ class ServerInterface (object):
         """
         Begin an interactive authentication challenge, if supported.  You
         should override this method in server mode if you want to support the
-        C{"keyboard-interactive"} auth type, which requires you to send a
+        ``"keyboard-interactive"`` auth type, which requires you to send a
         series of questions for the client to answer.
         
-        Return L{AUTH_FAILED} if this auth method isn't supported.  Otherwise,
-        you should return an L{InteractiveQuery} object containing the prompts
+        Return `.AUTH_FAILED` if this auth method isn't supported.  Otherwise,
+        you should return an `.InteractiveQuery` object containing the prompts
         and instructions for the user.  The response will be sent via a call
-        to L{check_auth_interactive_response}.
+        to `check_auth_interactive_response`.
         
-        The default implementation always returns L{AUTH_FAILED}.
+        The default implementation always returns `.AUTH_FAILED`.
         
-        @param username: the username of the authenticating client
-        @type username: str
-        @param submethods: a comma-separated list of methods preferred by the
-            client (usually empty)
-        @type submethods: str
-        @return: L{AUTH_FAILED} if this auth method isn't supported; otherwise
-            an object containing queries for the user
-        @rtype: int or L{InteractiveQuery}
+        :param str username: the username of the authenticating client
+        :param str submethods:
+            a comma-separated list of methods preferred by the client (usually
+            empty)
+        :return:
+            `.AUTH_FAILED` if this auth method isn't supported; otherwise an
+            object containing queries for the user
+        :rtype: int or `.InteractiveQuery`
         """
         return AUTH_FAILED
     
@@ -249,31 +203,30 @@ class ServerInterface (object):
         """
         Continue or finish an interactive authentication challenge, if
         supported.  You should override this method in server mode if you want
-        to support the C{"keyboard-interactive"} auth type.
+        to support the ``"keyboard-interactive"`` auth type.
         
-        Return L{AUTH_FAILED} if the responses are not accepted,
-        L{AUTH_SUCCESSFUL} if the responses are accepted and complete
-        the authentication, or L{AUTH_PARTIALLY_SUCCESSFUL} if your
+        Return `.AUTH_FAILED` if the responses are not accepted,
+        `.AUTH_SUCCESSFUL` if the responses are accepted and complete
+        the authentication, or `.AUTH_PARTIALLY_SUCCESSFUL` if your
         authentication is stateful, and this set of responses is accepted for
         authentication, but more authentication is required.  (In this latter
-        case, L{get_allowed_auths} will be called to report to the client what
+        case, `get_allowed_auths` will be called to report to the client what
         options it has for continuing the authentication.)
 
         If you wish to continue interactive authentication with more questions,
-        you may return an L{InteractiveQuery} object, which should cause the
+        you may return an `.InteractiveQuery` object, which should cause the
         client to respond with more answers, calling this method again.  This
         cycle can continue indefinitely.
 
-        The default implementation always returns L{AUTH_FAILED}.
+        The default implementation always returns `.AUTH_FAILED`.
 
-        @param responses: list of responses from the client
-        @type responses: list(str)
-        @return: L{AUTH_FAILED} if the authentication fails;
-            L{AUTH_SUCCESSFUL} if it succeeds;
-            L{AUTH_PARTIALLY_SUCCESSFUL} if the interactive auth is
-            successful, but authentication must continue; otherwise an object
-            containing queries for the user
-        @rtype: int or L{InteractiveQuery}
+        :param list responses: list of `str` responses from the client
+        :return:
+            `.AUTH_FAILED` if the authentication fails; `.AUTH_SUCCESSFUL` if
+            it succeeds; `.AUTH_PARTIALLY_SUCCESSFUL` if the interactive auth
+            is successful, but authentication must continue; otherwise an
+            object containing queries for the user
+        :rtype: int or `.InteractiveQuery`
         """
         return AUTH_FAILED
         
@@ -281,22 +234,20 @@ class ServerInterface (object):
         """
         Handle a request for port forwarding.  The client is asking that
         connections to the given address and port be forwarded back across
-        this ssh connection.  An address of C{"0.0.0.0"} indicates a global
-        address (any address associated with this server) and a port of C{0}
+        this ssh connection.  An address of ``"0.0.0.0"`` indicates a global
+        address (any address associated with this server) and a port of ``0``
         indicates that no specific port is requested (usually the OS will pick
         a port).
         
-        The default implementation always returns C{False}, rejecting the
+        The default implementation always returns ``False``, rejecting the
         port forwarding request.  If the request is accepted, you should return
         the port opened for listening.
         
-        @param address: the requested address
-        @type address: str
-        @param port: the requested port
-        @type port: int
-        @return: the port number that was opened for listening, or C{False} to
-            reject
-        @rtype: int
+        :param str address: the requested address
+        :param int port: the requested port
+        :return:
+            the port number (`int`) that was opened for listening, or ``False``
+            to reject
         """
         return False
     
@@ -306,19 +257,17 @@ class ServerInterface (object):
         If the given address and port is being forwarded across this ssh
         connection, the port should be closed.
         
-        @param address: the forwarded address
-        @type address: str
-        @param port: the forwarded port
-        @type port: int
+        :param str address: the forwarded address
+        :param int port: the forwarded port
         """
         pass
         
     def check_global_request(self, kind, msg):
         """
-        Handle a global request of the given C{kind}.  This method is called
+        Handle a global request of the given ``kind``.  This method is called
         in server mode and client mode, whenever the remote host makes a global
         request.  If there are any arguments to the request, they will be in
-        C{msg}.
+        ``msg``.
 
         There aren't any useful global requests defined, aside from port
         forwarding, so usually this type of request is an extension to the
@@ -329,115 +278,100 @@ class ServerInterface (object):
         sent back with the successful result.  (Note that the items in the
         tuple can only be strings, ints, longs, or bools.)
 
-        The default implementation always returns C{False}, indicating that it
+        The default implementation always returns ``False``, indicating that it
         does not support any global requests.
         
-        @note: Port forwarding requests are handled separately, in
-            L{check_port_forward_request}.
-
-        @param kind: the kind of global request being made.
-        @type kind: str
-        @param msg: any extra arguments to the request.
-        @type msg: L{Message}
-        @return: C{True} or a tuple of data if the request was granted;
-            C{False} otherwise.
-        @rtype: bool
+        .. note:: Port forwarding requests are handled separately, in
+            `check_port_forward_request`.
+
+        :param str kind: the kind of global request being made.
+        :param .Message msg: any extra arguments to the request.
+        :return:
+            ``True`` or a `tuple` of data if the request was granted; ``False``
+            otherwise.
         """
         return False
 
-
     ###  Channel requests
 
-
     def check_channel_pty_request(self, channel, term, width, height, pixelwidth, pixelheight,
                                   modes):
         """
         Determine if a pseudo-terminal of the given dimensions (usually
         requested for shell access) can be provided on the given channel.
 
-        The default implementation always returns C{False}.
-
-        @param channel: the L{Channel} the pty request arrived on.
-        @type channel: L{Channel}
-        @param term: type of terminal requested (for example, C{"vt100"}).
-        @type term: str
-        @param width: width of screen in characters.
-        @type width: int
-        @param height: height of screen in characters.
-        @type height: int
-        @param pixelwidth: width of screen in pixels, if known (may be C{0} if
-            unknown).
-        @type pixelwidth: int
-        @param pixelheight: height of screen in pixels, if known (may be C{0}
-            if unknown).
-        @type pixelheight: int
-        @return: C{True} if the psuedo-terminal has been allocated; C{False}
+        The default implementation always returns ``False``.
+
+        :param .Channel channel: the `.Channel` the pty request arrived on.
+        :param str term: type of terminal requested (for example, ``"vt100"``).
+        :param int width: width of screen in characters.
+        :param int height: height of screen in characters.
+        :param int pixelwidth:
+            width of screen in pixels, if known (may be ``0`` if unknown).
+        :param int pixelheight:
+            height of screen in pixels, if known (may be ``0`` if unknown).
+        :return:
+            ``True`` if the psuedo-terminal has been allocated; ``False``
             otherwise.
-        @rtype: bool
         """
         return False
 
     def check_channel_shell_request(self, channel):
         """
         Determine if a shell will be provided to the client on the given
-        channel.  If this method returns C{True}, the channel should be
+        channel.  If this method returns ``True``, the channel should be
         connected to the stdin/stdout of a shell (or something that acts like
         a shell).
 
-        The default implementation always returns C{False}.
+        The default implementation always returns ``False``.
 
-        @param channel: the L{Channel} the request arrived on.
-        @type channel: L{Channel}
-        @return: C{True} if this channel is now hooked up to a shell; C{False}
-            if a shell can't or won't be provided.
-        @rtype: bool
+        :param .Channel channel: the `.Channel` the request arrived on.
+        :return:
+            ``True`` if this channel is now hooked up to a shell; ``False`` if
+            a shell can't or won't be provided.
         """
         return False
 
     def check_channel_exec_request(self, channel, command):
         """
         Determine if a shell command will be executed for the client.  If this
-        method returns C{True}, the channel should be connected to the stdin,
+        method returns ``True``, the channel should be connected to the stdin,
         stdout, and stderr of the shell command.
         
-        The default implementation always returns C{False}.
+        The default implementation always returns ``False``.
         
-        @param channel: the L{Channel} the request arrived on.
-        @type channel: L{Channel}
-        @param command: the command to execute.
-        @type command: str
-        @return: C{True} if this channel is now hooked up to the stdin,
-            stdout, and stderr of the executing command; C{False} if the
-            command will not be executed.
-        @rtype: bool
+        :param .Channel channel: the `.Channel` the request arrived on.
+        :param str command: the command to execute.
+        :return:
+            ``True`` if this channel is now hooked up to the stdin, stdout, and
+            stderr of the executing command; ``False`` if the command will not
+            be executed.
         
-        @since: 1.1
+        .. versionadded:: 1.1
         """
         return False
         
     def check_channel_subsystem_request(self, channel, name):
         """
         Determine if a requested subsystem will be provided to the client on
-        the given channel.  If this method returns C{True}, all future I/O
+        the given channel.  If this method returns ``True``, all future I/O
         through this channel will be assumed to be connected to the requested
-        subsystem.  An example of a subsystem is C{sftp}.
+        subsystem.  An example of a subsystem is ``sftp``.
 
         The default implementation checks for a subsystem handler assigned via
-        L{Transport.set_subsystem_handler}.
+        `.Transport.set_subsystem_handler`.
         If one has been set, the handler is invoked and this method returns
-        C{True}.  Otherwise it returns C{False}.
+        ``True``.  Otherwise it returns ``False``.
 
-        @note: Because the default implementation uses the L{Transport} to
+        .. note:: Because the default implementation uses the `.Transport` to
             identify valid subsystems, you probably won't need to override this
             method.
 
-        @param channel: the L{Channel} the pty request arrived on.
-        @type channel: L{Channel}
-        @param name: name of the requested subsystem.
-        @type name: str
-        @return: C{True} if this channel is now hooked up to the requested
-            subsystem; C{False} if that subsystem can't or won't be provided.
-        @rtype: bool
+        :param .Channel channel: the `.Channel` the pty request arrived on.
+        :param str name: name of the requested subsystem.
+        :return:
+            ``True`` if this channel is now hooked up to the requested
+            subsystem; ``False`` if that subsystem can't or won't be provided.
         """
         handler_class, larg, kwarg = channel.get_transport()._get_subsystem_handler(name)
         if handler_class is None:
@@ -451,102 +385,88 @@ class ServerInterface (object):
         Determine if the pseudo-terminal on the given channel can be resized.
         This only makes sense if a pty was previously allocated on it.
 
-        The default implementation always returns C{False}.
+        The default implementation always returns ``False``.
 
-        @param channel: the L{Channel} the pty request arrived on.
-        @type channel: L{Channel}
-        @param width: width of screen in characters.
-        @type width: int
-        @param height: height of screen in characters.
-        @type height: int
-        @param pixelwidth: width of screen in pixels, if known (may be C{0} if
-            unknown).
-        @type pixelwidth: int
-        @param pixelheight: height of screen in pixels, if known (may be C{0}
-            if unknown).
-        @type pixelheight: int
-        @return: C{True} if the terminal was resized; C{False} if not.
-        @rtype: bool
+        :param .Channel channel: the `.Channel` the pty request arrived on.
+        :param int width: width of screen in characters.
+        :param int height: height of screen in characters.
+        :param int pixelwidth:
+            width of screen in pixels, if known (may be ``0`` if unknown).
+        :param int pixelheight:
+            height of screen in pixels, if known (may be ``0`` if unknown).
+        :return: ``True`` if the terminal was resized; ``False`` if not.
         """
         return False
     
     def check_channel_x11_request(self, channel, single_connection, auth_protocol, auth_cookie, screen_number):
         """
         Determine if the client will be provided with an X11 session.  If this
-        method returns C{True}, X11 applications should be routed through new
-        SSH channels, using L{Transport.open_x11_channel}.
+        method returns ``True``, X11 applications should be routed through new
+        SSH channels, using `.Transport.open_x11_channel`.
         
-        The default implementation always returns C{False}.
+        The default implementation always returns ``False``.
         
-        @param channel: the L{Channel} the X11 request arrived on
-        @type channel: L{Channel}
-        @param single_connection: C{True} if only a single X11 channel should
-            be opened
-        @type single_connection: bool
-        @param auth_protocol: the protocol used for X11 authentication
-        @type auth_protocol: str
-        @param auth_cookie: the cookie used to authenticate to X11
-        @type auth_cookie: str
-        @param screen_number: the number of the X11 screen to connect to
-        @type screen_number: int
-        @return: C{True} if the X11 session was opened; C{False} if not
-        @rtype: bool
+        :param .Channel channel: the `.Channel` the X11 request arrived on
+        :param bool single_connection:
+            ``True`` if only a single X11 channel should be opened, else
+            ``False``.
+        :param str auth_protocol: the protocol used for X11 authentication
+        :param str auth_cookie: the cookie used to authenticate to X11
+        :param int screen_number: the number of the X11 screen to connect to
+        :return: ``True`` if the X11 session was opened; ``False`` if not
         """
         return False
 
     def check_channel_forward_agent_request(self, channel):
         """
         Determine if the client will be provided with an forward agent session.
-        If this method returns C{True}, the server will allow SSH Agent
+        If this method returns ``True``, the server will allow SSH Agent
         forwarding.
 
-        The default implementation always returns C{False}.
+        The default implementation always returns ``False``.
 
-        @param channel: the L{Channel} the request arrived on
-        @type channel: L{Channel}
-        @return: C{True} if the AgentForward was loaded; C{False} if not
-        @rtype: bool
+        :param .Channel channel: the `.Channel` the request arrived on
+        :return: ``True`` if the AgentForward was loaded; ``False`` if not
         """
         return False
 
     def check_channel_direct_tcpip_request(self, chanid, origin, destination):
         """
         Determine if a local port forwarding channel will be granted, and
-        return C{OPEN_SUCCEEDED} or an error code.  This method is
+        return ``OPEN_SUCCEEDED`` or an error code.  This method is
         called in server mode when the client requests a channel, after
         authentication is complete.
 
-        The C{chanid} parameter is a small number that uniquely identifies the
-        channel within a L{Transport}.  A L{Channel} object is not created
-        unless this method returns C{OPEN_SUCCEEDED} -- once a
-        L{Channel} object is created, you can call L{Channel.get_id} to
+        The ``chanid`` parameter is a small number that uniquely identifies the
+        channel within a `.Transport`.  A `.Channel` object is not created
+        unless this method returns ``OPEN_SUCCEEDED`` -- once a
+        `.Channel` object is created, you can call `.Channel.get_id` to
         retrieve the channel ID.
 
         The origin and destination parameters are (ip_address, port) tuples
         that correspond to both ends of the TCP connection in the forwarding
         tunnel.
 
-        The return value should either be C{OPEN_SUCCEEDED} (or
-        C{0}) to allow the channel request, or one of the following error
+        The return value should either be ``OPEN_SUCCEEDED`` (or
+        ``0``) to allow the channel request, or one of the following error
         codes to reject it:
-            - C{OPEN_FAILED_ADMINISTRATIVELY_PROHIBITED}
-            - C{OPEN_FAILED_CONNECT_FAILED}
-            - C{OPEN_FAILED_UNKNOWN_CHANNEL_TYPE}
-            - C{OPEN_FAILED_RESOURCE_SHORTAGE}
+
+            - ``OPEN_FAILED_ADMINISTRATIVELY_PROHIBITED``
+            - ``OPEN_FAILED_CONNECT_FAILED``
+            - ``OPEN_FAILED_UNKNOWN_CHANNEL_TYPE``
+            - ``OPEN_FAILED_RESOURCE_SHORTAGE``
         
         The default implementation always returns
-        C{OPEN_FAILED_ADMINISTRATIVELY_PROHIBITED}.
-
-        @param chanid: ID of the channel
-        @type chanid: int
-        @param origin: 2-tuple containing the IP address and port of the
-            originator (client side)
-        @type origin: tuple
-        @param destination: 2-tuple containing the IP address and port of the
-            destination (server side)
-        @type destination: tuple
-        @return: a success or failure code (listed above)
-        @rtype: int
+        ``OPEN_FAILED_ADMINISTRATIVELY_PROHIBITED``.
+
+        :param int chanid: ID of the channel
+        :param tuple origin:
+            2-tuple containing the IP address and port of the originator
+            (client side)
+        :param tuple destination:
+            2-tuple containing the IP address and port of the destination
+            (server side)
+        :return: an `int` success or failure code (listed above)
         """
         return OPEN_FAILED_ADMINISTRATIVELY_PROHIBITED
 
@@ -572,37 +492,71 @@ class ServerInterface (object):
         return False
 
 
+class InteractiveQuery (object):
+    """
+    A query (set of prompts) for a user during interactive authentication.
+    """
+    
+    def __init__(self, name='', instructions='', *prompts):
+        """
+        Create a new interactive query to send to the client.  The name and
+        instructions are optional, but are generally displayed to the end
+        user.  A list of prompts may be included, or they may be added via
+        the `add_prompt` method.
+        
+        :param str name: name of this query
+        :param str instructions:
+            user instructions (usually short) about this query
+        :param str prompts: one or more authentication prompts
+        """
+        self.name = name
+        self.instructions = instructions
+        self.prompts = []
+        for x in prompts:
+            if isinstance(x, string_types):
+                self.add_prompt(x)
+            else:
+                self.add_prompt(x[0], x[1])
+    
+    def add_prompt(self, prompt, echo=True):
+        """
+        Add a prompt to this query.  The prompt should be a (reasonably short)
+        string.  Multiple prompts can be added to the same query.
+        
+        :param str prompt: the user prompt
+        :param bool echo:
+            ``True`` (default) if the user's response should be echoed;
+            ``False`` if not (for a password or similar)
+        """
+        self.prompts.append((prompt, echo))
+
+
 class SubsystemHandler (threading.Thread):
     """
     Handler for a subsytem in server mode.  If you create a subclass of this
-    class and pass it to
-    L{Transport.set_subsystem_handler},
-    an object of this
+    class and pass it to `.Transport.set_subsystem_handler`, an object of this
     class will be created for each request for this subsystem.  Each new object
-    will be executed within its own new thread by calling L{start_subsystem}.
+    will be executed within its own new thread by calling `start_subsystem`.
     When that method completes, the channel is closed.
 
-    For example, if you made a subclass C{MP3Handler} and registered it as the
-    handler for subsystem C{"mp3"}, then whenever a client has successfully
-    authenticated and requests subsytem C{"mp3"}, an object of class
-    C{MP3Handler} will be created, and L{start_subsystem} will be called on
+    For example, if you made a subclass ``MP3Handler`` and registered it as the
+    handler for subsystem ``"mp3"``, then whenever a client has successfully
+    authenticated and requests subsytem ``"mp3"``, an object of class
+    ``MP3Handler`` will be created, and `start_subsystem` will be called on
     it from a new thread.
     """
     def __init__(self, channel, name, server):
         """
-        Create a new handler for a channel.  This is used by L{ServerInterface}
+        Create a new handler for a channel.  This is used by `.ServerInterface`
         to start up a new handler when a channel requests this subsystem.  You
         don't need to override this method, but if you do, be sure to pass the
-        C{channel} and C{name} parameters through to the original C{__init__}
+        ``channel`` and ``name`` parameters through to the original ``__init__``
         method here.
 
-        @param channel: the channel associated with this subsystem request.
-        @type channel: L{Channel}
-        @param name: name of the requested subsystem.
-        @type name: str
-        @param server: the server object for the session that started this
-            subsystem
-        @type server: L{ServerInterface}
+        :param .Channel channel: the channel associated with this subsystem request.
+        :param str name: name of the requested subsystem.
+        :param .ServerInterface server:
+            the server object for the session that started this subsystem
         """
         threading.Thread.__init__(self, target=self._run)
         self.__channel = channel
@@ -612,10 +566,8 @@ class SubsystemHandler (threading.Thread):
         
     def get_server(self):
         """
-        Return the L{ServerInterface} object associated with this channel and
+        Return the `.ServerInterface` object associated with this channel and
         subsystem.
-        
-        @rtype: L{ServerInterface}
         """
         return self.__server
 
@@ -623,7 +575,7 @@ class SubsystemHandler (threading.Thread):
         try:
             self.__transport._log(DEBUG, 'Starting handler for subsystem %s' % self.__name)
             self.start_subsystem(self.__name, self.__transport, self.__channel)
-        except Exception, e:
+        except Exception as e:
             self.__transport._log(ERROR, 'Exception in subsystem handler for "%s": %s' %
                                   (self.__name, str(e)))
             self.__transport._log(ERROR, util.tb_strings())
@@ -640,22 +592,20 @@ class SubsystemHandler (threading.Thread):
         subsystem is finished, this method will return.  After this method
         returns, the channel is closed.
 
-        The combination of C{transport} and C{channel} are unique; this handler
-        corresponds to exactly one L{Channel} on one L{Transport}.
+        The combination of ``transport`` and ``channel`` are unique; this handler
+        corresponds to exactly one `.Channel` on one `.Transport`.
 
-        @note: It is the responsibility of this method to exit if the
-            underlying L{Transport} is closed.  This can be done by checking
-            L{Transport.is_active} or noticing an EOF
-            on the L{Channel}.  If this method loops forever without checking
-            for this case, your python interpreter may refuse to exit because
-            this thread will still be running.
+        .. note::
+            It is the responsibility of this method to exit if the underlying
+            `.Transport` is closed.  This can be done by checking
+            `.Transport.is_active` or noticing an EOF on the `.Channel`.  If
+            this method loops forever without checking for this case, your
+            Python interpreter may refuse to exit because this thread will
+            still be running.
 
-        @param name: name of the requested subsystem.
-        @type name: str
-        @param transport: the server-mode L{Transport}.
-        @type transport: L{Transport}
-        @param channel: the channel associated with this subsystem request.
-        @type channel: L{Channel}
+        :param str name: name of the requested subsystem.
+        :param .Transport transport: the server-mode `.Transport`.
+        :param .Channel channel: the channel associated with this subsystem request.
         """
         pass
 
@@ -664,6 +614,6 @@ class SubsystemHandler (threading.Thread):
         Perform any cleanup at the end of a subsystem.  The default
         implementation just closes the channel.
 
-        @since: 1.1
+        .. versionadded:: 1.1
         """
         self.__channel.close()
diff --git a/paramiko/sftp.py b/paramiko/sftp.py
index a97c300..f44a804 100644
--- a/paramiko/sftp.py
+++ b/paramiko/sftp.py
@@ -20,32 +20,31 @@ import select
 import socket
 import struct
 
-from paramiko.common import *
 from paramiko import util
-from paramiko.channel import Channel
+from paramiko.common import asbytes, DEBUG
 from paramiko.message import Message
+from paramiko.py3compat import byte_chr, byte_ord
 
 
 CMD_INIT, CMD_VERSION, CMD_OPEN, CMD_CLOSE, CMD_READ, CMD_WRITE, CMD_LSTAT, CMD_FSTAT, \
-           CMD_SETSTAT, CMD_FSETSTAT, CMD_OPENDIR, CMD_READDIR, CMD_REMOVE, CMD_MKDIR, \
-           CMD_RMDIR, CMD_REALPATH, CMD_STAT, CMD_RENAME, CMD_READLINK, CMD_SYMLINK \
-           = range(1, 21)
+    CMD_SETSTAT, CMD_FSETSTAT, CMD_OPENDIR, CMD_READDIR, CMD_REMOVE, CMD_MKDIR, \
+    CMD_RMDIR, CMD_REALPATH, CMD_STAT, CMD_RENAME, CMD_READLINK, CMD_SYMLINK = range(1, 21)
 CMD_STATUS, CMD_HANDLE, CMD_DATA, CMD_NAME, CMD_ATTRS = range(101, 106)
 CMD_EXTENDED, CMD_EXTENDED_REPLY = range(200, 202)
 
 SFTP_OK = 0
 SFTP_EOF, SFTP_NO_SUCH_FILE, SFTP_PERMISSION_DENIED, SFTP_FAILURE, SFTP_BAD_MESSAGE, \
-         SFTP_NO_CONNECTION, SFTP_CONNECTION_LOST, SFTP_OP_UNSUPPORTED = range(1, 9)
-
-SFTP_DESC = [ 'Success',
-              'End of file',
-              'No such file',
-              'Permission denied',
-              'Failure',
-              'Bad message',
-              'No connection',
-              'Connection lost',
-              'Operation unsupported' ]
+    SFTP_NO_CONNECTION, SFTP_CONNECTION_LOST, SFTP_OP_UNSUPPORTED = range(1, 9)
+
+SFTP_DESC = ['Success',
+             'End of file',
+             'No such file',
+             'Permission denied',
+             'Failure',
+             'Bad message',
+             'No connection',
+             'Connection lost',
+             'Operation unsupported']
 
 SFTP_FLAG_READ = 0x1
 SFTP_FLAG_WRITE = 0x2
@@ -86,7 +85,7 @@ CMD_NAMES = {
     CMD_ATTRS: 'attrs',
     CMD_EXTENDED: 'extended',
     CMD_EXTENDED_REPLY: 'extended_reply'
-    }
+}
 
 
 class SFTPError (Exception):
@@ -99,10 +98,8 @@ class BaseSFTP (object):
         self.sock = None
         self.ultra_debug = False
 
-
     ###  internals...
 
-
     def _send_version(self):
         self._send_packet(CMD_INIT, struct.pack('>I', _VERSION))
         t, data = self._read_packet()
@@ -121,11 +118,11 @@ class BaseSFTP (object):
             raise SFTPError('Incompatible sftp protocol')
         version = struct.unpack('>I', data[:4])[0]
         # advertise that we support "check-file"
-        extension_pairs = [ 'check-file', 'md5,sha1' ]
+        extension_pairs = ['check-file', 'md5,sha1']
         msg = Message()
         msg.add_int(_VERSION)
         msg.add(*extension_pairs)
-        self._send_packet(CMD_VERSION, str(msg))
+        self._send_packet(CMD_VERSION, msg)
         return version
         
     def _log(self, level, msg, *args):
@@ -142,7 +139,7 @@ class BaseSFTP (object):
         return
 
     def _read_all(self, n):
-        out = ''
+        out = bytes()
         while n > 0:
             if isinstance(self.sock, socket.socket):
                 # sometimes sftp is used directly over a socket instead of
@@ -151,7 +148,7 @@ class BaseSFTP (object):
                 # return or raise an exception, but calling select on a closed
                 # socket will.)
                 while True:
-                    read, write, err = select.select([ self.sock ], [], [], 0.1)
+                    read, write, err = select.select([self.sock], [], [], 0.1)
                     if len(read) > 0:
                         x = self.sock.recv(n)
                         break
@@ -166,7 +163,8 @@ class BaseSFTP (object):
 
     def _send_packet(self, t, packet):
         #self._log(DEBUG2, 'write: %s (len=%d)' % (CMD_NAMES.get(t, '0x%02x' % t), len(packet)))
-        out = struct.pack('>I', len(packet) + 1) + chr(t) + packet
+        packet = asbytes(packet)
+        out = struct.pack('>I', len(packet) + 1) + byte_chr(t) + packet
         if self.ultra_debug:
             self._log(DEBUG, util.format_binary(out, 'OUT: '))
         self._write_all(out)
@@ -175,14 +173,14 @@ class BaseSFTP (object):
         x = self._read_all(4)
         # most sftp servers won't accept packets larger than about 32k, so
         # anything with the high byte set (> 16MB) is just garbage.
-        if x[0] != '\x00':
+        if byte_ord(x[0]):
             raise SFTPError('Garbage packet received')
         size = struct.unpack('>I', x)[0]
         data = self._read_all(size)
         if self.ultra_debug:
-            self._log(DEBUG, util.format_binary(data, 'IN: '));
+            self._log(DEBUG, util.format_binary(data, 'IN: '))
         if size > 0:
-            t = ord(data[0])
+            t = byte_ord(data[0])
             #self._log(DEBUG2, 'read: %s (len=%d)' % (CMD_NAMES.get(t), '0x%02x' % t, len(data)-1))
             return t, data[1:]
-        return 0, ''
+        return 0, bytes()
diff --git a/paramiko/sftp_attr.py b/paramiko/sftp_attr.py
index b459b04..d12eff8 100644
--- a/paramiko/sftp_attr.py
+++ b/paramiko/sftp_attr.py
@@ -18,33 +18,34 @@
 
 import stat
 import time
-from paramiko.common import *
-from paramiko.sftp import *
+from paramiko.common import x80000000, o700, o70, xffffffff
+from paramiko.py3compat import long, b
 
 
 class SFTPAttributes (object):
     """
     Representation of the attributes of a file (or proxied file) for SFTP in
     client or server mode.  It attemps to mirror the object returned by
-    C{os.stat} as closely as possible, so it may have the following fields,
-    with the same meanings as those returned by an C{os.stat} object:
-        - st_size
-        - st_uid
-        - st_gid
-        - st_mode
-        - st_atime
-        - st_mtime
+    `os.stat` as closely as possible, so it may have the following fields,
+    with the same meanings as those returned by an `os.stat` object:
+
+        - ``st_size``
+        - ``st_uid``
+        - ``st_gid``
+        - ``st_mode``
+        - ``st_atime``
+        - ``st_mtime``
 
     Because SFTP allows flags to have other arbitrary named attributes, these
-    are stored in a dict named C{attr}.  Occasionally, the filename is also
-    stored, in C{filename}.
+    are stored in a dict named ``attr``.  Occasionally, the filename is also
+    stored, in ``filename``.
     """
 
     FLAG_SIZE = 1
     FLAG_UIDGID = 2
     FLAG_PERMISSIONS = 4
     FLAG_AMTIME = 8
-    FLAG_EXTENDED = 0x80000000L
+    FLAG_EXTENDED = x80000000
 
     def __init__(self):
         """
@@ -61,15 +62,12 @@ class SFTPAttributes (object):
 
     def from_stat(cls, obj, filename=None):
         """
-        Create an SFTPAttributes object from an existing C{stat} object (an
-        object returned by C{os.stat}).
-
-        @param obj: an object returned by C{os.stat} (or equivalent).
-        @type obj: object
-        @param filename: the filename associated with this file.
-        @type filename: str
-        @return: new L{SFTPAttributes} object with the same attribute fields.
-        @rtype: L{SFTPAttributes}
+        Create an `.SFTPAttributes` object from an existing ``stat`` object (an
+        object returned by `os.stat`).
+
+        :param object obj: an object returned by `os.stat` (or equivalent).
+        :param str filename: the filename associated with this file.
+        :return: new `.SFTPAttributes` object with the same attribute fields.
         """
         attr = cls()
         attr.st_size = obj.st_size
@@ -86,10 +84,8 @@ class SFTPAttributes (object):
     def __repr__(self):
         return '<SFTPAttributes: %s>' % self._debug_str()
 
-
     ###  internals...
 
-
     def _from_msg(cls, msg, filename=None, longname=None):
         attr = cls()
         attr._unpack(msg)
@@ -143,7 +139,7 @@ class SFTPAttributes (object):
             msg.add_int(long(self.st_mtime))
         if self._flags & self.FLAG_EXTENDED:
             msg.add_int(len(self.attr))
-            for key, val in self.attr.iteritems():
+            for key, val in self.attr.items():
                 msg.add_string(key)
                 msg.add_string(val)
         return
@@ -158,7 +154,7 @@ class SFTPAttributes (object):
             out += 'mode=' + oct(self.st_mode) + ' '
         if (self.st_atime is not None) and (self.st_mtime is not None):
             out += 'atime=%d mtime=%d ' % (self.st_atime, self.st_mtime)
-        for k, v in self.attr.iteritems():
+        for k, v in self.attr.items():
             out += '"%s"=%r ' % (str(k), v)
         out += ']'
         return out
@@ -175,7 +171,7 @@ class SFTPAttributes (object):
     _rwx = staticmethod(_rwx)
 
     def __str__(self):
-        "create a unix-style long description of the file (like ls -l)"
+        """create a unix-style long description of the file (like ls -l)"""
         if self.st_mode is not None:
             kind = stat.S_IFMT(self.st_mode)
             if kind == stat.S_IFIFO:
@@ -194,13 +190,13 @@ class SFTPAttributes (object):
                 ks = 's'
             else:
                 ks = '?'
-            ks += self._rwx((self.st_mode & 0700) >> 6, self.st_mode & stat.S_ISUID)
-            ks += self._rwx((self.st_mode & 070) >> 3, self.st_mode & stat.S_ISGID)
+            ks += self._rwx((self.st_mode & o700) >> 6, self.st_mode & stat.S_ISUID)
+            ks += self._rwx((self.st_mode & o70) >> 3, self.st_mode & stat.S_ISGID)
             ks += self._rwx(self.st_mode & 7, self.st_mode & stat.S_ISVTX, True)
         else:
             ks = '?---------'
         # compute display date
-        if (self.st_mtime is None) or (self.st_mtime == 0xffffffffL):
+        if (self.st_mtime is None) or (self.st_mtime == xffffffff):
             # shouldn't really happen
             datestr = '(unknown date)'
         else:
@@ -221,3 +217,5 @@ class SFTPAttributes (object):
 
         return '%s   1 %-8d %-8d %8d %-12s %s' % (ks, uid, gid, self.st_size, datestr, filename)
 
+    def asbytes(self):
+        return b(str(self))
diff --git a/paramiko/sftp_client.py b/paramiko/sftp_client.py
index cf94582..1caaf16 100644
--- a/paramiko/sftp_client.py
+++ b/paramiko/sftp_client.py
@@ -1,6 +1,6 @@
 # Copyright (C) 2003-2007  Robey Pointer <robeypointer@gmail.com>
 #
-# This file is part of paramiko.
+# This file is part of Paramiko.
 #
 # Paramiko is free software; you can redistribute it and/or modify it under the
 # terms of the GNU Lesser General Public License as published by the Free
@@ -16,9 +16,6 @@
 # along with Paramiko; if not, write to the Free Software Foundation, Inc.,
 # 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA.
 
-"""
-Client-mode SFTP support.
-"""
 
 from binascii import hexlify
 import errno
@@ -27,8 +24,18 @@ import stat
 import threading
 import time
 import weakref
+from paramiko import util
+from paramiko.channel import Channel
+from paramiko.message import Message
+from paramiko.common import INFO, DEBUG, o777
+from paramiko.py3compat import bytestring, b, u, long, string_types, bytes_types
+from paramiko.sftp import BaseSFTP, CMD_OPENDIR, CMD_HANDLE, SFTPError, CMD_READDIR, \
+    CMD_NAME, CMD_CLOSE, SFTP_FLAG_READ, SFTP_FLAG_WRITE, SFTP_FLAG_CREATE, \
+    SFTP_FLAG_TRUNC, SFTP_FLAG_APPEND, SFTP_FLAG_EXCL, CMD_OPEN, CMD_REMOVE, \
+    CMD_RENAME, CMD_MKDIR, CMD_RMDIR, CMD_STAT, CMD_ATTRS, CMD_LSTAT, \
+    CMD_SYMLINK, CMD_SETSTAT, CMD_READLINK, CMD_REALPATH, CMD_STATUS, SFTP_OK, \
+    SFTP_EOF, SFTP_NO_SUCH_FILE, SFTP_PERMISSION_DENIED
 
-from paramiko.sftp import *
 from paramiko.sftp_attr import SFTPAttributes
 from paramiko.ssh_exception import SSHException
 from paramiko.sftp_file import SFTPFile
@@ -42,31 +49,33 @@ def _to_unicode(s):
     """
     try:
         return s.encode('ascii')
-    except UnicodeError:
+    except (UnicodeError, AttributeError):
         try:
             return s.decode('utf-8')
         except UnicodeError:
             return s
 
+b_slash = b'/'
 
-class SFTPClient (BaseSFTP):
+
+class SFTPClient(BaseSFTP):
     """
-    SFTP client object.  C{SFTPClient} is used to open an sftp session across
-    an open ssh L{Transport} and do remote file operations.
+    SFTP client object.
+    
+    Used to open an SFTP session across an open SSH `.Transport` and perform
+    remote file operations.
     """
-
     def __init__(self, sock):
         """
-        Create an SFTP client from an existing L{Channel}.  The channel
-        should already have requested the C{"sftp"} subsystem.
+        Create an SFTP client from an existing `.Channel`.  The channel
+        should already have requested the ``"sftp"`` subsystem.
 
         An alternate way to create an SFTP client context is by using
-        L{from_transport}.
+        `from_transport`.
 
-        @param sock: an open L{Channel} using the C{"sftp"} subsystem
-        @type sock: L{Channel}
+        :param .Channel sock: an open `.Channel` using the ``"sftp"`` subsystem
 
-        @raise SSHException: if there's an exception while negotiating
+        :raises SSHException: if there's an exception while negotiating
             sftp
         """
         BaseSFTP.__init__(self)
@@ -85,19 +94,18 @@ class SFTPClient (BaseSFTP):
             self.ultra_debug = transport.get_hexdump()
         try:
             server_version = self._send_version()
-        except EOFError, x:
+        except EOFError:
             raise SSHException('EOF during negotiation')
         self._log(INFO, 'Opened sftp connection (server version %d)' % server_version)
 
     def from_transport(cls, t):
         """
-        Create an SFTP client channel from an open L{Transport}.
+        Create an SFTP client channel from an open `.Transport`.
 
-        @param t: an open L{Transport} which is already authenticated
-        @type t: L{Transport}
-        @return: a new L{SFTPClient} object, referring to an sftp session
-            (channel) across the transport
-        @rtype: L{SFTPClient}
+        :param .Transport t: an open `.Transport` which is already authenticated
+        :return:
+            a new `.SFTPClient` object, referring to an sftp session (channel)
+            across the transport
         """
         chan = t.open_session()
         if chan is None:
@@ -109,84 +117,79 @@ class SFTPClient (BaseSFTP):
     def _log(self, level, msg, *args):
         if isinstance(msg, list):
             for m in msg:
-                super(SFTPClient, self)._log(level, "[chan %s] " + m, *([ self.sock.get_name() ] + list(args)))
+                self._log(level, m, *args)
         else:
-            super(SFTPClient, self)._log(level, "[chan %s] " + msg, *([ self.sock.get_name() ] + list(args)))
+            # escape '%' in msg (they could come from file or directory names) before logging
+            msg = msg.replace('%','%%')
+            super(SFTPClient, self)._log(level, "[chan %s] " + msg, *([self.sock.get_name()] + list(args)))
 
     def close(self):
         """
         Close the SFTP session and its underlying channel.
 
-        @since: 1.4
+        .. versionadded:: 1.4
         """
         self._log(INFO, 'sftp session closed.')
         self.sock.close()
 
     def get_channel(self):
         """
-        Return the underlying L{Channel} object for this SFTP session.  This
+        Return the underlying `.Channel` object for this SFTP session.  This
         might be useful for doing things like setting a timeout on the channel.
 
-        @return: the SSH channel
-        @rtype: L{Channel}
-
-        @since: 1.7.1
+        .. versionadded:: 1.7.1
         """
         return self.sock
 
     def listdir(self, path='.'):
         """
-        Return a list containing the names of the entries in the given C{path}.
+        Return a list containing the names of the entries in the given ``path``.
+
         The list is in arbitrary order.  It does not include the special
-        entries C{'.'} and C{'..'} even if they are present in the folder.
-        This method is meant to mirror C{os.listdir} as closely as possible.
-        For a list of full L{SFTPAttributes} objects, see L{listdir_attr}.
+        entries ``'.'`` and ``'..'`` even if they are present in the folder.
+        This method is meant to mirror ``os.listdir`` as closely as possible.
+        For a list of full `.SFTPAttributes` objects, see `listdir_attr`.
 
-        @param path: path to list (defaults to C{'.'})
-        @type path: str
-        @return: list of filenames
-        @rtype: list of str
+        :param str path: path to list (defaults to ``'.'``)
         """
         return [f.filename for f in self.listdir_attr(path)]
 
     def listdir_attr(self, path='.'):
         """
-        Return a list containing L{SFTPAttributes} objects corresponding to
-        files in the given C{path}.  The list is in arbitrary order.  It does
-        not include the special entries C{'.'} and C{'..'} even if they are
+        Return a list containing `.SFTPAttributes` objects corresponding to
+        files in the given ``path``.  The list is in arbitrary order.  It does
+        not include the special entries ``'.'`` and ``'..'`` even if they are
         present in the folder.
 
-        The returned L{SFTPAttributes} objects will each have an additional
-        field: C{longname}, which may contain a formatted string of the file's
+        The returned `.SFTPAttributes` objects will each have an additional
+        field: ``longname``, which may contain a formatted string of the file's
         attributes, in unix format.  The content of this string will probably
         depend on the SFTP server implementation.
 
-        @param path: path to list (defaults to C{'.'})
-        @type path: str
-        @return: list of attributes
-        @rtype: list of L{SFTPAttributes}
+        :param str path: path to list (defaults to ``'.'``)
+        :return: list of `.SFTPAttributes` objects
 
-        @since: 1.2
+        .. versionadded:: 1.2
         """
         path = self._adjust_cwd(path)
         self._log(DEBUG, 'listdir(%r)' % path)
         t, msg = self._request(CMD_OPENDIR, path)
         if t != CMD_HANDLE:
             raise SFTPError('Expected handle')
-        handle = msg.get_string()
+        handle = msg.get_binary()
         filelist = []
         while True:
             try:
                 t, msg = self._request(CMD_READDIR, handle)
-            except EOFError, e:
+            except EOFError:
                 # done with handle
                 break
             if t != CMD_NAME:
                 raise SFTPError('Expected name response')
             count = msg.get_int()
             for i in range(count):
-                filename = _to_unicode(msg.get_string())
-                longname = _to_unicode(msg.get_string())
+                filename = msg.get_text()
+                longname = msg.get_text()
                 attr = SFTPAttributes._from_msg(msg, filename, longname)
                 if (filename != '.') and (filename != '..'):
                     filelist.append(attr)
@@ -196,37 +199,34 @@ class SFTPClient (BaseSFTP):
     def open(self, filename, mode='r', bufsize=-1):
         """
         Open a file on the remote server.  The arguments are the same as for
-        python's built-in C{file} (aka C{open}).  A file-like object is
-        returned, which closely mimics the behavior of a normal python file
-        object, including the ability to be used as a context manager.
-
-        The mode indicates how the file is to be opened: C{'r'} for reading,
-        C{'w'} for writing (truncating an existing file), C{'a'} for appending,
-        C{'r+'} for reading/writing, C{'w+'} for reading/writing (truncating an
-        existing file), C{'a+'} for reading/appending.  The python C{'b'} flag
-        is ignored, since SSH treats all files as binary.  The C{'U'} flag is
-        supported in a compatible way.
-
-        Since 1.5.2, an C{'x'} flag indicates that the operation should only
+        Python's built-in `python:file` (aka `python:open`).  A file-like
+        object is returned, which closely mimics the behavior of a normal
+        Python file object, including the ability to be used as a context
+        manager.
+
+        The mode indicates how the file is to be opened: ``'r'`` for reading,
+        ``'w'`` for writing (truncating an existing file), ``'a'`` for
+        appending, ``'r+'`` for reading/writing, ``'w+'`` for reading/writing
+        (truncating an existing file), ``'a+'`` for reading/appending.  The
+        Python ``'b'`` flag is ignored, since SSH treats all files as binary.
+        The ``'U'`` flag is supported in a compatible way.
+
+        Since 1.5.2, an ``'x'`` flag indicates that the operation should only
         succeed if the file was created and did not previously exist.  This has
-        no direct mapping to python's file flags, but is commonly known as the
-        C{O_EXCL} flag in posix.
+        no direct mapping to Python's file flags, but is commonly known as the
+        ``O_EXCL`` flag in posix.
 
-        The file will be buffered in standard python style by default, but
-        can be altered with the C{bufsize} parameter.  C{0} turns off
-        buffering, C{1} uses line buffering, and any number greater than 1
-        (C{>1}) uses that specific buffer size.
+        The file will be buffered in standard Python style by default, but
+        can be altered with the ``bufsize`` parameter.  ``0`` turns off
+        buffering, ``1`` uses line buffering, and any number greater than 1
+        (``>1``) uses that specific buffer size.
 
-        @param filename: name of the file to open
-        @type filename: str
-        @param mode: mode (python-style) to open in
-        @type mode: str
-        @param bufsize: desired buffering (-1 = default buffer size)
-        @type bufsize: int
-        @return: a file object representing the open file
-        @rtype: SFTPFile
+        :param str filename: name of the file to open
+        :param str mode: mode (Python-style) to open in
+        :param int bufsize: desired buffering (-1 = default buffer size)
+        :return: an `.SFTPFile` object representing the open file
 
-        @raise IOError: if the file could not be opened.
+        :raises IOError: if the file could not be opened.
         """
         filename = self._adjust_cwd(filename)
         self._log(DEBUG, 'open(%r, %r)' % (filename, mode))
@@ -235,32 +235,31 @@ class SFTPClient (BaseSFTP):
             imode |= SFTP_FLAG_READ
         if ('w' in mode) or ('+' in mode) or ('a' in mode):
             imode |= SFTP_FLAG_WRITE
-        if ('w' in mode):
+        if 'w' in mode:
             imode |= SFTP_FLAG_CREATE | SFTP_FLAG_TRUNC
-        if ('a' in mode):
+        if 'a' in mode:
             imode |= SFTP_FLAG_CREATE | SFTP_FLAG_APPEND
-        if ('x' in mode):
+        if 'x' in mode:
             imode |= SFTP_FLAG_CREATE | SFTP_FLAG_EXCL
         attrblock = SFTPAttributes()
         t, msg = self._request(CMD_OPEN, filename, imode, attrblock)
         if t != CMD_HANDLE:
             raise SFTPError('Expected handle')
-        handle = msg.get_string()
+        handle = msg.get_binary()
         self._log(DEBUG, 'open(%r, %r) -> %s' % (filename, mode, hexlify(handle)))
         return SFTPFile(self, handle, mode, bufsize)
 
-    # python continues to vacillate about "open" vs "file"...
+    # Python continues to vacillate about "open" vs "file"...
     file = open
 
     def remove(self, path):
         """
         Remove the file at the given path.  This only works on files; for
-        removing folders (directories), use L{rmdir}.
+        removing folders (directories), use `rmdir`.
 
-        @param path: path (absolute or relative) of the file to remove
-        @type path: str
+        :param str path: path (absolute or relative) of the file to remove
 
-        @raise IOError: if the path refers to a folder (directory)
+        :raises IOError: if the path refers to a folder (directory)
         """
         path = self._adjust_cwd(path)
         self._log(DEBUG, 'remove(%r)' % path)
@@ -270,14 +269,12 @@ class SFTPClient (BaseSFTP):
 
     def rename(self, oldpath, newpath):
         """
-        Rename a file or folder from C{oldpath} to C{newpath}.
+        Rename a file or folder from ``oldpath`` to ``newpath``.
 
-        @param oldpath: existing name of the file or folder
-        @type oldpath: str
-        @param newpath: new name for the file or folder
-        @type newpath: str
+        :param str oldpath: existing name of the file or folder
+        :param str newpath: new name for the file or folder
 
-        @raise IOError: if C{newpath} is a folder, or something else goes
+        :raises IOError: if ``newpath`` is a folder, or something else goes
             wrong
         """
         oldpath = self._adjust_cwd(oldpath)
@@ -285,16 +282,14 @@ class SFTPClient (BaseSFTP):
         self._log(DEBUG, 'rename(%r, %r)' % (oldpath, newpath))
         self._request(CMD_RENAME, oldpath, newpath)
 
-    def mkdir(self, path, mode=0777):
+    def mkdir(self, path, mode=o777):
         """
-        Create a folder (directory) named C{path} with numeric mode C{mode}.
+        Create a folder (directory) named ``path`` with numeric mode ``mode``.
         The default mode is 0777 (octal).  On some systems, mode is ignored.
         Where it is used, the current umask value is first masked out.
 
-        @param path: name of the folder to create
-        @type path: str
-        @param mode: permissions (posix-style) for the newly-created folder
-        @type mode: int
+        :param str path: name of the folder to create
+        :param int mode: permissions (posix-style) for the newly-created folder
         """
         path = self._adjust_cwd(path)
         self._log(DEBUG, 'mkdir(%r, %r)' % (path, mode))
@@ -304,10 +299,9 @@ class SFTPClient (BaseSFTP):
 
     def rmdir(self, path):
         """
-        Remove the folder named C{path}.
+        Remove the folder named ``path``.
 
-        @param path: name of the folder to remove
-        @type path: str
+        :param str path: name of the folder to remove
         """
         path = self._adjust_cwd(path)
         self._log(DEBUG, 'rmdir(%r)' % path)
@@ -317,20 +311,20 @@ class SFTPClient (BaseSFTP):
         """
         Retrieve information about a file on the remote system.  The return
         value is an object whose attributes correspond to the attributes of
-        python's C{stat} structure as returned by C{os.stat}, except that it
+        Python's ``stat`` structure as returned by ``os.stat``, except that it
         contains fewer fields.  An SFTP server may return as much or as little
         info as it wants, so the results may vary from server to server.
 
-        Unlike a python C{stat} object, the result may not be accessed as a
-        tuple.  This is mostly due to the author's slack factor.
+        Unlike a Python `python:stat` object, the result may not be accessed as
+        a tuple.  This is mostly due to the author's slack factor.
 
-        The fields supported are: C{st_mode}, C{st_size}, C{st_uid}, C{st_gid},
-        C{st_atime}, and C{st_mtime}.
+        The fields supported are: ``st_mode``, ``st_size``, ``st_uid``,
+        ``st_gid``, ``st_atime``, and ``st_mtime``.
 
-        @param path: the filename to stat
-        @type path: str
-        @return: an object containing attributes about the given file
-        @rtype: SFTPAttributes
+        :param str path: the filename to stat
+        :return:
+            an `.SFTPAttributes` object containing attributes about the given
+            file
         """
         path = self._adjust_cwd(path)
         self._log(DEBUG, 'stat(%r)' % path)
@@ -343,12 +337,12 @@ class SFTPClient (BaseSFTP):
         """
         Retrieve information about a file on the remote system, without
         following symbolic links (shortcuts).  This otherwise behaves exactly
-        the same as L{stat}.
+        the same as `stat`.
 
-        @param path: the filename to stat
-        @type path: str
-        @return: an object containing attributes about the given file
-        @rtype: SFTPAttributes
+        :param str path: the filename to stat
+        :return:
+            an `.SFTPAttributes` object containing attributes about the given
+            file
         """
         path = self._adjust_cwd(path)
         self._log(DEBUG, 'lstat(%r)' % path)
@@ -359,30 +353,25 @@ class SFTPClient (BaseSFTP):
 
     def symlink(self, source, dest):
         """
-        Create a symbolic link (shortcut) of the C{source} path at
-        C{destination}.
+        Create a symbolic link (shortcut) of the ``source`` path at
+        ``destination``.
 
-        @param source: path of the original file
-        @type source: str
-        @param dest: path of the newly created symlink
-        @type dest: str
+        :param str source: path of the original file
+        :param str dest: path of the newly created symlink
         """
         dest = self._adjust_cwd(dest)
         self._log(DEBUG, 'symlink(%r, %r)' % (source, dest))
-        if type(source) is unicode:
-            source = source.encode('utf-8')
+        source = bytestring(source)
         self._request(CMD_SYMLINK, source, dest)
 
     def chmod(self, path, mode):
         """
         Change the mode (permissions) of a file.  The permissions are
-        unix-style and identical to those used by python's C{os.chmod}
+        unix-style and identical to those used by Python's `os.chmod`
         function.
 
-        @param path: path of the file to change the permissions of
-        @type path: str
-        @param mode: new permissions
-        @type mode: int
+        :param str path: path of the file to change the permissions of
+        :param int mode: new permissions
         """
         path = self._adjust_cwd(path)
         self._log(DEBUG, 'chmod(%r, %r)' % (path, mode))
@@ -392,17 +381,14 @@ class SFTPClient (BaseSFTP):
 
     def chown(self, path, uid, gid):
         """
-        Change the owner (C{uid}) and group (C{gid}) of a file.  As with
-        python's C{os.chown} function, you must pass both arguments, so if you
-        only want to change one, use L{stat} first to retrieve the current
+        Change the owner (``uid``) and group (``gid``) of a file.  As with
+        Python's `os.chown` function, you must pass both arguments, so if you
+        only want to change one, use `stat` first to retrieve the current
         owner and group.
 
-        @param path: path of the file to change the owner and group of
-        @type path: str
-        @param uid: new owner's uid
-        @type uid: int
-        @param gid: new group id
-        @type gid: int
+        :param str path: path of the file to change the owner and group of
+        :param int uid: new owner's uid
+        :param int gid: new group id
         """
         path = self._adjust_cwd(path)
         self._log(DEBUG, 'chown(%r, %r, %r)' % (path, uid, gid))
@@ -412,18 +398,17 @@ class SFTPClient (BaseSFTP):
 
     def utime(self, path, times):
         """
-        Set the access and modified times of the file specified by C{path}.  If
-        C{times} is C{None}, then the file's access and modified times are set
-        to the current time.  Otherwise, C{times} must be a 2-tuple of numbers,
-        of the form C{(atime, mtime)}, which is used to set the access and
-        modified times, respectively.  This bizarre API is mimicked from python
+        Set the access and modified times of the file specified by ``path``.  If
+        ``times`` is ``None``, then the file's access and modified times are set
+        to the current time.  Otherwise, ``times`` must be a 2-tuple of numbers,
+        of the form ``(atime, mtime)``, which is used to set the access and
+        modified times, respectively.  This bizarre API is mimicked from Python
         for the sake of consistency -- I apologize.
 
-        @param path: path of the file to modify
-        @type path: str
-        @param times: C{None} or a tuple of (access time, modified time) in
-            standard internet epoch time (seconds since 01 January 1970 GMT)
-        @type times: tuple(int)
+        :param str path: path of the file to modify
+        :param tuple times:
+            ``None`` or a tuple of (access time, modified time) in standard
+            internet epoch time (seconds since 01 January 1970 GMT)
         """
         path = self._adjust_cwd(path)
         if times is None:
@@ -435,14 +420,13 @@ class SFTPClient (BaseSFTP):
 
     def truncate(self, path, size):
         """
-        Change the size of the file specified by C{path}.  This usually extends
-        or shrinks the size of the file, just like the C{truncate()} method on
-        python file objects.
+        Change the size of the file specified by ``path``.  This usually
+        extends or shrinks the size of the file, just like the `~file.truncate`
+        method on Python file objects.
 
-        @param path: path of the file to modify
-        @type path: str
-        @param size: the new size of the file
-        @type size: int or long
+        :param str path: path of the file to modify
+        :param size: the new size of the file
+        :type size: int or long
         """
         path = self._adjust_cwd(path)
         self._log(DEBUG, 'truncate(%r, %r)' % (path, size))
@@ -453,13 +437,11 @@ class SFTPClient (BaseSFTP):
     def readlink(self, path):
         """
         Return the target of a symbolic link (shortcut).  You can use
-        L{symlink} to create these.  The result may be either an absolute or
+        `symlink` to create these.  The result may be either an absolute or
         relative pathname.
 
-        @param path: path of the symbolic link file
-        @type path: str
-        @return: target path
-        @rtype: str
+        :param str path: path of the symbolic link file
+        :return: target path, as a `str`
         """
         path = self._adjust_cwd(path)
         self._log(DEBUG, 'readlink(%r)' % path)
@@ -477,15 +459,13 @@ class SFTPClient (BaseSFTP):
         """
         Return the normalized path (on the server) of a given path.  This
         can be used to quickly resolve symbolic links or determine what the
-        server is considering to be the "current folder" (by passing C{'.'}
-        as C{path}).
+        server is considering to be the "current folder" (by passing ``'.'``
+        as ``path``).
 
-        @param path: path to be normalized
-        @type path: str
-        @return: normalized form of the given path
-        @rtype: str
+        :param str path: path to be normalized
+        :return: normalized form of the given path (as a `str`)
 
-        @raise IOError: if the path can't be resolved on the server
+        :raises IOError: if the path can't be resolved on the server
         """
         path = self._adjust_cwd(path)
         self._log(DEBUG, 'normalize(%r)' % path)
@@ -495,76 +475,72 @@ class SFTPClient (BaseSFTP):
         count = msg.get_int()
         if count != 1:
             raise SFTPError('Realpath returned %d results' % count)
-        return _to_unicode(msg.get_string())
+        return msg.get_text()
 
-    def chdir(self, path):
+    def chdir(self, path=None):
         """
         Change the "current directory" of this SFTP session.  Since SFTP
-        doesn't really have the concept of a current working directory, this
-        is emulated by paramiko.  Once you use this method to set a working
-        directory, all operations on this SFTPClient object will be relative
-        to that path. You can pass in C{None} to stop using a current working
+        doesn't really have the concept of a current working directory, this is
+        emulated by Paramiko.  Once you use this method to set a working
+        directory, all operations on this `.SFTPClient` object will be relative
+        to that path. You can pass in ``None`` to stop using a current working
         directory.
 
-        @param path: new current working directory
-        @type path: str
+        :param str path: new current working directory
 
-        @raise IOError: if the requested path doesn't exist on the server
+        :raises IOError: if the requested path doesn't exist on the server
 
-        @since: 1.4
+        .. versionadded:: 1.4
         """
         if path is None:
             self._cwd = None
             return
         if not stat.S_ISDIR(self.stat(path).st_mode):
             raise SFTPError(errno.ENOTDIR, "%s: %s" % (os.strerror(errno.ENOTDIR), path))
-        self._cwd = self.normalize(path).encode('utf-8')
+        self._cwd = b(self.normalize(path))
 
     def getcwd(self):
         """
         Return the "current working directory" for this SFTP session, as
-        emulated by paramiko.  If no directory has been set with L{chdir},
-        this method will return C{None}.
-
-        @return: the current working directory on the server, or C{None}
-        @rtype: str
+        emulated by Paramiko.  If no directory has been set with `chdir`,
+        this method will return ``None``.
 
-        @since: 1.4
+        .. versionadded:: 1.4
         """
-        return self._cwd
+        return self._cwd and u(self._cwd)
 
     def putfo(self, fl, remotepath, file_size=0, callback=None, confirm=True):
         """
-        Copy the contents of an open file object (C{fl}) to the SFTP server as
-        C{remotepath}. Any exception raised by operations will be passed through.
+        Copy the contents of an open file object (``fl``) to the SFTP server as
+        ``remotepath``. Any exception raised by operations will be passed
+        through.
 
         The SFTP operations use pipelining for speed.
 
-        @param fl: opened file or file-like object to copy
-        @type localpath: object
-        @param remotepath: the destination path on the SFTP server
-        @type remotepath: str
-        @param file_size: optional size parameter passed to callback. If none is
-            specified, size defaults to 0
-        @type file_size: int
-        @param callback: optional callback function that accepts the bytes
-            transferred so far and the total bytes to be transferred
+        :param file fl: opened file or file-like object to copy
+        :param str remotepath: the destination path on the SFTP server
+        :param int file_size:
+            optional size parameter passed to callback. If none is specified,
+            size defaults to 0
+        :param callable callback:
+            optional callback function (form: ``func(int, int)``) that accepts
+            the bytes transferred so far and the total bytes to be transferred
             (since 1.7.4)
-        @type callback: function(int, int)
-        @param confirm: whether to do a stat() on the file afterwards to
-            confirm the file size (since 1.7.7)
-        @type confirm: bool
+        :param bool confirm:
+            whether to do a stat() on the file afterwards to confirm the file
+            size (since 1.7.7)
 
-        @return: an object containing attributes about the given file
-            (since 1.7.4)
-        @rtype: SFTPAttributes
+        :return:
+            an `.SFTPAttributes` object containing attributes about the given
+            file.
 
-        @since: 1.4
+        .. versionadded:: 1.4
+        .. versionchanged:: 1.7.4
+            Began returning rich attribute objects.
         """
-        fr = self.file(remotepath, 'wb')
-        fr.set_pipelined(True)
-        size = 0
-        try:
+        with self.file(remotepath, 'wb') as fr:
+            fr.set_pipelined(True)
+            size = 0
             while True:
                 data = fl.read(32768)
                 fr.write(data)
@@ -573,8 +549,6 @@ class SFTPClient (BaseSFTP):
                     callback(size, file_size)
                 if len(data) == 0:
                     break
-        finally:
-            fr.close()
         if confirm:
             s = self.stat(remotepath)
             if s.st_size != size:
@@ -585,61 +559,55 @@ class SFTPClient (BaseSFTP):
 
     def put(self, localpath, remotepath, callback=None, confirm=True):
         """
-        Copy a local file (C{localpath}) to the SFTP server as C{remotepath}.
+        Copy a local file (``localpath``) to the SFTP server as ``remotepath``.
         Any exception raised by operations will be passed through.  This
         method is primarily provided as a convenience.
 
         The SFTP operations use pipelining for speed.
 
-        @param localpath: the local file to copy
-        @type localpath: str
-        @param remotepath: the destination path on the SFTP server
-        @type remotepath: str
-        @param callback: optional callback function that accepts the bytes
-            transferred so far and the total bytes to be transferred
-            (since 1.7.4)
-        @type callback: function(int, int)
-        @param confirm: whether to do a stat() on the file afterwards to
-            confirm the file size (since 1.7.7)
-        @type confirm: bool
+        :param str localpath: the local file to copy
+        :param str remotepath: the destination path on the SFTP server
+        :param callable callback:
+            optional callback function (form: ``func(int, int)``) that accepts
+            the bytes transferred so far and the total bytes to be transferred
+        :param bool confirm:
+            whether to do a stat() on the file afterwards to confirm the file
+            size
 
-        @return: an object containing attributes about the given file
-            (since 1.7.4)
-        @rtype: SFTPAttributes
+        :return: an `.SFTPAttributes` object containing attributes about the given file
 
-        @since: 1.4
+        .. versionadded:: 1.4
+        .. versionchanged:: 1.7.4
+            ``callback`` and rich attribute return value added.   
+        .. versionchanged:: 1.7.7
+            ``confirm`` param added.
         """
         file_size = os.stat(localpath).st_size
-        fl = file(localpath, 'rb')
-        try:
+        with open(localpath, 'rb') as fl:
             return self.putfo(fl, remotepath, os.stat(localpath).st_size, callback, confirm)
-        finally:
-            fl.close()
 
     def getfo(self, remotepath, fl, callback=None):
         """
-        Copy a remote file (C{remotepath}) from the SFTP server and write to
-        an open file or file-like object, C{fl}.  Any exception raised by
+        Copy a remote file (``remotepath``) from the SFTP server and write to
+        an open file or file-like object, ``fl``.  Any exception raised by
         operations will be passed through.  This method is primarily provided
         as a convenience.
 
-        @param remotepath: opened file or file-like object to copy to
-        @type remotepath: object
-        @param fl: the destination path on the local host or open file
-            object
-        @type localpath: str
-        @param callback: optional callback function that accepts the bytes
-            transferred so far and the total bytes to be transferred
-            (since 1.7.4)
-        @type callback: function(int, int)
-        @return: the number of bytes written to the opened file object
-
-        @since: 1.4
-        """
-        fr = self.file(remotepath, 'rb')
-        file_size = self.stat(remotepath).st_size
-        fr.prefetch()
-        try:
+        :param object remotepath: opened file or file-like object to copy to
+        :param str fl:
+            the destination path on the local host or open file object
+        :param callable callback:
+            optional callback function (form: ``func(int, int)``) that accepts
+            the bytes transferred so far and the total bytes to be transferred
+        :return: the `number <int>` of bytes written to the opened file object
+
+        .. versionadded:: 1.4
+        .. versionchanged:: 1.7.4
+            Added the ``callable`` param.
+        """
+        with self.open(remotepath, 'rb') as fr:
+            file_size = self.stat(remotepath).st_size
+            fr.prefetch()
             size = 0
             while True:
                 data = fr.read(32768)
@@ -649,41 +617,33 @@ class SFTPClient (BaseSFTP):
                     callback(size, file_size)
                 if len(data) == 0:
                     break
-        finally:
-            fr.close()
         return size
 
     def get(self, remotepath, localpath, callback=None):
         """
-        Copy a remote file (C{remotepath}) from the SFTP server to the local
-        host as C{localpath}.  Any exception raised by operations will be
+        Copy a remote file (``remotepath``) from the SFTP server to the local
+        host as ``localpath``.  Any exception raised by operations will be
         passed through.  This method is primarily provided as a convenience.
 
-        @param remotepath: the remote file to copy
-        @type remotepath: str
-        @param localpath: the destination path on the local host
-        @type localpath: str
-        @param callback: optional callback function that accepts the bytes
-            transferred so far and the total bytes to be transferred
-            (since 1.7.4)
-        @type callback: function(int, int)
+        :param str remotepath: the remote file to copy
+        :param str localpath: the destination path on the local host
+        :param callable callback:
+            optional callback function (form: ``func(int, int)``) that accepts
+            the bytes transferred so far and the total bytes to be transferred
 
-        @since: 1.4
+        .. versionadded:: 1.4
+        .. versionchanged:: 1.7.4
+            Added the ``callback`` param
         """
         file_size = self.stat(remotepath).st_size
-        fl = file(localpath, 'wb')
-        try:
+        with open(localpath, 'wb') as fl:
             size = self.getfo(remotepath, fl, callback)
-        finally:
-            fl.close()
         s = os.stat(localpath)
         if s.st_size != size:
             raise IOError('size mismatch in get!  %d != %d' % (s.st_size, size))
 
-
     ###  internals...
 
-
     def _request(self, t, *arg):
         num = self._async_request(type(None), t, *arg)
         return self._read_response(num)
@@ -695,11 +655,11 @@ class SFTPClient (BaseSFTP):
             msg = Message()
             msg.add_int(self.request_number)
             for item in arg:
-                if isinstance(item, int):
-                    msg.add_int(item)
-                elif isinstance(item, long):
+                if isinstance(item, long):
                     msg.add_int64(item)
-                elif isinstance(item, str):
+                elif isinstance(item, int):
+                    msg.add_int(item)
+                elif isinstance(item, (string_types, bytes_types)):
                     msg.add_string(item)
                 elif isinstance(item, SFTPAttributes):
                     item._pack(msg)
@@ -707,7 +667,7 @@ class SFTPClient (BaseSFTP):
                     raise Exception('unknown type for %r type %r' % (item, type(item)))
             num = self.request_number
             self._expecting[num] = fileobj
-            self._send_packet(t, str(msg))
+            self._send_packet(t, msg)
             self.request_number += 1
         finally:
             self._lock.release()
@@ -717,8 +677,8 @@ class SFTPClient (BaseSFTP):
         while True:
             try:
                 t, data = self._read_packet()
-            except EOFError, e:
-                raise SSHException('Server connection dropped: %s' % (str(e),))
+            except EOFError as e:
+                raise SSHException('Server connection dropped: %s' % str(e))
             msg = Message(data)
             num = msg.get_int()
             if num not in self._expecting:
@@ -740,7 +700,7 @@ class SFTPClient (BaseSFTP):
             if waitfor is None:
                 # just doing a single check
                 break
-        return (None, None)
+        return None, None
 
     def _finish_responses(self, fileobj):
         while fileobj in self._expecting.values():
@@ -752,7 +712,7 @@ class SFTPClient (BaseSFTP):
         Raises EOFError or IOError on error status; otherwise does nothing.
         """
         code = msg.get_int()
-        text = msg.get_string()
+        text = msg.get_text()
         if code == SFTP_OK:
             return
         elif code == SFTP_EOF:
@@ -770,18 +730,19 @@ class SFTPClient (BaseSFTP):
         Return an adjusted path if we're emulating a "current working
         directory" for the server.
         """
-        if type(path) is unicode:
-            path = path.encode('utf-8')
+        path = b(path)
         if self._cwd is None:
             return path
-        if (len(path) > 0) and (path[0] == '/'):
+        if len(path) and path[0:1] == b_slash:
             # absolute path
             return path
-        if self._cwd == '/':
+        if self._cwd == b_slash:
             return self._cwd + path
-        return self._cwd + '/' + path
+        return self._cwd + b_slash + path
 
 
-class SFTP (SFTPClient):
-    "an alias for L{SFTPClient} for backwards compatability"
+class SFTP(SFTPClient):
+    """
+    An alias for `.SFTPClient` for backwards compatability.
+    """
     pass
diff --git a/paramiko/sftp_file.py b/paramiko/sftp_file.py
index a39b1f4..03d67b3 100644
--- a/paramiko/sftp_file.py
+++ b/paramiko/sftp_file.py
@@ -17,7 +17,7 @@
 # 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA.
 
 """
-L{SFTPFile}
+SFTP file object
 """
 
 from __future__ import with_statement
@@ -27,10 +27,12 @@ from collections import deque
 import socket
 import threading
 import time
+from paramiko.common import DEBUG
 
-from paramiko.common import *
-from paramiko.sftp import *
 from paramiko.file import BufferedFile
+from paramiko.py3compat import long
+from paramiko.sftp import CMD_CLOSE, CMD_READ, CMD_DATA, SFTPError, CMD_WRITE, \
+    CMD_STATUS, CMD_FSTAT, CMD_ATTRS, CMD_FSETSTAT, CMD_EXTENDED
 from paramiko.sftp_attr import SFTPAttributes
 
 
@@ -64,6 +66,9 @@ class SFTPFile (BufferedFile):
         self._close(async=True)
     
     def close(self):
+        """
+        Close the file.
+        """
         self._close(async=False)
         
     def _close(self, async=False):
@@ -94,10 +99,10 @@ class SFTPFile (BufferedFile):
             pass
 
     def _data_in_prefetch_requests(self, offset, size):
-        k = [x for x in self._prefetch_extents.values() if x[0] <= offset]
+        k = [x for x in list(self._prefetch_extents.values()) if x[0] <= offset]
         if len(k) == 0:
             return False
-        k.sort(lambda x, y: cmp(x[0], y[0]))
+        k.sort(key=lambda x: x[0])
         buf_offset, buf_size = k[-1]
         if buf_offset + buf_size <= offset:
             # prefetch request ends before this one begins
@@ -168,7 +173,7 @@ class SFTPFile (BufferedFile):
     def _write(self, data):
         # may write less than requested if it would exceed max packet size
         chunk = min(len(data), self.MAX_REQUEST_SIZE)
-        self._reqs.append(self.sftp._async_request(type(None), CMD_WRITE, self.handle, long(self._realpos), str(data[:chunk])))
+        self._reqs.append(self.sftp._async_request(type(None), CMD_WRITE, self.handle, long(self._realpos), data[:chunk]))
         if not self.pipelined or (len(self._reqs) > 100 and self.sftp.sock.recv_ready()):
             while len(self._reqs):
                 req = self._reqs.popleft()
@@ -181,34 +186,34 @@ class SFTPFile (BufferedFile):
     def settimeout(self, timeout):
         """
         Set a timeout on read/write operations on the underlying socket or
-        ssh L{Channel}.
+        ssh `.Channel`.
 
-        @see: L{Channel.settimeout}
-        @param timeout: seconds to wait for a pending read/write operation
-            before raising C{socket.timeout}, or C{None} for no timeout
-        @type timeout: float
+        :param float timeout:
+            seconds to wait for a pending read/write operation before raising
+            ``socket.timeout``, or ``None`` for no timeout
+
+        .. seealso:: `.Channel.settimeout`
         """
         self.sftp.sock.settimeout(timeout)
 
     def gettimeout(self):
         """
-        Returns the timeout in seconds (as a float) associated with the socket
-        or ssh L{Channel} used for this file.
+        Returns the timeout in seconds (as a `float`) associated with the
+        socket or ssh `.Channel` used for this file.
 
-        @see: L{Channel.gettimeout}
-        @rtype: float
+        .. seealso:: `.Channel.gettimeout`
         """
         return self.sftp.sock.gettimeout()
 
     def setblocking(self, blocking):
         """
         Set blocking or non-blocking mode on the underiying socket or ssh
-        L{Channel}.
+        `.Channel`.
+
+        :param int blocking:
+            0 to set non-blocking mode; non-0 to set blocking mode.
 
-        @see: L{Channel.setblocking}
-        @param blocking: 0 to set non-blocking mode; non-0 to set blocking
-            mode.
-        @type blocking: int
+        .. seealso:: `.Channel.setblocking`
         """
         self.sftp.sock.setblocking(blocking)
 
@@ -221,16 +226,15 @@ class SFTPFile (BufferedFile):
             self._realpos = self._pos
         else:
             self._realpos = self._pos = self._get_size() + offset
-        self._rbuffer = ''
+        self._rbuffer = bytes()
 
     def stat(self):
         """
         Retrieve information about this file from the remote system.  This is
-        exactly like L{SFTP.stat}, except that it operates on an already-open
-        file.
+        exactly like `.SFTPClient.stat`, except that it operates on an
+        already-open file.
 
-        @return: an object containing attributes about this file.
-        @rtype: SFTPAttributes
+        :return: an `.SFTPAttributes` object containing attributes about this file.
         """
         t, msg = self.sftp._request(CMD_FSTAT, self.handle)
         if t != CMD_ATTRS:
@@ -240,11 +244,10 @@ class SFTPFile (BufferedFile):
     def chmod(self, mode):
         """
         Change the mode (permissions) of this file.  The permissions are
-        unix-style and identical to those used by python's C{os.chmod}
+        unix-style and identical to those used by Python's `os.chmod`
         function.
 
-        @param mode: new permissions
-        @type mode: int
+        :param int mode: new permissions
         """
         self.sftp._log(DEBUG, 'chmod(%s, %r)' % (hexlify(self.handle), mode))
         attr = SFTPAttributes()
@@ -253,15 +256,13 @@ class SFTPFile (BufferedFile):
         
     def chown(self, uid, gid):
         """
-        Change the owner (C{uid}) and group (C{gid}) of this file.  As with
-        python's C{os.chown} function, you must pass both arguments, so if you
-        only want to change one, use L{stat} first to retrieve the current
+        Change the owner (``uid``) and group (``gid``) of this file.  As with
+        Python's `os.chown` function, you must pass both arguments, so if you
+        only want to change one, use `stat` first to retrieve the current
         owner and group.
 
-        @param uid: new owner's uid
-        @type uid: int
-        @param gid: new group id
-        @type gid: int
+        :param int uid: new owner's uid
+        :param int gid: new group id
         """
         self.sftp._log(DEBUG, 'chown(%s, %r, %r)' % (hexlify(self.handle), uid, gid))
         attr = SFTPAttributes()
@@ -271,15 +272,15 @@ class SFTPFile (BufferedFile):
     def utime(self, times):
         """
         Set the access and modified times of this file.  If
-        C{times} is C{None}, then the file's access and modified times are set
-        to the current time.  Otherwise, C{times} must be a 2-tuple of numbers,
-        of the form C{(atime, mtime)}, which is used to set the access and
-        modified times, respectively.  This bizarre API is mimicked from python
+        ``times`` is ``None``, then the file's access and modified times are set
+        to the current time.  Otherwise, ``times`` must be a 2-tuple of numbers,
+        of the form ``(atime, mtime)``, which is used to set the access and
+        modified times, respectively.  This bizarre API is mimicked from Python
         for the sake of consistency -- I apologize.
 
-        @param times: C{None} or a tuple of (access time, modified time) in
-            standard internet epoch time (seconds since 01 January 1970 GMT)
-        @type times: tuple(int)
+        :param tuple times:
+            ``None`` or a tuple of (access time, modified time) in standard
+            internet epoch time (seconds since 01 January 1970 GMT)
         """
         if times is None:
             times = (time.time(), time.time())
@@ -291,11 +292,11 @@ class SFTPFile (BufferedFile):
     def truncate(self, size):
         """
         Change the size of this file.  This usually extends
-        or shrinks the size of the file, just like the C{truncate()} method on
-        python file objects.
+        or shrinks the size of the file, just like the ``truncate()`` method on
+        Python file objects.
         
-        @param size: the new size of the file
-        @type size: int or long
+        :param size: the new size of the file
+        :type size: int or long
         """
         self.sftp._log(DEBUG, 'truncate(%s, %r)' % (hexlify(self.handle), size))
         attr = SFTPAttributes()
@@ -308,51 +309,53 @@ class SFTPFile (BufferedFile):
         to verify a successful upload or download, or for various rsync-like
         operations.
         
-        The file is hashed from C{offset}, for C{length} bytes.  If C{length}
-        is 0, the remainder of the file is hashed.  Thus, if both C{offset}
-        and C{length} are zero, the entire file is hashed.
+        The file is hashed from ``offset``, for ``length`` bytes.  If ``length``
+        is 0, the remainder of the file is hashed.  Thus, if both ``offset``
+        and ``length`` are zero, the entire file is hashed.
         
-        Normally, C{block_size} will be 0 (the default), and this method will
+        Normally, ``block_size`` will be 0 (the default), and this method will
         return a byte string representing the requested hash (for example, a
         string of length 16 for MD5, or 20 for SHA-1).  If a non-zero
-        C{block_size} is given, each chunk of the file (from C{offset} to
-        C{offset + length}) of C{block_size} bytes is computed as a separate
+        ``block_size`` is given, each chunk of the file (from ``offset`` to
+        ``offset + length``) of ``block_size`` bytes is computed as a separate
         hash.  The hash results are all concatenated and returned as a single
         string.
         
-        For example, C{check('sha1', 0, 1024, 512)} will return a string of
+        For example, ``check('sha1', 0, 1024, 512)`` will return a string of
         length 40.  The first 20 bytes will be the SHA-1 of the first 512 bytes
         of the file, and the last 20 bytes will be the SHA-1 of the next 512
         bytes.
         
-        @param hash_algorithm: the name of the hash algorithm to use (normally
-            C{"sha1"} or C{"md5"})
-        @type hash_algorithm: str
-        @param offset: offset into the file to begin hashing (0 means to start
-            from the beginning)
-        @type offset: int or long
-        @param length: number of bytes to hash (0 means continue to the end of
-            the file)
-        @type length: int or long
-        @param block_size: number of bytes to hash per result (must not be less
-            than 256; 0 means to compute only one hash of the entire segment)
-        @type block_size: int
-        @return: string of bytes representing the hash of each block,
-            concatenated together
-        @rtype: str
+        :param str hash_algorithm:
+            the name of the hash algorithm to use (normally ``"sha1"`` or
+            ``"md5"``)
+        :param offset:
+            offset into the file to begin hashing (0 means to start from the
+            beginning)
+        :type offset: int or long
+        :param length:
+            number of bytes to hash (0 means continue to the end of the file)
+        :type length: int or long
+        :param int block_size:
+            number of bytes to hash per result (must not be less than 256; 0
+            means to compute only one hash of the entire segment)
+        :type block_size: int
+        :return:
+            `str` of bytes representing the hash of each block, concatenated
+            together
         
-        @note: Many (most?) servers don't support this extension yet.
-        
-        @raise IOError: if the server doesn't support the "check-file"
+        :raises IOError: if the server doesn't support the "check-file"
             extension, or possibly doesn't support the hash algorithm
             requested
             
-        @since: 1.4
+        .. note:: Many (most?) servers don't support this extension yet.
+        
+        .. versionadded:: 1.4
         """
         t, msg = self.sftp._request(CMD_EXTENDED, 'check-file', self.handle,
                                     hash_algorithm, long(offset), long(length), block_size)
-        ext = msg.get_string()
-        alg = msg.get_string()
+        ext = msg.get_text()
+        alg = msg.get_text()
         data = msg.get_remainder()
         return data
     
@@ -360,35 +363,35 @@ class SFTPFile (BufferedFile):
         """
         Turn on/off the pipelining of write operations to this file.  When
         pipelining is on, paramiko won't wait for the server response after
-        each write operation.  Instead, they're collected as they come in.
-        At the first non-write operation (including L{close}), all remaining
+        each write operation.  Instead, they're collected as they come in. At
+        the first non-write operation (including `.close`), all remaining
         server responses are collected.  This means that if there was an error
-        with one of your later writes, an exception might be thrown from
-        within L{close} instead of L{write}.
+        with one of your later writes, an exception might be thrown from within
+        `.close` instead of `.write`.
         
-        By default, files are I{not} pipelined.
+        By default, files are not pipelined.
         
-        @param pipelined: C{True} if pipelining should be turned on for this
-            file; C{False} otherwise
-        @type pipelined: bool
+        :param bool pipelined:
+            ``True`` if pipelining should be turned on for this file; ``False``
+            otherwise
         
-        @since: 1.5
+        .. versionadded:: 1.5
         """
         self.pipelined = pipelined
     
     def prefetch(self):
         """
-        Pre-fetch the remaining contents of this file in anticipation of
-        future L{read} calls.  If reading the entire file, pre-fetching can
+        Pre-fetch the remaining contents of this file in anticipation of future
+        `.read` calls.  If reading the entire file, pre-fetching can
         dramatically improve the download speed by avoiding roundtrip latency.
         The file's contents are incrementally buffered in a background thread.
         
-        The prefetched data is stored in a buffer until read via the L{read}
+        The prefetched data is stored in a buffer until read via the `.read`
         method.  Once data has been read, it's removed from the buffer.  The
-        data may be read in a random order (using L{seek}); chunks of the
+        data may be read in a random order (using `.seek`); chunks of the
         buffer that haven't been read will continue to be buffered.
 
-        @since: 1.5.1
+        .. versionadded:: 1.5.1
         """
         size = self.stat().st_size
         # queue up async reads for the rest of the file
@@ -404,17 +407,17 @@ class SFTPFile (BufferedFile):
     def readv(self, chunks):
         """
         Read a set of blocks from the file by (offset, length).  This is more
-        efficient than doing a series of L{seek} and L{read} calls, since the
+        efficient than doing a series of `.seek` and `.read` calls, since the
         prefetch machinery is used to retrieve all the requested blocks at
         once.
         
-        @param chunks: a list of (offset, length) tuples indicating which
-            sections of the file to read
-        @type chunks: list(tuple(long, int))
-        @return: a list of blocks read, in the same order as in C{chunks}
-        @rtype: list(str)
+        :param chunks:
+            a list of (offset, length) tuples indicating which sections of the
+            file to read
+        :type chunks: list(tuple(long, int))
+        :return: a list of blocks read, in the same order as in ``chunks``
         
-        @since: 1.5.4
+        .. versionadded:: 1.5.4
         """
         self.sftp._log(DEBUG, 'readv(%s, %r)' % (hexlify(self.handle), chunks))
 
@@ -436,11 +439,9 @@ class SFTPFile (BufferedFile):
         for x in chunks:
             self.seek(x[0])
             yield self.read(x[1])
-    
 
     ###  internals...
 
-
     def _get_size(self):
         try:
             return self.stat().st_size
@@ -468,8 +469,8 @@ class SFTPFile (BufferedFile):
             # save exception and re-raise it on next file operation
             try:
                 self.sftp._convert_status(msg)
-            except Exception, x:
-                self._saved_exception = x
+            except Exception as e:
+                self._saved_exception = e
             return
         if t != CMD_DATA:
             raise SFTPError('Expected data')
@@ -482,7 +483,7 @@ class SFTPFile (BufferedFile):
                 self._prefetch_done = True
     
     def _check_exception(self):
-        "if there's a saved exception, raise & clear it"
+        """if there's a saved exception, raise & clear it"""
         if self._saved_exception is not None:
             x = self._saved_exception
             self._saved_exception = None
diff --git a/paramiko/sftp_handle.py b/paramiko/sftp_handle.py
index 29d3d0d..92dd9cf 100644
--- a/paramiko/sftp_handle.py
+++ b/paramiko/sftp_handle.py
@@ -21,9 +21,7 @@ Abstraction of an SFTP file handle (for server mode).
 """
 
 import os
-
-from paramiko.common import *
-from paramiko.sftp import *
+from paramiko.sftp import SFTP_OP_UNSUPPORTED, SFTP_OK
 
 
 class SFTPHandle (object):
@@ -33,21 +31,20 @@ class SFTPHandle (object):
     by the client to refer to the underlying file.
     
     Server implementations can (and should) subclass SFTPHandle to implement
-    features of a file handle, like L{stat} or L{chattr}.
+    features of a file handle, like `stat` or `chattr`.
     """
     def __init__(self, flags=0):
         """
         Create a new file handle representing a local file being served over
-        SFTP.  If C{flags} is passed in, it's used to determine if the file
+        SFTP.  If ``flags`` is passed in, it's used to determine if the file
         is open in append mode.
         
-        @param flags: optional flags as passed to L{SFTPServerInterface.open}
-        @type flags: int
+        :param int flags: optional flags as passed to `.SFTPServerInterface.open`
         """
         self.__flags = flags
         self.__name = None
         # only for handles to folders:
-        self.__files = { }
+        self.__files = {}
         self.__tell = None
 
     def close(self):
@@ -56,10 +53,10 @@ class SFTPHandle (object):
         Normally you would use this method to close the underlying OS level
         file object(s).
         
-        The default implementation checks for attributes on C{self} named
-        C{readfile} and/or C{writefile}, and if either or both are present,
-        their C{close()} methods are called.  This means that if you are
-        using the default implementations of L{read} and L{write}, this
+        The default implementation checks for attributes on ``self`` named
+        ``readfile`` and/or ``writefile``, and if either or both are present,
+        their ``close()`` methods are called.  This means that if you are
+        using the default implementations of `read` and `write`, this
         method's default implementation should be fine also.
         """
         readfile = getattr(self, 'readfile', None)
@@ -71,24 +68,22 @@ class SFTPHandle (object):
 
     def read(self, offset, length):
         """
-        Read up to C{length} bytes from this file, starting at position
-        C{offset}.  The offset may be a python long, since SFTP allows it
+        Read up to ``length`` bytes from this file, starting at position
+        ``offset``.  The offset may be a Python long, since SFTP allows it
         to be 64 bits.
 
         If the end of the file has been reached, this method may return an
-        empty string to signify EOF, or it may also return L{SFTP_EOF}.
+        empty string to signify EOF, or it may also return `.SFTP_EOF`.
 
-        The default implementation checks for an attribute on C{self} named
-        C{readfile}, and if present, performs the read operation on the python
+        The default implementation checks for an attribute on ``self`` named
+        ``readfile``, and if present, performs the read operation on the Python
         file-like object found there.  (This is meant as a time saver for the
-        common case where you are wrapping a python file object.)
+        common case where you are wrapping a Python file object.)
 
-        @param offset: position in the file to start reading from.
-        @type offset: int or long
-        @param length: number of bytes to attempt to read.
-        @type length: int
-        @return: data read from the file, or an SFTP error code.
-        @rtype: str
+        :param offset: position in the file to start reading from.
+        :type offset: int or long
+        :param int length: number of bytes to attempt to read.
+        :return: data read from the file, or an SFTP error code, as a `str`.
         """
         readfile = getattr(self, 'readfile', None)
         if readfile is None:
@@ -100,7 +95,7 @@ class SFTPHandle (object):
                 readfile.seek(offset)
                 self.__tell = offset
             data = readfile.read(length)
-        except IOError, e:
+        except IOError as e:
             self.__tell = None
             return SFTPServer.convert_errno(e.errno)
         self.__tell += len(data)
@@ -108,23 +103,22 @@ class SFTPHandle (object):
 
     def write(self, offset, data):
         """
-        Write C{data} into this file at position C{offset}.  Extending the
-        file past its original end is expected.  Unlike python's normal
-        C{write()} methods, this method cannot do a partial write: it must
-        write all of C{data} or else return an error.
+        Write ``data`` into this file at position ``offset``.  Extending the
+        file past its original end is expected.  Unlike Python's normal
+        ``write()`` methods, this method cannot do a partial write: it must
+        write all of ``data`` or else return an error.
 
-        The default implementation checks for an attribute on C{self} named
-        C{writefile}, and if present, performs the write operation on the
-        python file-like object found there.  The attribute is named
-        differently from C{readfile} to make it easy to implement read-only
+        The default implementation checks for an attribute on ``self`` named
+        ``writefile``, and if present, performs the write operation on the
+        Python file-like object found there.  The attribute is named
+        differently from ``readfile`` to make it easy to implement read-only
         (or write-only) files, but if both attributes are present, they should
         refer to the same file.
         
-        @param offset: position in the file to start reading from.
-        @type offset: int or long
-        @param data: data to write into the file.
-        @type data: str
-        @return: an SFTP error code like L{SFTP_OK}.
+        :param offset: position in the file to start reading from.
+        :type offset: int or long
+        :param str data: data to write into the file.
+        :return: an SFTP error code like `.SFTP_OK`.
         """
         writefile = getattr(self, 'writefile', None)
         if writefile is None:
@@ -139,7 +133,7 @@ class SFTPHandle (object):
                     self.__tell = offset
             writefile.write(data)
             writefile.flush()
-        except IOError, e:
+        except IOError as e:
             self.__tell = None
             return SFTPServer.convert_errno(e.errno)
         if self.__tell is not None:
@@ -148,33 +142,30 @@ class SFTPHandle (object):
 
     def stat(self):
         """
-        Return an L{SFTPAttributes} object referring to this open file, or an
-        error code.  This is equivalent to L{SFTPServerInterface.stat}, except
+        Return an `.SFTPAttributes` object referring to this open file, or an
+        error code.  This is equivalent to `.SFTPServerInterface.stat`, except
         it's called on an open file instead of a path.
 
-        @return: an attributes object for the given file, or an SFTP error
-            code (like L{SFTP_PERMISSION_DENIED}).
-        @rtype: L{SFTPAttributes} I{or error code}
+        :return:
+            an attributes object for the given file, or an SFTP error code
+            (like `.SFTP_PERMISSION_DENIED`).
+        :rtype: `.SFTPAttributes` or error code
         """
         return SFTP_OP_UNSUPPORTED
 
     def chattr(self, attr):
         """
-        Change the attributes of this file.  The C{attr} object will contain
+        Change the attributes of this file.  The ``attr`` object will contain
         only those fields provided by the client in its request, so you should
         check for the presence of fields before using them.
 
-        @param attr: the attributes to change on this file.
-        @type attr: L{SFTPAttributes}
-        @return: an error code like L{SFTP_OK}.
-        @rtype: int
+        :param .SFTPAttributes attr: the attributes to change on this file.
+        :return: an `int` error code like `.SFTP_OK`.
         """
         return SFTP_OP_UNSUPPORTED
 
-
     ###  internals...
 
-    
     def _set_files(self, files):
         """
         Used by the SFTP server code to cache a directory listing.  (In
diff --git a/paramiko/sftp_server.py b/paramiko/sftp_server.py
index 1833c2e..2d8d190 100644
--- a/paramiko/sftp_server.py
+++ b/paramiko/sftp_server.py
@@ -22,46 +22,55 @@ Server-mode SFTP support.
 
 import os
 import errno
+import sys
+from hashlib import md5, sha1
 
-from Crypto.Hash import MD5, SHA
-from paramiko.common import *
+from paramiko import util
+from paramiko.sftp import BaseSFTP, Message, SFTP_FAILURE, \
+    SFTP_PERMISSION_DENIED, SFTP_NO_SUCH_FILE
+from paramiko.sftp_si import SFTPServerInterface
+from paramiko.sftp_attr import SFTPAttributes
+from paramiko.common import DEBUG
+from paramiko.py3compat import long, string_types, bytes_types, b
 from paramiko.server import SubsystemHandler
-from paramiko.sftp import *
-from paramiko.sftp_si import *
-from paramiko.sftp_attr import *
 
 
 # known hash algorithms for the "check-file" extension
+from paramiko.sftp import CMD_HANDLE, SFTP_DESC, CMD_STATUS, SFTP_EOF, CMD_NAME, \
+    SFTP_BAD_MESSAGE, CMD_EXTENDED_REPLY, SFTP_FLAG_READ, SFTP_FLAG_WRITE, \
+    SFTP_FLAG_APPEND, SFTP_FLAG_CREATE, SFTP_FLAG_TRUNC, SFTP_FLAG_EXCL, \
+    CMD_NAMES, CMD_OPEN, CMD_CLOSE, SFTP_OK, CMD_READ, CMD_DATA, CMD_WRITE, \
+    CMD_REMOVE, CMD_RENAME, CMD_MKDIR, CMD_RMDIR, CMD_OPENDIR, CMD_READDIR, \
+    CMD_STAT, CMD_ATTRS, CMD_LSTAT, CMD_FSTAT, CMD_SETSTAT, CMD_FSETSTAT, \
+    CMD_READLINK, CMD_SYMLINK, CMD_REALPATH, CMD_EXTENDED, SFTP_OP_UNSUPPORTED
+
 _hash_class = {
-    'sha1': SHA,
-    'md5': MD5,
+    'sha1': sha1,
+    'md5': md5,
 }
 
 
 class SFTPServer (BaseSFTP, SubsystemHandler):
     """
-    Server-side SFTP subsystem support.  Since this is a L{SubsystemHandler},
-    it can be (and is meant to be) set as the handler for C{"sftp"} requests.
-    Use L{Transport.set_subsystem_handler} to activate this class.
+    Server-side SFTP subsystem support.  Since this is a `.SubsystemHandler`,
+    it can be (and is meant to be) set as the handler for ``"sftp"`` requests.
+    Use `.Transport.set_subsystem_handler` to activate this class.
     """
 
     def __init__(self, channel, name, server, sftp_si=SFTPServerInterface, *largs, **kwargs):
         """
         The constructor for SFTPServer is meant to be called from within the
-        L{Transport} as a subsystem handler.  C{server} and any additional
+        `.Transport` as a subsystem handler.  ``server`` and any additional
         parameters or keyword parameters are passed from the original call to
-        L{Transport.set_subsystem_handler}.
+        `.Transport.set_subsystem_handler`.
 
-        @param channel: channel passed from the L{Transport}.
-        @type channel: L{Channel}
-        @param name: name of the requested subsystem.
-        @type name: str
-        @param server: the server object associated with this channel and
-            subsystem
-        @type server: L{ServerInterface}
-        @param sftp_si: a subclass of L{SFTPServerInterface} to use for handling
-            individual requests.
-        @type sftp_si: class
+        :param .Channel channel: channel passed from the `.Transport`.
+        :param str name: name of the requested subsystem.
+        :param .ServerInterface server:
+            the server object associated with this channel and subsystem
+        :param class sftp_si:
+            a subclass of `.SFTPServerInterface` to use for handling individual
+            requests.
         """
         BaseSFTP.__init__(self)
         SubsystemHandler.__init__(self, channel, name, server)
@@ -70,17 +79,17 @@ class SFTPServer (BaseSFTP, SubsystemHandler):
         self.ultra_debug = transport.get_hexdump()
         self.next_handle = 1
         # map of handle-string to SFTPHandle for files & folders:
-        self.file_table = { }
-        self.folder_table = { }
+        self.file_table = {}
+        self.folder_table = {}
         self.server = sftp_si(server, *largs, **kwargs)
-        
+
     def _log(self, level, msg):
         if issubclass(type(msg), list):
             for m in msg:
                 super(SFTPServer, self)._log(level, "[chan " + self.sock.get_name() + "] " + m)
         else:
             super(SFTPServer, self)._log(level, "[chan " + self.sock.get_name() + "] " + msg)
-        
+
     def start_subsystem(self, name, transport, channel):
         self.sock = channel
         self._log(DEBUG, 'Started sftp server on channel %s' % repr(channel))
@@ -92,7 +101,7 @@ class SFTPServer (BaseSFTP, SubsystemHandler):
             except EOFError:
                 self._log(DEBUG, 'EOF -- end of session')
                 return
-            except Exception, e:
+            except Exception as e:
                 self._log(DEBUG, 'Exception on channel: ' + str(e))
                 self._log(DEBUG, util.tb_strings())
                 return
@@ -100,7 +109,7 @@ class SFTPServer (BaseSFTP, SubsystemHandler):
             request_number = msg.get_int()
             try:
                 self._process(t, request_number, msg)
-            except Exception, e:
+            except Exception as e:
                 self._log(DEBUG, 'Exception in server processing: ' + str(e))
                 self._log(DEBUG, util.tb_strings())
                 # send some kind of failure message, at least
@@ -113,23 +122,21 @@ class SFTPServer (BaseSFTP, SubsystemHandler):
         self.server.session_ended()
         super(SFTPServer, self).finish_subsystem()
         # close any file handles that were left open (so we can return them to the OS quickly)
-        for f in self.file_table.itervalues():
+        for f in self.file_table.values():
             f.close()
-        for f in self.folder_table.itervalues():
+        for f in self.folder_table.values():
             f.close()
         self.file_table = {}
         self.folder_table = {}
 
     def convert_errno(e):
         """
-        Convert an errno value (as from an C{OSError} or C{IOError}) into a
+        Convert an errno value (as from an ``OSError`` or ``IOError``) into a
         standard SFTP result code.  This is a convenience function for trapping
         exceptions in server code and returning an appropriate result.
 
-        @param e: an errno code, as from C{OSError.errno}.
-        @type e: int
-        @return: an SFTP error code like L{SFTP_NO_SUCH_FILE}.
-        @rtype: int
+        :param int e: an errno code, as from ``OSError.errno``.
+        :return: an `int` SFTP error code like ``SFTP_NO_SUCH_FILE``.
         """
         if e == errno.EACCES:
             # permission denied
@@ -144,18 +151,16 @@ class SFTPServer (BaseSFTP, SubsystemHandler):
     def set_file_attr(filename, attr):
         """
         Change a file's attributes on the local filesystem.  The contents of
-        C{attr} are used to change the permissions, owner, group ownership,
+        ``attr`` are used to change the permissions, owner, group ownership,
         and/or modification & access time of the file, depending on which
-        attributes are present in C{attr}.
+        attributes are present in ``attr``.
 
         This is meant to be a handy helper function for translating SFTP file
         requests into local file operations.
-        
-        @param filename: name of the file to alter (should usually be an
-            absolute path).
-        @type filename: str
-        @param attr: attributes to change.
-        @type attr: L{SFTPAttributes}
+
+        :param str filename:
+            name of the file to alter (should usually be an absolute path).
+        :param .SFTPAttributes attr: attributes to change.
         """
         if sys.platform != 'win32':
             # mode operations are meaningless on win32
@@ -166,35 +171,34 @@ class SFTPServer (BaseSFTP, SubsystemHandler):
         if attr._flags & attr.FLAG_AMTIME:
             os.utime(filename, (attr.st_atime, attr.st_mtime))
         if attr._flags & attr.FLAG_SIZE:
-            open(filename, 'w+').truncate(attr.st_size)
+            with open(filename, 'w+') as f:
+                f.truncate(attr.st_size)
     set_file_attr = staticmethod(set_file_attr)
 
-
     ###  internals...
 
-
     def _response(self, request_number, t, *arg):
         msg = Message()
         msg.add_int(request_number)
         for item in arg:
-            if type(item) is int:
-                msg.add_int(item)
-            elif type(item) is long:
+            if isinstance(item, long):
                 msg.add_int64(item)
-            elif type(item) is str:
+            elif isinstance(item, int):
+                msg.add_int(item)
+            elif isinstance(item, (string_types, bytes_types)):
                 msg.add_string(item)
             elif type(item) is SFTPAttributes:
                 item._pack(msg)
             else:
                 raise Exception('unknown type for ' + repr(item) + ' type ' + repr(type(item)))
-        self._send_packet(t, str(msg))
+        self._send_packet(t, msg)
 
     def _send_handle_response(self, request_number, handle, folder=False):
         if not issubclass(type(handle), SFTPHandle):
             # must be error code
             self._send_status(request_number, handle)
             return
-        handle._set_name('hx%d' % self.next_handle)
+        handle._set_name(b('hx%d' % self.next_handle))
         self.next_handle += 1
         if folder:
             self.folder_table[handle._get_name()] = handle
@@ -232,16 +236,16 @@ class SFTPServer (BaseSFTP, SubsystemHandler):
         msg.add_int(len(flist))
         for attr in flist:
             msg.add_string(attr.filename)
-            msg.add_string(str(attr))
+            msg.add_string(attr)
             attr._pack(msg)
-        self._send_packet(CMD_NAME, str(msg))
+        self._send_packet(CMD_NAME, msg)
 
     def _check_file(self, request_number, msg):
         # this extension actually comes from v6 protocol, but since it's an
         # extension, i feel like we can reasonably support it backported.
         # it's very useful for verifying uploaded files or checking for
         # rsync-like differences between local and remote files.
-        handle = msg.get_string()
+        handle = msg.get_binary()
         alg_list = msg.get_list()
         start = msg.get_int64()
         length = msg.get_int64()
@@ -270,17 +274,17 @@ class SFTPServer (BaseSFTP, SubsystemHandler):
             self._send_status(request_number, SFTP_FAILURE, 'Block size too small')
             return
 
-        sum_out = ''
+        sum_out = bytes()
         offset = start
         while offset < start + length:
             blocklen = min(block_size, start + length - offset)
             # don't try to read more than about 64KB at a time
             chunklen = min(blocklen, 65536)
             count = 0
-            hash_obj = alg.new()
+            hash_obj = alg()
             while count < blocklen:
                 data = f.read(offset, chunklen)
-                if not type(data) is str:
+                if not isinstance(data, bytes_types):
                     self._send_status(request_number, data, 'Unable to hash file')
                     return
                 hash_obj.update(data)
@@ -293,10 +297,10 @@ class SFTPServer (BaseSFTP, SubsystemHandler):
         msg.add_string('check-file')
         msg.add_string(algname)
         msg.add_bytes(sum_out)
-        self._send_packet(CMD_EXTENDED_REPLY, str(msg))
-    
+        self._send_packet(CMD_EXTENDED_REPLY, msg)
+
     def _convert_pflags(self, pflags):
-        "convert SFTP-style open() flags to python's os.open() flags"
+        """convert SFTP-style open() flags to Python's os.open() flags"""
         if (pflags & SFTP_FLAG_READ) and (pflags & SFTP_FLAG_WRITE):
             flags = os.O_RDWR
         elif pflags & SFTP_FLAG_WRITE:
@@ -316,12 +320,12 @@ class SFTPServer (BaseSFTP, SubsystemHandler):
     def _process(self, t, request_number, msg):
         self._log(DEBUG, 'Request: %s' % CMD_NAMES[t])
         if t == CMD_OPEN:
-            path = msg.get_string()
+            path = msg.get_text()
             flags = self._convert_pflags(msg.get_int())
             attr = SFTPAttributes._from_msg(msg)
             self._send_handle_response(request_number, self.server.open(path, flags, attr))
         elif t == CMD_CLOSE:
-            handle = msg.get_string()
+            handle = msg.get_binary()
             if handle in self.folder_table:
                 del self.folder_table[handle]
                 self._send_status(request_number, SFTP_OK)
@@ -333,14 +337,14 @@ class SFTPServer (BaseSFTP, SubsystemHandler):
                 return
             self._send_status(request_number, SFTP_BAD_MESSAGE, 'Invalid handle')
         elif t == CMD_READ:
-            handle = msg.get_string()
+            handle = msg.get_binary()
             offset = msg.get_int64()
             length = msg.get_int()
             if handle not in self.file_table:
                 self._send_status(request_number, SFTP_BAD_MESSAGE, 'Invalid handle')
                 return
             data = self.file_table[handle].read(offset, length)
-            if type(data) is str:
+            if isinstance(data, (bytes_types, string_types)):
                 if len(data) == 0:
                     self._send_status(request_number, SFTP_EOF)
                 else:
@@ -348,54 +352,54 @@ class SFTPServer (BaseSFTP, SubsystemHandler):
             else:
                 self._send_status(request_number, data)
         elif t == CMD_WRITE:
-            handle = msg.get_string()
+            handle = msg.get_binary()
             offset = msg.get_int64()
-            data = msg.get_string()
+            data = msg.get_binary()
             if handle not in self.file_table:
                 self._send_status(request_number, SFTP_BAD_MESSAGE, 'Invalid handle')
                 return
             self._send_status(request_number, self.file_table[handle].write(offset, data))
         elif t == CMD_REMOVE:
-            path = msg.get_string()
+            path = msg.get_text()
             self._send_status(request_number, self.server.remove(path))
         elif t == CMD_RENAME:
-            oldpath = msg.get_string()
-            newpath = msg.get_string()
+            oldpath = msg.get_text()
+            newpath = msg.get_text()
             self._send_status(request_number, self.server.rename(oldpath, newpath))
         elif t == CMD_MKDIR:
-            path = msg.get_string()
+            path = msg.get_text()
             attr = SFTPAttributes._from_msg(msg)
             self._send_status(request_number, self.server.mkdir(path, attr))
         elif t == CMD_RMDIR:
-            path = msg.get_string()
+            path = msg.get_text()
             self._send_status(request_number, self.server.rmdir(path))
         elif t == CMD_OPENDIR:
-            path = msg.get_string()
+            path = msg.get_text()
             self._open_folder(request_number, path)
             return
         elif t == CMD_READDIR:
-            handle = msg.get_string()
+            handle = msg.get_binary()
             if handle not in self.folder_table:
                 self._send_status(request_number, SFTP_BAD_MESSAGE, 'Invalid handle')
                 return
             folder = self.folder_table[handle]
             self._read_folder(request_number, folder)
         elif t == CMD_STAT:
-            path = msg.get_string()
+            path = msg.get_text()
             resp = self.server.stat(path)
             if issubclass(type(resp), SFTPAttributes):
                 self._response(request_number, CMD_ATTRS, resp)
             else:
                 self._send_status(request_number, resp)
         elif t == CMD_LSTAT:
-            path = msg.get_string()
+            path = msg.get_text()
             resp = self.server.lstat(path)
             if issubclass(type(resp), SFTPAttributes):
                 self._response(request_number, CMD_ATTRS, resp)
             else:
                 self._send_status(request_number, resp)
         elif t == CMD_FSTAT:
-            handle = msg.get_string()
+            handle = msg.get_binary()
             if handle not in self.file_table:
                 self._send_status(request_number, SFTP_BAD_MESSAGE, 'Invalid handle')
                 return
@@ -405,34 +409,34 @@ class SFTPServer (BaseSFTP, SubsystemHandler):
             else:
                 self._send_status(request_number, resp)
         elif t == CMD_SETSTAT:
-            path = msg.get_string()
+            path = msg.get_text()
             attr = SFTPAttributes._from_msg(msg)
             self._send_status(request_number, self.server.chattr(path, attr))
         elif t == CMD_FSETSTAT:
-            handle = msg.get_string()
+            handle = msg.get_binary()
             attr = SFTPAttributes._from_msg(msg)
             if handle not in self.file_table:
                 self._response(request_number, SFTP_BAD_MESSAGE, 'Invalid handle')
                 return
             self._send_status(request_number, self.file_table[handle].chattr(attr))
         elif t == CMD_READLINK:
-            path = msg.get_string()
+            path = msg.get_text()
             resp = self.server.readlink(path)
-            if type(resp) is str:
+            if isinstance(resp, (bytes_types, string_types)):
                 self._response(request_number, CMD_NAME, 1, resp, '', SFTPAttributes())
             else:
                 self._send_status(request_number, resp)
         elif t == CMD_SYMLINK:
             # the sftp 2 draft is incorrect here!  path always follows target_path
-            target_path = msg.get_string()
-            path = msg.get_string()
+            target_path = msg.get_text()
+            path = msg.get_text()
             self._send_status(request_number, self.server.symlink(target_path, path))
         elif t == CMD_REALPATH:
-            path = msg.get_string()
+            path = msg.get_text()
             rpath = self.server.canonicalize(path)
             self._response(request_number, CMD_NAME, 1, rpath, '', SFTPAttributes())
         elif t == CMD_EXTENDED:
-            tag = msg.get_string()
+            tag = msg.get_text()
             if tag == 'check-file':
                 self._check_file(request_number, msg)
             else:
diff --git a/paramiko/sftp_si.py b/paramiko/sftp_si.py
index b0ee3c4..61db956 100644
--- a/paramiko/sftp_si.py
+++ b/paramiko/sftp_si.py
@@ -17,19 +17,18 @@
 # 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA.
 
 """
-L{SFTPServerInterface} is an interface to override for SFTP server support.
+An interface to override for SFTP server support.
 """
 
 import os
-
-from paramiko.common import *
-from paramiko.sftp import *
+import sys
+from paramiko.sftp import SFTP_OP_UNSUPPORTED
 
 
 class SFTPServerInterface (object):
     """
     This class defines an interface for controlling the behavior of paramiko
-    when using the L{SFTPServer} subsystem to provide an SFTP server.
+    when using the `.SFTPServer` subsystem to provide an SFTP server.
 
     Methods on this class are called from the SFTP session's thread, so you can
     block as long as necessary without affecting other sessions (even other
@@ -41,14 +40,13 @@ class SFTPServerInterface (object):
     clients & servers obey the requirement that paths be encoded in UTF-8.
     """
     
-    def __init__ (self, server, *largs, **kwargs):
+    def __init__(self, server, *largs, **kwargs):
         """
         Create a new SFTPServerInterface object.  This method does nothing by
         default and is meant to be overridden by subclasses.
         
-        @param server: the server object associated with this channel and
-            SFTP subsystem
-        @type server: L{ServerInterface}
+        :param .ServerInterface server:
+            the server object associated with this channel and SFTP subsystem
         """
         super(SFTPServerInterface, self).__init__(*largs, **kwargs)
 
@@ -64,7 +62,7 @@ class SFTPServerInterface (object):
         """
         The SFTP server session has just ended, either cleanly or via an
         exception.  This method is meant to be overridden to perform any
-        necessary cleanup before this C{SFTPServerInterface} object is
+        necessary cleanup before this `.SFTPServerInterface` object is
         destroyed.
         """
         pass
@@ -72,103 +70,105 @@ class SFTPServerInterface (object):
     def open(self, path, flags, attr):
         """
         Open a file on the server and create a handle for future operations
-        on that file.  On success, a new object subclassed from L{SFTPHandle}
+        on that file.  On success, a new object subclassed from `.SFTPHandle`
         should be returned.  This handle will be used for future operations
         on the file (read, write, etc).  On failure, an error code such as
-        L{SFTP_PERMISSION_DENIED} should be returned.
-
-        C{flags} contains the requested mode for opening (read-only,
-        write-append, etc) as a bitset of flags from the C{os} module:
-            - C{os.O_RDONLY}
-            - C{os.O_WRONLY}
-            - C{os.O_RDWR}
-            - C{os.O_APPEND}
-            - C{os.O_CREAT}
-            - C{os.O_TRUNC}
-            - C{os.O_EXCL}
-        (One of C{os.O_RDONLY}, C{os.O_WRONLY}, or C{os.O_RDWR} will always
+        `.SFTP_PERMISSION_DENIED` should be returned.
+
+        ``flags`` contains the requested mode for opening (read-only,
+        write-append, etc) as a bitset of flags from the ``os`` module:
+
+            - ``os.O_RDONLY``
+            - ``os.O_WRONLY``
+            - ``os.O_RDWR``
+            - ``os.O_APPEND``
+            - ``os.O_CREAT``
+            - ``os.O_TRUNC``
+            - ``os.O_EXCL``
+
+        (One of ``os.O_RDONLY``, ``os.O_WRONLY``, or ``os.O_RDWR`` will always
         be set.)
 
-        The C{attr} object contains requested attributes of the file if it
+        The ``attr`` object contains requested attributes of the file if it
         has to be created.  Some or all attribute fields may be missing if
         the client didn't specify them.
         
-        @note: The SFTP protocol defines all files to be in "binary" mode.
-            There is no equivalent to python's "text" mode.
-
-        @param path: the requested path (relative or absolute) of the file
-            to be opened.
-        @type path: str
-        @param flags: flags or'd together from the C{os} module indicating the
-            requested mode for opening the file.
-        @type flags: int
-        @param attr: requested attributes of the file if it is newly created.
-        @type attr: L{SFTPAttributes}
-        @return: a new L{SFTPHandle} I{or error code}.
-        @rtype L{SFTPHandle}
+        .. note:: The SFTP protocol defines all files to be in "binary" mode.
+            There is no equivalent to Python's "text" mode.
+
+        :param str path:
+            the requested path (relative or absolute) of the file to be opened.
+        :param int flags:
+            flags or'd together from the ``os`` module indicating the requested
+            mode for opening the file.
+        :param .SFTPAttributes attr:
+            requested attributes of the file if it is newly created.
+        :return: a new `.SFTPHandle` or error code.
         """
         return SFTP_OP_UNSUPPORTED
 
     def list_folder(self, path):
         """
-        Return a list of files within a given folder.  The C{path} will use
-        posix notation (C{"/"} separates folder names) and may be an absolute
+        Return a list of files within a given folder.  The ``path`` will use
+        posix notation (``"/"`` separates folder names) and may be an absolute
         or relative path.
 
-        The list of files is expected to be a list of L{SFTPAttributes}
+        The list of files is expected to be a list of `.SFTPAttributes`
         objects, which are similar in structure to the objects returned by
-        C{os.stat}.  In addition, each object should have its C{filename}
+        ``os.stat``.  In addition, each object should have its ``filename``
         field filled in, since this is important to a directory listing and
-        not normally present in C{os.stat} results.  The method
-        L{SFTPAttributes.from_stat} will usually do what you want.
+        not normally present in ``os.stat`` results.  The method
+        `.SFTPAttributes.from_stat` will usually do what you want.
 
-        In case of an error, you should return one of the C{SFTP_*} error
-        codes, such as L{SFTP_PERMISSION_DENIED}.
+        In case of an error, you should return one of the ``SFTP_*`` error
+        codes, such as `.SFTP_PERMISSION_DENIED`.
 
-        @param path: the requested path (relative or absolute) to be listed.
-        @type path: str
-        @return: a list of the files in the given folder, using
-            L{SFTPAttributes} objects.
-        @rtype: list of L{SFTPAttributes} I{or error code}
+        :param str path: the requested path (relative or absolute) to be listed.
+        :return:
+            a list of the files in the given folder, using `.SFTPAttributes`
+            objects.
         
-        @note: You should normalize the given C{path} first (see the
-        C{os.path} module) and check appropriate permissions before returning
-        the list of files.  Be careful of malicious clients attempting to use
-        relative paths to escape restricted folders, if you're doing a direct
-        translation from the SFTP server path to your local filesystem.
+        .. note::
+            You should normalize the given ``path`` first (see the `os.path`
+            module) and check appropriate permissions before returning the list
+            of files.  Be careful of malicious clients attempting to use
+            relative paths to escape restricted folders, if you're doing a
+            direct translation from the SFTP server path to your local
+            filesystem.
         """
         return SFTP_OP_UNSUPPORTED
 
     def stat(self, path):
         """
-        Return an L{SFTPAttributes} object for a path on the server, or an
+        Return an `.SFTPAttributes` object for a path on the server, or an
         error code.  If your server supports symbolic links (also known as
-        "aliases"), you should follow them.  (L{lstat} is the corresponding
+        "aliases"), you should follow them.  (`lstat` is the corresponding
         call that doesn't follow symlinks/aliases.)
 
-        @param path: the requested path (relative or absolute) to fetch
-            file statistics for.
-        @type path: str
-        @return: an attributes object for the given file, or an SFTP error
-            code (like L{SFTP_PERMISSION_DENIED}).
-        @rtype: L{SFTPAttributes} I{or error code}
+        :param str path:
+            the requested path (relative or absolute) to fetch file statistics
+            for.
+        :return:
+            an `.SFTPAttributes` object for the given file, or an SFTP error
+            code (like `.SFTP_PERMISSION_DENIED`).
         """
         return SFTP_OP_UNSUPPORTED
 
     def lstat(self, path):
         """
-        Return an L{SFTPAttributes} object for a path on the server, or an
+        Return an `.SFTPAttributes` object for a path on the server, or an
         error code.  If your server supports symbolic links (also known as
-        "aliases"), you should I{not} follow them -- instead, you should
-        return data on the symlink or alias itself.  (L{stat} is the
+        "aliases"), you should not follow them -- instead, you should
+        return data on the symlink or alias itself.  (`stat` is the
         corresponding call that follows symlinks/aliases.)
 
-        @param path: the requested path (relative or absolute) to fetch
-            file statistics for.
-        @type path: str
-        @return: an attributes object for the given file, or an SFTP error
-            code (like L{SFTP_PERMISSION_DENIED}).
-        @rtype: L{SFTPAttributes} I{or error code}
+        :param str path:
+            the requested path (relative or absolute) to fetch file statistics
+            for.
+        :type path: str
+        :return:
+            an `.SFTPAttributes` object for the given file, or an SFTP error
+            code (like `.SFTP_PERMISSION_DENIED`).
         """
         return SFTP_OP_UNSUPPORTED
 
@@ -176,11 +176,9 @@ class SFTPServerInterface (object):
         """
         Delete a file, if possible.
 
-        @param path: the requested path (relative or absolute) of the file
-            to delete.
-        @type path: str
-        @return: an SFTP error code like L{SFTP_OK}.
-        @rtype: int
+        :param str path:
+            the requested path (relative or absolute) of the file to delete.
+        :return: an SFTP error code `int` like `.SFTP_OK`.
         """
         return SFTP_OP_UNSUPPORTED
 
@@ -192,83 +190,74 @@ class SFTPServerInterface (object):
         probably a good idea to implement "move" in this method too, even for
         files that cross disk partition boundaries, if at all possible.
         
-        @note: You should return an error if a file with the same name as
-            C{newpath} already exists.  (The rename operation should be
+        .. note:: You should return an error if a file with the same name as
+            ``newpath`` already exists.  (The rename operation should be
             non-desctructive.)
 
-        @param oldpath: the requested path (relative or absolute) of the
-            existing file.
-        @type oldpath: str
-        @param newpath: the requested new path of the file.
-        @type newpath: str
-        @return: an SFTP error code like L{SFTP_OK}.
-        @rtype: int
+        :param str oldpath:
+            the requested path (relative or absolute) of the existing file.
+        :param str newpath: the requested new path of the file.
+        :return: an SFTP error code `int` like `.SFTP_OK`.
         """
         return SFTP_OP_UNSUPPORTED
 
     def mkdir(self, path, attr):
         """
-        Create a new directory with the given attributes.  The C{attr}
+        Create a new directory with the given attributes.  The ``attr``
         object may be considered a "hint" and ignored.
 
-        The C{attr} object will contain only those fields provided by the
-        client in its request, so you should use C{hasattr} to check for
-        the presense of fields before using them.  In some cases, the C{attr}
+        The ``attr`` object will contain only those fields provided by the
+        client in its request, so you should use ``hasattr`` to check for
+        the presense of fields before using them.  In some cases, the ``attr``
         object may be completely empty.
 
-        @param path: requested path (relative or absolute) of the new
-            folder.
-        @type path: str
-        @param attr: requested attributes of the new folder.
-        @type attr: L{SFTPAttributes}
-        @return: an SFTP error code like L{SFTP_OK}.
-        @rtype: int
+        :param str path:
+            requested path (relative or absolute) of the new folder.
+        :param .SFTPAttributes attr: requested attributes of the new folder.
+        :return: an SFTP error code `int` like `.SFTP_OK`.
         """
         return SFTP_OP_UNSUPPORTED
 
     def rmdir(self, path):
         """
-        Remove a directory if it exists.  The C{path} should refer to an
+        Remove a directory if it exists.  The ``path`` should refer to an
         existing, empty folder -- otherwise this method should return an
         error.
 
-        @param path: requested path (relative or absolute) of the folder
-            to remove.
-        @type path: str
-        @return: an SFTP error code like L{SFTP_OK}.
-        @rtype: int
+        :param str path:
+            requested path (relative or absolute) of the folder to remove.
+        :return: an SFTP error code `int` like `.SFTP_OK`.
         """
         return SFTP_OP_UNSUPPORTED
 
     def chattr(self, path, attr):
         """
-        Change the attributes of a file.  The C{attr} object will contain
+        Change the attributes of a file.  The ``attr`` object will contain
         only those fields provided by the client in its request, so you
         should check for the presence of fields before using them.
 
-        @param path: requested path (relative or absolute) of the file to
-            change.
-        @type path: str
-        @param attr: requested attributes to change on the file.
-        @type attr: L{SFTPAttributes}
-        @return: an error code like L{SFTP_OK}.
-        @rtype: int
+        :param str path:
+            requested path (relative or absolute) of the file to change.
+        :param attr:
+            requested attributes to change on the file (an `.SFTPAttributes`
+            object)
+        :return: an error code `int` like `.SFTP_OK`.
         """
         return SFTP_OP_UNSUPPORTED
 
     def canonicalize(self, path):
         """
         Return the canonical form of a path on the server.  For example,
-        if the server's home folder is C{/home/foo}, the path
-        C{"../betty"} would be canonicalized to C{"/home/betty"}.  Note
+        if the server's home folder is ``/home/foo``, the path
+        ``"../betty"`` would be canonicalized to ``"/home/betty"``.  Note
         the obvious security issues: if you're serving files only from a
         specific folder, you probably don't want this method to reveal path
         names outside that folder.
 
-        You may find the python methods in C{os.path} useful, especially
-        C{os.path.normpath} and C{os.path.realpath}.
+        You may find the Python methods in ``os.path`` useful, especially
+        ``os.path.normpath`` and ``os.path.realpath``.
 
-        The default implementation returns C{os.path.normpath('/' + path)}.
+        The default implementation returns ``os.path.normpath('/' + path)``.
         """
         if os.path.isabs(path):
             out = os.path.normpath(path)
@@ -285,26 +274,23 @@ class SFTPServerInterface (object):
         If the specified path doesn't refer to a symbolic link, an error
         should be returned.
         
-        @param path: path (relative or absolute) of the symbolic link.
-        @type path: str
-        @return: the target path of the symbolic link, or an error code like
-            L{SFTP_NO_SUCH_FILE}.
-        @rtype: str I{or error code}
+        :param str path: path (relative or absolute) of the symbolic link.
+        :return:
+            the target `str` path of the symbolic link, or an error code like
+            `.SFTP_NO_SUCH_FILE`.
         """
         return SFTP_OP_UNSUPPORTED
     
     def symlink(self, target_path, path):
         """
-        Create a symbolic link on the server, as new pathname C{path},
-        with C{target_path} as the target of the link.
+        Create a symbolic link on the server, as new pathname ``path``,
+        with ``target_path`` as the target of the link.
         
-        @param target_path: path (relative or absolute) of the target for
-            this new symbolic link.
-        @type target_path: str
-        @param path: path (relative or absolute) of the symbolic link to
-            create.
-        @type path: str
-        @return: an error code like C{SFTP_OK}.
-        @rtype: int
+        :param str target_path:
+            path (relative or absolute) of the target for this new symbolic
+            link.
+        :param str path:
+            path (relative or absolute) of the symbolic link to create.
+        :return: an error code `int` like ``SFTP_OK``.
         """
         return SFTP_OP_UNSUPPORTED
diff --git a/paramiko/ssh_exception.py b/paramiko/ssh_exception.py
index b502b56..b99e42b 100644
--- a/paramiko/ssh_exception.py
+++ b/paramiko/ssh_exception.py
@@ -16,10 +16,6 @@
 # along with Paramiko; if not, write to the Free Software Foundation, Inc.,
 # 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA.
 
-"""
-Exceptions defined by paramiko.
-"""
-
 
 class SSHException (Exception):
     """
@@ -34,7 +30,7 @@ class AuthenticationException (SSHException):
     possible to retry with different credentials.  (Other classes specify more
     specific reasons.)
     
-    @since: 1.6
+    .. versionadded:: 1.6
     """
     pass
     
@@ -52,19 +48,20 @@ class BadAuthenticationType (AuthenticationException):
     the server isn't allowing that type.  (It may only allow public-key, for
     example.)
     
-    @ivar allowed_types: list of allowed authentication types provided by the
-        server (possible values are: C{"none"}, C{"password"}, and
-        C{"publickey"}).
-    @type allowed_types: list
+    :ivar list allowed_types:
+        list of allowed authentication types provided by the server (possible
+        values are: ``"none"``, ``"password"``, and ``"publickey"``).
     
-    @since: 1.1
+    .. versionadded:: 1.1
     """
     allowed_types = []
     
     def __init__(self, explanation, types):
         AuthenticationException.__init__(self, explanation)
         self.allowed_types = types
-     
+        # for unpickling
+        self.args = (explanation, types, )
+
     def __str__(self):
         return SSHException.__str__(self) + ' (allowed_types=%r)' % self.allowed_types
 
@@ -78,50 +75,50 @@ class PartialAuthentication (AuthenticationException):
     def __init__(self, types):
         AuthenticationException.__init__(self, 'partial authentication')
         self.allowed_types = types
+        # for unpickling
+        self.args = (types, )
 
 
 class ChannelException (SSHException):
     """
-    Exception raised when an attempt to open a new L{Channel} fails.
+    Exception raised when an attempt to open a new `.Channel` fails.
     
-    @ivar code: the error code returned by the server
-    @type code: int
+    :ivar int code: the error code returned by the server
     
-    @since: 1.6
+    .. versionadded:: 1.6
     """
     def __init__(self, code, text):
         SSHException.__init__(self, text)
         self.code = code
+        # for unpickling
+        self.args = (code, text, )
 
 
 class BadHostKeyException (SSHException):
     """
     The host key given by the SSH server did not match what we were expecting.
     
-    @ivar hostname: the hostname of the SSH server
-    @type hostname: str
-    @ivar key: the host key presented by the server
-    @type key: L{PKey}
-    @ivar expected_key: the host key expected
-    @type expected_key: L{PKey}
+    :ivar str hostname: the hostname of the SSH server
+    :ivar PKey got_key: the host key presented by the server
+    :ivar PKey expected_key: the host key expected
     
-    @since: 1.6
+    .. versionadded:: 1.6
     """
     def __init__(self, hostname, got_key, expected_key):
         SSHException.__init__(self, 'Host key for server %s does not match!' % hostname)
         self.hostname = hostname
         self.key = got_key
         self.expected_key = expected_key
+        # for unpickling
+        self.args = (hostname, got_key, expected_key, )
 
 
 class ProxyCommandFailure (SSHException):
     """
     The "ProxyCommand" found in the .ssh/config file returned an error.
 
-    @ivar command: The command line that is generating this exception.
-    @type command: str
-    @ivar error: The error captured from the proxy command output.
-    @type error: str
+    :ivar str command: The command line that is generating this exception.
+    :ivar str error: The error captured from the proxy command output.
     """
     def __init__(self, command, error):
         SSHException.__init__(self,
@@ -130,3 +127,5 @@ class ProxyCommandFailure (SSHException):
             )
         )
         self.error = error
+        # for unpickling
+        self.args = (command, error, )
diff --git a/paramiko/transport.py b/paramiko/transport.py
index b536175..406626a 100644
--- a/paramiko/transport.py
+++ b/paramiko/transport.py
@@ -17,23 +17,32 @@
 # 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA.
 
 """
-L{Transport} handles the core SSH2 protocol.
+Core protocol implementation
 """
 
 import os
 import socket
-import string
-import struct
 import sys
 import threading
 import time
 import weakref
+from hashlib import md5, sha1
 
 import paramiko
 from paramiko import util
 from paramiko.auth_handler import AuthHandler
 from paramiko.channel import Channel
-from paramiko.common import *
+from paramiko.common import xffffffff, cMSG_CHANNEL_OPEN, cMSG_IGNORE, \
+    cMSG_GLOBAL_REQUEST, DEBUG, MSG_KEXINIT, MSG_IGNORE, MSG_DISCONNECT, \
+    MSG_DEBUG, ERROR, WARNING, cMSG_UNIMPLEMENTED, INFO, cMSG_KEXINIT, \
+    cMSG_NEWKEYS, MSG_NEWKEYS, cMSG_REQUEST_SUCCESS, cMSG_REQUEST_FAILURE, \
+    CONNECTION_FAILED_CODE, OPEN_FAILED_ADMINISTRATIVELY_PROHIBITED, \
+    OPEN_SUCCEEDED, cMSG_CHANNEL_OPEN_FAILURE, cMSG_CHANNEL_OPEN_SUCCESS, \
+    MSG_GLOBAL_REQUEST, MSG_REQUEST_SUCCESS, MSG_REQUEST_FAILURE, \
+    MSG_CHANNEL_OPEN_SUCCESS, MSG_CHANNEL_OPEN_FAILURE, MSG_CHANNEL_OPEN, \
+    MSG_CHANNEL_SUCCESS, MSG_CHANNEL_FAILURE, MSG_CHANNEL_DATA, \
+    MSG_CHANNEL_EXTENDED_DATA, MSG_CHANNEL_WINDOW_ADJUST, MSG_CHANNEL_REQUEST, \
+    MSG_CHANNEL_EOF, MSG_CHANNEL_CLOSE
 from paramiko.compress import ZlibCompressor, ZlibDecompressor
 from paramiko.dsskey import DSSKey
 from paramiko.kex_gex import KexGex
@@ -41,17 +50,16 @@ from paramiko.kex_group1 import KexGroup1
 from paramiko.message import Message
 from paramiko.packet import Packetizer, NeedRekeyException
 from paramiko.primes import ModulusPack
+from paramiko.py3compat import string_types, long, byte_ord, b
 from paramiko.rsakey import RSAKey
 from paramiko.ecdsakey import ECDSAKey
 from paramiko.server import ServerInterface
 from paramiko.sftp_client import SFTPClient
 from paramiko.ssh_exception import (SSHException, BadAuthenticationType,
-    ChannelException, ProxyCommandFailure)
+                                    ChannelException, ProxyCommandFailure)
 from paramiko.util import retry_on_signal
 
-from Crypto import Random
 from Crypto.Cipher import Blowfish, AES, DES3, ARC4
-from Crypto.Hash import SHA, MD5
 try:
     from Crypto.Util import Counter
 except ImportError:
@@ -60,223 +68,103 @@ except ImportError:
 
 # for thread cleanup
 _active_threads = []
+
 def _join_lingering_threads():
     for thr in _active_threads:
         thr.stop_thread()
+
 import atexit
 atexit.register(_join_lingering_threads)
 
 
-class SecurityOptions (object):
-    """
-    Simple object containing the security preferences of an ssh transport.
-    These are tuples of acceptable ciphers, digests, key types, and key
-    exchange algorithms, listed in order of preference.
-
-    Changing the contents and/or order of these fields affects the underlying
-    L{Transport} (but only if you change them before starting the session).
-    If you try to add an algorithm that paramiko doesn't recognize,
-    C{ValueError} will be raised.  If you try to assign something besides a
-    tuple to one of the fields, C{TypeError} will be raised.
-    """
-    __slots__ = [ 'ciphers', 'digests', 'key_types', 'kex', 'compression', '_transport' ]
-
-    def __init__(self, transport):
-        self._transport = transport
-
-    def __repr__(self):
-        """
-        Returns a string representation of this object, for debugging.
-
-        @rtype: str
-        """
-        return '<paramiko.SecurityOptions for %s>' % repr(self._transport)
-
-    def _get_ciphers(self):
-        return self._transport._preferred_ciphers
-
-    def _get_digests(self):
-        return self._transport._preferred_macs
-
-    def _get_key_types(self):
-        return self._transport._preferred_keys
-
-    def _get_kex(self):
-        return self._transport._preferred_kex
-
-    def _get_compression(self):
-        return self._transport._preferred_compression
-
-    def _set(self, name, orig, x):
-        if type(x) is list:
-            x = tuple(x)
-        if type(x) is not tuple:
-            raise TypeError('expected tuple or list')
-        possible = getattr(self._transport, orig).keys()
-        forbidden = filter(lambda n: n not in possible, x)
-        if len(forbidden) > 0:
-            raise ValueError('unknown cipher')
-        setattr(self._transport, name, x)
-
-    def _set_ciphers(self, x):
-        self._set('_preferred_ciphers', '_cipher_info', x)
-
-    def _set_digests(self, x):
-        self._set('_preferred_macs', '_mac_info', x)
-
-    def _set_key_types(self, x):
-        self._set('_preferred_keys', '_key_info', x)
-
-    def _set_kex(self, x):
-        self._set('_preferred_kex', '_kex_info', x)
-
-    def _set_compression(self, x):
-        self._set('_preferred_compression', '_compression_info', x)
-
-    ciphers = property(_get_ciphers, _set_ciphers, None,
-                       "Symmetric encryption ciphers")
-    digests = property(_get_digests, _set_digests, None,
-                       "Digest (one-way hash) algorithms")
-    key_types = property(_get_key_types, _set_key_types, None,
-                         "Public-key algorithms")
-    kex = property(_get_kex, _set_kex, None, "Key exchange algorithms")
-    compression = property(_get_compression, _set_compression, None,
-                           "Compression algorithms")
-
-
-class ChannelMap (object):
-    def __init__(self):
-        # (id -> Channel)
-        self._map = weakref.WeakValueDictionary()
-        self._lock = threading.Lock()
-
-    def put(self, chanid, chan):
-        self._lock.acquire()
-        try:
-            self._map[chanid] = chan
-        finally:
-            self._lock.release()
-
-    def get(self, chanid):
-        self._lock.acquire()
-        try:
-            return self._map.get(chanid, None)
-        finally:
-            self._lock.release()
-
-    def delete(self, chanid):
-        self._lock.acquire()
-        try:
-            try:
-                del self._map[chanid]
-            except KeyError:
-                pass
-        finally:
-            self._lock.release()
-
-    def values(self):
-        self._lock.acquire()
-        try:
-            return self._map.values()
-        finally:
-            self._lock.release()
-
-    def __len__(self):
-        self._lock.acquire()
-        try:
-            return len(self._map)
-        finally:
-            self._lock.release()
-
-
 class Transport (threading.Thread):
     """
     An SSH Transport attaches to a stream (usually a socket), negotiates an
     encrypted session, authenticates, and then creates stream tunnels, called
-    L{Channel}s, across the session.  Multiple channels can be multiplexed
-    across a single session (and often are, in the case of port forwardings).
+    `channels <.Channel>`, across the session.  Multiple channels can be
+    multiplexed across a single session (and often are, in the case of port
+    forwardings).
     """
-
     _PROTO_ID = '2.0'
-    _CLIENT_ID = 'paramiko_%s' % (paramiko.__version__)
+    _CLIENT_ID = 'paramiko_%s' % paramiko.__version__
 
-    _preferred_ciphers = ( 'aes128-ctr', 'aes256-ctr', 'aes128-cbc', 'blowfish-cbc', 'aes256-cbc', '3des-cbc',
-        'arcfour128', 'arcfour256' )
-    _preferred_macs = ( 'hmac-sha1', 'hmac-md5', 'hmac-sha1-96', 'hmac-md5-96' )
-    _preferred_keys = ( 'ssh-rsa', 'ssh-dss', 'ecdsa-sha2-nistp256' )
-    _preferred_kex = ( 'diffie-hellman-group1-sha1', 'diffie-hellman-group-exchange-sha1' )
-    _preferred_compression = ( 'none', )
+    _preferred_ciphers = ('aes128-ctr', 'aes256-ctr', 'aes128-cbc', 'blowfish-cbc',
+                          'aes256-cbc', '3des-cbc', 'arcfour128', 'arcfour256')
+    _preferred_macs = ('hmac-sha1', 'hmac-md5', 'hmac-sha1-96', 'hmac-md5-96')
+    _preferred_keys = ('ssh-rsa', 'ssh-dss', 'ecdsa-sha2-nistp256')
+    _preferred_kex = ('diffie-hellman-group1-sha1', 'diffie-hellman-group-exchange-sha1')
+    _preferred_compression = ('none',)
 
     _cipher_info = {
-        'aes128-ctr': { 'class': AES, 'mode': AES.MODE_CTR, 'block-size': 16, 'key-size': 16 },
-        'aes256-ctr': { 'class': AES, 'mode': AES.MODE_CTR, 'block-size': 16, 'key-size': 32 },
-        'blowfish-cbc': { 'class': Blowfish, 'mode': Blowfish.MODE_CBC, 'block-size': 8, 'key-size': 16 },
-        'aes128-cbc': { 'class': AES, 'mode': AES.MODE_CBC, 'block-size': 16, 'key-size': 16 },
-        'aes256-cbc': { 'class': AES, 'mode': AES.MODE_CBC, 'block-size': 16, 'key-size': 32 },
-        '3des-cbc': { 'class': DES3, 'mode': DES3.MODE_CBC, 'block-size': 8, 'key-size': 24 },
-        'arcfour128': { 'class': ARC4, 'mode': None, 'block-size': 8, 'key-size': 16 },
-        'arcfour256': { 'class': ARC4, 'mode': None, 'block-size': 8, 'key-size': 32 },
-        }
+        'aes128-ctr': {'class': AES, 'mode': AES.MODE_CTR, 'block-size': 16, 'key-size': 16},
+        'aes256-ctr': {'class': AES, 'mode': AES.MODE_CTR, 'block-size': 16, 'key-size': 32},
+        'blowfish-cbc': {'class': Blowfish, 'mode': Blowfish.MODE_CBC, 'block-size': 8, 'key-size': 16},
+        'aes128-cbc': {'class': AES, 'mode': AES.MODE_CBC, 'block-size': 16, 'key-size': 16},
+        'aes256-cbc': {'class': AES, 'mode': AES.MODE_CBC, 'block-size': 16, 'key-size': 32},
+        '3des-cbc': {'class': DES3, 'mode': DES3.MODE_CBC, 'block-size': 8, 'key-size': 24},
+        'arcfour128': {'class': ARC4, 'mode': None, 'block-size': 8, 'key-size': 16},
+        'arcfour256': {'class': ARC4, 'mode': None, 'block-size': 8, 'key-size': 32},
+    }
 
     _mac_info = {
-        'hmac-sha1': { 'class': SHA, 'size': 20 },
-        'hmac-sha1-96': { 'class': SHA, 'size': 12 },
-        'hmac-md5': { 'class': MD5, 'size': 16 },
-        'hmac-md5-96': { 'class': MD5, 'size': 12 },
-        }
+        'hmac-sha1': {'class': sha1, 'size': 20},
+        'hmac-sha1-96': {'class': sha1, 'size': 12},
+        'hmac-md5': {'class': md5, 'size': 16},
+        'hmac-md5-96': {'class': md5, 'size': 12},
+    }
 
     _key_info = {
         'ssh-rsa': RSAKey,
         'ssh-dss': DSSKey,
         'ecdsa-sha2-nistp256': ECDSAKey,
-        }
+    }
 
     _kex_info = {
         'diffie-hellman-group1-sha1': KexGroup1,
         'diffie-hellman-group-exchange-sha1': KexGex,
-        }
+    }
 
     _compression_info = {
         # zlib@openssh.com is just zlib, but only turned on after a successful
         # authentication.  openssh servers may only offer this type because
         # they've had troubles with security holes in zlib in the past.
-        'zlib@openssh.com': ( ZlibCompressor, ZlibDecompressor ),
-        'zlib': ( ZlibCompressor, ZlibDecompressor ),
-        'none': ( None, None ),
+        'zlib@openssh.com': (ZlibCompressor, ZlibDecompressor),
+        'zlib': (ZlibCompressor, ZlibDecompressor),
+        'none': (None, None),
     }
 
-
     _modulus_pack = None
 
     def __init__(self, sock):
         """
         Create a new SSH session over an existing socket, or socket-like
-        object.  This only creates the Transport object; it doesn't begin the
-        SSH session yet.  Use L{connect} or L{start_client} to begin a client
-        session, or L{start_server} to begin a server session.
+        object.  This only creates the `.Transport` object; it doesn't begin the
+        SSH session yet.  Use `connect` or `start_client` to begin a client
+        session, or `start_server` to begin a server session.
 
         If the object is not actually a socket, it must have the following
         methods:
-            - C{send(str)}: Writes from 1 to C{len(str)} bytes, and
-              returns an int representing the number of bytes written.  Returns
-              0 or raises C{EOFError} if the stream has been closed.
-            - C{recv(int)}: Reads from 1 to C{int} bytes and returns them as a
-              string.  Returns 0 or raises C{EOFError} if the stream has been
-              closed.
-            - C{close()}: Closes the socket.
-            - C{settimeout(n)}: Sets a (float) timeout on I/O operations.
+
+        - ``send(str)``: Writes from 1 to ``len(str)`` bytes, and returns an
+          int representing the number of bytes written.  Returns
+          0 or raises ``EOFError`` if the stream has been closed.
+        - ``recv(int)``: Reads from 1 to ``int`` bytes and returns them as a
+          string.  Returns 0 or raises ``EOFError`` if the stream has been
+          closed.
+        - ``close()``: Closes the socket.
+        - ``settimeout(n)``: Sets a (float) timeout on I/O operations.
 
         For ease of use, you may also pass in an address (as a tuple) or a host
-        string as the C{sock} argument.  (A host string is a hostname with an
-        optional port (separated by C{":"}) which will be converted into a
-        tuple of C{(hostname, port)}.)  A socket will be connected to this
-        address and used for communication.  Exceptions from the C{socket} call
-        may be thrown in this case.
+        string as the ``sock`` argument.  (A host string is a hostname with an
+        optional port (separated by ``":"``) which will be converted into a
+        tuple of ``(hostname, port)``.)  A socket will be connected to this
+        address and used for communication.  Exceptions from the ``socket``
+        call may be thrown in this case.
 
-        @param sock: a socket or socket-like object to create the session over.
-        @type sock: socket
+        :param socket sock:
+            a socket or socket-like object to create the session over.
         """
-        if isinstance(sock, (str, unicode)):
+        if isinstance(sock, string_types):
             # convert "host:port" into (host, port)
             hl = sock.split(':', 1)
             if len(hl) == 1:
@@ -294,7 +182,7 @@ class Transport (threading.Thread):
                     sock = socket.socket(af, socket.SOCK_STREAM)
                     try:
                         retry_on_signal(lambda: sock.connect((hostname, port)))
-                    except socket.error, e:
+                    except socket.error as e:
                         reason = str(e)
                     else:
                         break
@@ -304,7 +192,6 @@ class Transport (threading.Thread):
         # okay, normal socket-ish flow here...
         threading.Thread.__init__(self)
         self.setDaemon(True)
-        self.rng = rng
         self.sock = sock
         # Python < 2.3 doesn't have the settimeout method - RogerB
         try:
@@ -341,8 +228,8 @@ class Transport (threading.Thread):
 
         # tracking open channels
         self._channels = ChannelMap()
-        self.channel_events = { }       # (id -> Event)
-        self.channels_seen = { }        # (id -> True)
+        self.channel_events = {}       # (id -> Event)
+        self.channels_seen = {}        # (id -> True)
         self._channel_counter = 1
         self.window_size = 65536
         self.max_packet_size = 34816
@@ -365,18 +252,16 @@ class Transport (threading.Thread):
         # server mode:
         self.server_mode = False
         self.server_object = None
-        self.server_key_dict = { }
-        self.server_accepts = [ ]
+        self.server_key_dict = {}
+        self.server_accepts = []
         self.server_accept_cv = threading.Condition(self.lock)
-        self.subsystem_table = { }
+        self.subsystem_table = {}
 
     def __repr__(self):
         """
         Returns a string representation of this object, for debugging.
-
-        @rtype: str
         """
-        out = '<paramiko.Transport at %s' % hex(long(id(self)) & 0xffffffffL)
+        out = '<paramiko.Transport at %s' % hex(long(id(self)) & xffffffff)
         if not self.active:
             out += ' (unconnected)'
         else:
@@ -400,51 +285,47 @@ class Transport (threading.Thread):
         use the connection (without corrupting the session).  Use this method
         to clean up a Transport object without disrupting the other process.
 
-        @since: 1.5.3
+        .. versionadded:: 1.5.3
         """
         self.close()
 
     def get_security_options(self):
         """
-        Return a L{SecurityOptions} object which can be used to tweak the
-        encryption algorithms this transport will permit, and the order of
-        preference for them.
-
-        @return: an object that can be used to change the preferred algorithms
-            for encryption, digest (hash), public key, and key exchange.
-        @rtype: L{SecurityOptions}
+        Return a `.SecurityOptions` object which can be used to tweak the
+        encryption algorithms this transport will permit (for encryption,
+        digest/hash operations, public keys, and key exchanges) and the order
+        of preference for them.
         """
         return SecurityOptions(self)
 
     def start_client(self, event=None):
         """
         Negotiate a new SSH2 session as a client.  This is the first step after
-        creating a new L{Transport}.  A separate thread is created for protocol
+        creating a new `.Transport`.  A separate thread is created for protocol
         negotiation.
 
         If an event is passed in, this method returns immediately.  When
-        negotiation is done (successful or not), the given C{Event} will
-        be triggered.  On failure, L{is_active} will return C{False}.
+        negotiation is done (successful or not), the given ``Event`` will
+        be triggered.  On failure, `is_active` will return ``False``.
 
-        (Since 1.4) If C{event} is C{None}, this method will not return until
+        (Since 1.4) If ``event`` is ``None``, this method will not return until
         negotation is done.  On success, the method returns normally.
         Otherwise an SSHException is raised.
 
         After a successful negotiation, you will usually want to authenticate,
-        calling L{auth_password <Transport.auth_password>} or
-        L{auth_publickey <Transport.auth_publickey>}.
+        calling `auth_password <Transport.auth_password>` or
+        `auth_publickey <Transport.auth_publickey>`.
 
-        @note: L{connect} is a simpler method for connecting as a client.
+        .. note:: `connect` is a simpler method for connecting as a client.
 
-        @note: After calling this method (or L{start_server} or L{connect}),
+        .. note:: After calling this method (or `start_server` or `connect`),
             you should no longer directly read from or write to the original
             socket object.
 
-        @param event: an event to trigger when negotiation is complete
-            (optional)
-        @type event: threading.Event
+        :param .threading.Event event:
+            an event to trigger when negotiation is complete (optional)
 
-        @raise SSHException: if negotiation fails (and no C{event} was passed
+        :raises SSHException: if negotiation fails (and no ``event`` was passed
             in)
         """
         self.active = True
@@ -457,7 +338,6 @@ class Transport (threading.Thread):
         # synchronous, wait for a result
         self.completion_event = event = threading.Event()
         self.start()
-        Random.atfork()
         while True:
             event.wait(0.1)
             if not self.active:
@@ -471,41 +351,42 @@ class Transport (threading.Thread):
     def start_server(self, event=None, server=None):
         """
         Negotiate a new SSH2 session as a server.  This is the first step after
-        creating a new L{Transport} and setting up your server host key(s).  A
+        creating a new `.Transport` and setting up your server host key(s).  A
         separate thread is created for protocol negotiation.
 
         If an event is passed in, this method returns immediately.  When
-        negotiation is done (successful or not), the given C{Event} will
-        be triggered.  On failure, L{is_active} will return C{False}.
+        negotiation is done (successful or not), the given ``Event`` will
+        be triggered.  On failure, `is_active` will return ``False``.
 
-        (Since 1.4) If C{event} is C{None}, this method will not return until
+        (Since 1.4) If ``event`` is ``None``, this method will not return until
         negotation is done.  On success, the method returns normally.
         Otherwise an SSHException is raised.
 
         After a successful negotiation, the client will need to authenticate.
-        Override the methods
-        L{get_allowed_auths <ServerInterface.get_allowed_auths>},
-        L{check_auth_none <ServerInterface.check_auth_none>},
-        L{check_auth_password <ServerInterface.check_auth_password>}, and
-        L{check_auth_publickey <ServerInterface.check_auth_publickey>} in the
-        given C{server} object to control the authentication process.
-
-        After a successful authentication, the client should request to open
-        a channel.  Override
-        L{check_channel_request <ServerInterface.check_channel_request>} in the
-        given C{server} object to allow channels to be opened.
-
-        @note: After calling this method (or L{start_client} or L{connect}),
-            you should no longer directly read from or write to the original
-            socket object.
-
-        @param event: an event to trigger when negotiation is complete.
-        @type event: threading.Event
-        @param server: an object used to perform authentication and create
-            L{Channel}s.
-        @type server: L{server.ServerInterface}
-
-        @raise SSHException: if negotiation fails (and no C{event} was passed
+        Override the methods `get_allowed_auths
+        <.ServerInterface.get_allowed_auths>`, `check_auth_none
+        <.ServerInterface.check_auth_none>`, `check_auth_password
+        <.ServerInterface.check_auth_password>`, and `check_auth_publickey
+        <.ServerInterface.check_auth_publickey>` in the given ``server`` object
+        to control the authentication process.
+
+        After a successful authentication, the client should request to open a
+        channel.  Override `check_channel_request
+        <.ServerInterface.check_channel_request>` in the given ``server``
+        object to allow channels to be opened.
+
+        .. note::
+            After calling this method (or `start_client` or `connect`), you
+            should no longer directly read from or write to the original socket
+            object.
+
+        :param .threading.Event event:
+            an event to trigger when negotiation is complete.
+        :param .ServerInterface server:
+            an object used to perform authentication and create `channels
+            <.Channel>`
+
+        :raises SSHException: if negotiation fails (and no ``event`` was passed
             in)
         """
         if server is None:
@@ -541,9 +422,8 @@ class Transport (threading.Thread):
         key info, not just the public half.  Only one key of each type (RSA or
         DSS) is kept.
 
-        @param key: the host key to add, usually an L{RSAKey <rsakey.RSAKey>} or
-            L{DSSKey <dsskey.DSSKey>}.
-        @type key: L{PKey <pkey.PKey>}
+        :param .PKey key:
+            the host key to add, usually an `.RSAKey` or `.DSSKey`.
         """
         self.server_key_dict[key.get_name()] = key
 
@@ -551,15 +431,16 @@ class Transport (threading.Thread):
         """
         Return the active host key, in server mode.  After negotiating with the
         client, this method will return the negotiated host key.  If only one
-        type of host key was set with L{add_server_key}, that's the only key
+        type of host key was set with `add_server_key`, that's the only key
         that will ever be returned.  But in cases where you have set more than
         one type of host key (for example, an RSA key and a DSS key), the key
         type will be negotiated by the client, and this method will return the
         key of the type agreed on.  If the host key has not been negotiated
-        yet, C{None} is returned.  In client mode, the behavior is undefined.
+        yet, ``None`` is returned.  In client mode, the behavior is undefined.
 
-        @return: host key of the type negotiated by the client, or C{None}.
-        @rtype: L{PKey <pkey.PKey>}
+        :return:
+            host key (`.PKey`) of the type negotiated by the client, or
+            ``None``.
         """
         try:
             return self.server_key_dict[self.host_key_type]
@@ -569,7 +450,7 @@ class Transport (threading.Thread):
 
     def load_server_moduli(filename=None):
         """
-        I{(optional)}
+        (optional)
         Load a file of prime moduli for use in doing group-exchange key
         negotiation in server mode.  It's a rather obscure option and can be
         safely ignored.
@@ -578,24 +459,23 @@ class Transport (threading.Thread):
         negotiation, which asks the server to send a random prime number that
         fits certain criteria.  These primes are pretty difficult to compute,
         so they can't be generated on demand.  But many systems contain a file
-        of suitable primes (usually named something like C{/etc/ssh/moduli}).
-        If you call C{load_server_moduli} and it returns C{True}, then this
+        of suitable primes (usually named something like ``/etc/ssh/moduli``).
+        If you call `load_server_moduli` and it returns ``True``, then this
         file of primes has been loaded and we will support "group-exchange" in
         server mode.  Otherwise server mode will just claim that it doesn't
         support that method of key negotiation.
 
-        @param filename: optional path to the moduli file, if you happen to
-            know that it's not in a standard location.
-        @type filename: str
-        @return: True if a moduli file was successfully loaded; False
-            otherwise.
-        @rtype: bool
+        :param str filename:
+            optional path to the moduli file, if you happen to know that it's
+            not in a standard location.
+        :return:
+            True if a moduli file was successfully loaded; False otherwise.
 
-        @note: This has no effect when used in client mode.
+        .. note:: This has no effect when used in client mode.
         """
-        Transport._modulus_pack = ModulusPack(rng)
+        Transport._modulus_pack = ModulusPack()
         # places to look for the openssh "moduli" file
-        file_list = [ '/etc/ssh/moduli', '/usr/local/etc/moduli' ]
+        file_list = ['/etc/ssh/moduli', '/usr/local/etc/moduli']
         if filename is not None:
             file_list.insert(0, filename)
         for fn in file_list:
@@ -616,7 +496,7 @@ class Transport (threading.Thread):
         if not self.active:
             return
         self.stop_thread()
-        for chan in self._channels.values():
+        for chan in list(self._channels.values()):
             chan._unlink()
         self.sock.close()
 
@@ -624,15 +504,14 @@ class Transport (threading.Thread):
         """
         Return the host key of the server (in client mode).
 
-        @note: Previously this call returned a tuple of (key type, key string).
-            You can get the same effect by calling
-            L{PKey.get_name <pkey.PKey.get_name>} for the key type, and
-            C{str(key)} for the key string.
+        .. note::
+            Previously this call returned a tuple of ``(key type, key
+            string)``. You can get the same effect by calling `.PKey.get_name`
+            for the key type, and ``str(key)`` for the key string.
 
-        @raise SSHException: if no session is currently active.
+        :raises SSHException: if no session is currently active.
 
-        @return: public key of the remote server
-        @rtype: L{PKey <pkey.PKey>}
+        :return: public key (`.PKey`) of the remote server
         """
         if (not self.active) or (not self.initial_kex_done):
             raise SSHException('No existing session')
@@ -642,37 +521,36 @@ class Transport (threading.Thread):
         """
         Return true if this session is active (open).
 
-        @return: True if the session is still active (open); False if the
-            session is closed
-        @rtype: bool
+        :return:
+            True if the session is still active (open); False if the session is
+            closed
         """
         return self.active
 
     def open_session(self):
         """
-        Request a new channel to the server, of type C{"session"}.  This
-        is just an alias for C{open_channel('session')}.
+        Request a new channel to the server, of type ``"session"``.  This is
+        just an alias for calling `open_channel` with an argument of
+        ``"session"``.
 
-        @return: a new L{Channel}
-        @rtype: L{Channel}
+        :return: a new `.Channel`
 
-        @raise SSHException: if the request is rejected or the session ends
+        :raises SSHException: if the request is rejected or the session ends
             prematurely
         """
         return self.open_channel('session')
 
     def open_x11_channel(self, src_addr=None):
         """
-        Request a new channel to the client, of type C{"x11"}.  This
-        is just an alias for C{open_channel('x11', src_addr=src_addr)}.
+        Request a new channel to the client, of type ``"x11"``.  This
+        is just an alias for ``open_channel('x11', src_addr=src_addr)``.
 
-        @param src_addr: the source address of the x11 server (port is the
+        :param tuple src_addr:
+            the source address (``(str, int)``) of the x11 server (port is the
             x11 port, ie. 6010)
-        @type src_addr: (str, int)
-        @return: a new L{Channel}
-        @rtype: L{Channel}
+        :return: a new `.Channel`
 
-        @raise SSHException: if the request is rejected or the session ends
+        :raises SSHException: if the request is rejected or the session ends
             prematurely
         """
         return self.open_channel('x11', src_addr=src_addr)
@@ -680,51 +558,47 @@ class Transport (threading.Thread):
     def open_forward_agent_channel(self):
         """
         Request a new channel to the client, of type
-        C{"auth-agent@openssh.com"}.
+        ``"auth-agent@openssh.com"``.
 
-        This is just an alias for C{open_channel('auth-agent@openssh.com')}.
-        @return: a new L{Channel}
-        @rtype: L{Channel}
+        This is just an alias for ``open_channel('auth-agent@openssh.com')``.
 
-        @raise SSHException: if the request is rejected or the session ends
-            prematurely
+        :return: a new `.Channel`
+
+        :raises SSHException:
+            if the request is rejected or the session ends prematurely
         """
         return self.open_channel('auth-agent@openssh.com')
 
-    def open_forwarded_tcpip_channel(self, (src_addr, src_port), (dest_addr, dest_port)):
+    def open_forwarded_tcpip_channel(self, src_addr, dest_addr):
         """
-        Request a new channel back to the client, of type C{"forwarded-tcpip"}.
+        Request a new channel back to the client, of type ``"forwarded-tcpip"``.
         This is used after a client has requested port forwarding, for sending
         incoming connections back to the client.
 
-        @param src_addr: originator's address
-        @param src_port: originator's port
-        @param dest_addr: local (server) connected address
-        @param dest_port: local (server) connected port
+        :param src_addr: originator's address
+        :param dest_addr: local (server) connected address
         """
-        return self.open_channel('forwarded-tcpip', (dest_addr, dest_port), (src_addr, src_port))
+        return self.open_channel('forwarded-tcpip', dest_addr, src_addr)
 
     def open_channel(self, kind, dest_addr=None, src_addr=None):
         """
-        Request a new channel to the server.  L{Channel}s are socket-like
-        objects used for the actual transfer of data across the session.
-        You may only request a channel after negotiating encryption (using
-        L{connect} or L{start_client}) and authenticating.
-
-        @param kind: the kind of channel requested (usually C{"session"},
-            C{"forwarded-tcpip"}, C{"direct-tcpip"}, or C{"x11"})
-        @type kind: str
-        @param dest_addr: the destination address of this port forwarding,
-            if C{kind} is C{"forwarded-tcpip"} or C{"direct-tcpip"} (ignored
-            for other channel types)
-        @type dest_addr: (str, int)
-        @param src_addr: the source address of this port forwarding, if
-            C{kind} is C{"forwarded-tcpip"}, C{"direct-tcpip"}, or C{"x11"}
-        @type src_addr: (str, int)
-        @return: a new L{Channel} on success
-        @rtype: L{Channel}
-
-        @raise SSHException: if the request is rejected or the session ends
+        Request a new channel to the server. `Channels <.Channel>` are
+        socket-like objects used for the actual transfer of data across the
+        session. You may only request a channel after negotiating encryption
+        (using `connect` or `start_client`) and authenticating.
+
+        :param str kind:
+            the kind of channel requested (usually ``"session"``,
+            ``"forwarded-tcpip"``, ``"direct-tcpip"``, or ``"x11"``)
+        :param tuple dest_addr:
+            the destination address (address + port tuple) of this port
+            forwarding, if ``kind`` is ``"forwarded-tcpip"`` or
+            ``"direct-tcpip"`` (ignored for other channel types)
+        :param src_addr: the source address of this port forwarding, if
+            ``kind`` is ``"forwarded-tcpip"``, ``"direct-tcpip"``, or ``"x11"``
+        :return: a new `.Channel` on success
+
+        :raises SSHException: if the request is rejected or the session ends
             prematurely
         """
         if not self.active:
@@ -733,7 +607,7 @@ class Transport (threading.Thread):
         try:
             chanid = self._next_channel()
             m = Message()
-            m.add_byte(chr(MSG_CHANNEL_OPEN))
+            m.add_byte(cMSG_CHANNEL_OPEN)
             m.add_string(kind)
             m.add_int(chanid)
             m.add_int(self.window_size)
@@ -756,7 +630,7 @@ class Transport (threading.Thread):
             self.lock.release()
         self._send_user_message(m)
         while True:
-            event.wait(0.1);
+            event.wait(0.1)
             if not self.active:
                 e = self.get_exception()
                 if e is None:
@@ -782,28 +656,25 @@ class Transport (threading.Thread):
 
             handler(channel, (origin_addr, origin_port), (server_addr, server_port))
 
-        where C{server_addr} and C{server_port} are the address and port that
+        where ``server_addr`` and ``server_port`` are the address and port that
         the server was listening on.
 
         If no handler is set, the default behavior is to send new incoming
         forwarded connections into the accept queue, to be picked up via
-        L{accept}.
+        `accept`.
 
-        @param address: the address to bind when forwarding
-        @type address: str
-        @param port: the port to forward, or 0 to ask the server to allocate
-            any port
-        @type port: int
-        @param handler: optional handler for incoming forwarded connections
-        @type handler: function(Channel, (str, int), (str, int))
-        @return: the port # allocated by the server
-        @rtype: int
+        :param str address: the address to bind when forwarding
+        :param int port:
+            the port to forward, or 0 to ask the server to allocate any port
+        :param callable handler:
+            optional handler for incoming forwarded connections, of the form
+            ``func(Channel, (str, int), (str, int))``.
+        :return: the port number (`int`) allocated by the server
 
-        @raise SSHException: if the server refused the TCP forward request
+        :raises SSHException: if the server refused the TCP forward request
         """
         if not self.active:
             raise SSHException('SSH session not active')
-        address = str(address)
         port = int(port)
         response = self.global_request('tcpip-forward', (address, port), wait=True)
         if response is None:
@@ -811,7 +682,9 @@ class Transport (threading.Thread):
         if port == 0:
             port = response.get_int()
         if handler is None:
-            def default_handler(channel, (src_addr, src_port), (dest_addr, dest_port)):
+            def default_handler(channel, src_addr, dest_addr_port):
+                #src_addr, src_port = src_addr_port
+                #dest_addr, dest_port = dest_addr_port
                 self._queue_incoming_channel(channel)
             handler = default_handler
         self._tcp_handler = handler
@@ -823,10 +696,8 @@ class Transport (threading.Thread):
         connections to the given address & port will be forwarded across this
         ssh connection.
 
-        @param address: the address to stop forwarding
-        @type address: str
-        @param port: the port to stop forwarding
-        @type port: int
+        :param str address: the address to stop forwarding
+        :param int port: the port to stop forwarding
         """
         if not self.active:
             return
@@ -835,32 +706,32 @@ class Transport (threading.Thread):
 
     def open_sftp_client(self):
         """
-        Create an SFTP client channel from an open transport.  On success,
-        an SFTP session will be opened with the remote host, and a new
-        SFTPClient object will be returned.
+        Create an SFTP client channel from an open transport.  On success, an
+        SFTP session will be opened with the remote host, and a new
+        `.SFTPClient` object will be returned.
 
-        @return: a new L{SFTPClient} object, referring to an sftp session
-            (channel) across this transport
-        @rtype: L{SFTPClient}
+        :return:
+            a new `.SFTPClient` referring to an sftp session (channel) across
+            this transport
         """
         return SFTPClient.from_transport(self)
 
-    def send_ignore(self, bytes=None):
+    def send_ignore(self, byte_count=None):
         """
         Send a junk packet across the encrypted link.  This is sometimes used
         to add "noise" to a connection to confuse would-be attackers.  It can
         also be used as a keep-alive for long lived connections traversing
         firewalls.
 
-        @param bytes: the number of random bytes to send in the payload of the
-            ignored packet -- defaults to a random number from 10 to 41.
-        @type bytes: int
+        :param int byte_count:
+            the number of random bytes to send in the payload of the ignored
+            packet -- defaults to a random number from 10 to 41.
         """
         m = Message()
-        m.add_byte(chr(MSG_IGNORE))
-        if bytes is None:
-            bytes = (ord(rng.read(1)) % 32) + 10
-        m.add_bytes(rng.read(bytes))
+        m.add_byte(cMSG_IGNORE)
+        if byte_count is None:
+            byte_count = (byte_ord(os.urandom(1)) % 32) + 10
+        m.add_bytes(os.urandom(byte_count))
         self._send_user_message(m)
 
     def renegotiate_keys(self):
@@ -872,7 +743,7 @@ class Transport (threading.Thread):
         traffic both ways as the two sides swap keys and do computations.  This
         method returns when the session has switched to new keys.
 
-        @raise SSHException: if the key renegotiation failed (which causes the
+        :raises SSHException: if the key renegotiation failed (which causes the
             session to end)
         """
         self.completion_event = threading.Event()
@@ -891,39 +762,38 @@ class Transport (threading.Thread):
     def set_keepalive(self, interval):
         """
         Turn on/off keepalive packets (default is off).  If this is set, after
-        C{interval} seconds without sending any data over the connection, a
+        ``interval`` seconds without sending any data over the connection, a
         "keepalive" packet will be sent (and ignored by the remote host).  This
         can be useful to keep connections alive over a NAT, for example.
 
-        @param interval: seconds to wait before sending a keepalive packet (or
+        :param int interval:
+            seconds to wait before sending a keepalive packet (or
             0 to disable keepalives).
-        @type interval: int
         """
         self.packetizer.set_keepalive(interval,
-            lambda x=weakref.proxy(self): x.global_request('keepalive@lag.net', wait=False))
+                                      lambda x=weakref.proxy(self): x.global_request('keepalive@lag.net', wait=False))
 
     def global_request(self, kind, data=None, wait=True):
         """
         Make a global request to the remote host.  These are normally
         extensions to the SSH2 protocol.
 
-        @param kind: name of the request.
-        @type kind: str
-        @param data: an optional tuple containing additional data to attach
-            to the request.
-        @type data: tuple
-        @param wait: C{True} if this method should not return until a response
-            is received; C{False} otherwise.
-        @type wait: bool
-        @return: a L{Message} containing possible additional data if the
-            request was successful (or an empty L{Message} if C{wait} was
-            C{False}); C{None} if the request was denied.
-        @rtype: L{Message}
+        :param str kind: name of the request.
+        :param tuple data:
+            an optional tuple containing additional data to attach to the
+            request.
+        :param bool wait:
+            ``True`` if this method should not return until a response is
+            received; ``False`` otherwise.
+        :return:
+            a `.Message` containing possible additional data if the request was
+            successful (or an empty `.Message` if ``wait`` was ``False``);
+            ``None`` if the request was denied.
         """
         if wait:
             self.completion_event = threading.Event()
         m = Message()
-        m.add_byte(chr(MSG_GLOBAL_REQUEST))
+        m.add_byte(cMSG_GLOBAL_REQUEST)
         m.add_string(kind)
         m.add_boolean(wait)
         if data is not None:
@@ -943,14 +813,12 @@ class Transport (threading.Thread):
     def accept(self, timeout=None):
         """
         Return the next channel opened by the client over this transport, in
-        server mode.  If no channel is opened before the given timeout, C{None}
+        server mode.  If no channel is opened before the given timeout, ``None``
         is returned.
 
-        @param timeout: seconds to wait for a channel, or C{None} to wait
-            forever
-        @type timeout: int
-        @return: a new Channel opened by the client
-        @rtype: L{Channel}
+        :param int timeout:
+            seconds to wait for a channel, or ``None`` to wait forever
+        :return: a new `.Channel` opened by the client
         """
         self.lock.acquire()
         try:
@@ -971,48 +839,48 @@ class Transport (threading.Thread):
         """
         Negotiate an SSH2 session, and optionally verify the server's host key
         and authenticate using a password or private key.  This is a shortcut
-        for L{start_client}, L{get_remote_server_key}, and
-        L{Transport.auth_password} or L{Transport.auth_publickey}.  Use those
+        for `start_client`, `get_remote_server_key`, and
+        `Transport.auth_password` or `Transport.auth_publickey`.  Use those
         methods if you want more control.
 
         You can use this method immediately after creating a Transport to
         negotiate encryption with a server.  If it fails, an exception will be
         thrown.  On success, the method will return cleanly, and an encrypted
-        session exists.  You may immediately call L{open_channel} or
-        L{open_session} to get a L{Channel} object, which is used for data
+        session exists.  You may immediately call `open_channel` or
+        `open_session` to get a `.Channel` object, which is used for data
         transfer.
 
-        @note: If you fail to supply a password or private key, this method may
-        succeed, but a subsequent L{open_channel} or L{open_session} call may
-        fail because you haven't authenticated yet.
-
-        @param hostkey: the host key expected from the server, or C{None} if
-            you don't want to do host key verification.
-        @type hostkey: L{PKey<pkey.PKey>}
-        @param username: the username to authenticate as.
-        @type username: str
-        @param password: a password to use for authentication, if you want to
-            use password authentication; otherwise C{None}.
-        @type password: str
-        @param pkey: a private key to use for authentication, if you want to
-            use private key authentication; otherwise C{None}.
-        @type pkey: L{PKey<pkey.PKey>}
-
-        @raise SSHException: if the SSH2 negotiation fails, the host key
+        .. note::
+            If you fail to supply a password or private key, this method may
+            succeed, but a subsequent `open_channel` or `open_session` call may
+            fail because you haven't authenticated yet.
+
+        :param .PKey hostkey:
+            the host key expected from the server, or ``None`` if you don't
+            want to do host key verification.
+        :param str username: the username to authenticate as.
+        :param str password:
+            a password to use for authentication, if you want to use password
+            authentication; otherwise ``None``.
+        :param .PKey pkey:
+            a private key to use for authentication, if you want to use private
+            key authentication; otherwise ``None``.
+
+        :raises SSHException: if the SSH2 negotiation fails, the host key
             supplied by the server is incorrect, or authentication fails.
         """
         if hostkey is not None:
-            self._preferred_keys = [ hostkey.get_name() ]
+            self._preferred_keys = [hostkey.get_name()]
 
         self.start_client()
 
         # check host key if we were given one
-        if (hostkey is not None):
+        if hostkey is not None:
             key = self.get_remote_server_key()
-            if (key.get_name() != hostkey.get_name()) or (str(key) != str(hostkey)):
+            if (key.get_name() != hostkey.get_name()) or (key.asbytes() != hostkey.asbytes()):
                 self._log(DEBUG, 'Bad host key from server')
-                self._log(DEBUG, 'Expected: %s: %s' % (hostkey.get_name(), repr(str(hostkey))))
-                self._log(DEBUG, 'Got     : %s: %s' % (key.get_name(), repr(str(key))))
+                self._log(DEBUG, 'Expected: %s: %s' % (hostkey.get_name(), repr(hostkey.asbytes())))
+                self._log(DEBUG, 'Got     : %s: %s' % (key.get_name(), repr(key.asbytes())))
                 raise SSHException('Bad host key from server')
             self._log(DEBUG, 'Host key verified (%s)' % hostkey.get_name())
 
@@ -1030,13 +898,13 @@ class Transport (threading.Thread):
         """
         Return any exception that happened during the last server request.
         This can be used to fetch more specific error information after using
-        calls like L{start_client}.  The exception (if any) is cleared after
+        calls like `start_client`.  The exception (if any) is cleared after
         this call.
 
-        @return: an exception, or C{None} if there is no stored exception.
-        @rtype: Exception
+        :return:
+            an exception, or ``None`` if there is no stored exception.
 
-        @since: 1.1
+        .. versionadded:: 1.1
         """
         self.lock.acquire()
         try:
@@ -1050,17 +918,15 @@ class Transport (threading.Thread):
         """
         Set the handler class for a subsystem in server mode.  If a request
         for this subsystem is made on an open ssh channel later, this handler
-        will be constructed and called -- see L{SubsystemHandler} for more
+        will be constructed and called -- see `.SubsystemHandler` for more
         detailed documentation.
 
         Any extra parameters (including keyword arguments) are saved and
-        passed to the L{SubsystemHandler} constructor later.
+        passed to the `.SubsystemHandler` constructor later.
 
-        @param name: name of the subsystem.
-        @type name: str
-        @param handler: subclass of L{SubsystemHandler} that handles this
-            subsystem.
-        @type handler: class
+        :param str name: name of the subsystem.
+        :param class handler:
+            subclass of `.SubsystemHandler` that handles this subsystem.
         """
         try:
             self.lock.acquire()
@@ -1072,10 +938,10 @@ class Transport (threading.Thread):
         """
         Return true if this session is active and authenticated.
 
-        @return: True if the session is still open and has been authenticated
+        :return:
+            True if the session is still open and has been authenticated
             successfully; False if authentication failed and/or the session is
             closed.
-        @rtype: bool
         """
         return self.active and (self.auth_handler is not None) and self.auth_handler.is_authenticated()
 
@@ -1083,34 +949,44 @@ class Transport (threading.Thread):
         """
         Return the username this connection is authenticated for.  If the
         session is not authenticated (or authentication failed), this method
-        returns C{None}.
+        returns ``None``.
 
-        @return: username that was authenticated, or C{None}.
-        @rtype: string
+        :return: username that was authenticated (a `str`), or ``None``.
         """
         if not self.active or (self.auth_handler is None):
             return None
         return self.auth_handler.get_username()
 
+    def get_banner(self):
+        """
+        Return the banner supplied by the server upon connect. If no banner is
+        supplied, this method returns C{None}.
+
+        @return: server supplied banner, or C{None}.
+        @rtype: string
+        """
+        if not self.active or (self.auth_handler is None):
+            return None
+        return self.auth_handler.banner
+
     def auth_none(self, username):
         """
         Try to authenticate to the server using no authentication at all.
         This will almost always fail.  It may be useful for determining the
         list of authentication types supported by the server, by catching the
-        L{BadAuthenticationType} exception raised.
+        `.BadAuthenticationType` exception raised.
 
-        @param username: the username to authenticate as
-        @type username: string
-        @return: list of auth types permissible for the next stage of
+        :param str username: the username to authenticate as
+        :return:
+            `list` of auth types permissible for the next stage of
             authentication (normally empty)
-        @rtype: list
 
-        @raise BadAuthenticationType: if "none" authentication isn't allowed
+        :raises BadAuthenticationType: if "none" authentication isn't allowed
             by the server for this user
-        @raise SSHException: if the authentication failed due to a network
+        :raises SSHException: if the authentication failed due to a network
             error
 
-        @since: 1.5
+        .. versionadded:: 1.5
         """
         if (not self.active) or (not self.initial_kex_done):
             raise SSHException('No existing session')
@@ -1124,16 +1000,16 @@ class Transport (threading.Thread):
         Authenticate to the server using a password.  The username and password
         are sent over an encrypted link.
 
-        If an C{event} is passed in, this method will return immediately, and
+        If an ``event`` is passed in, this method will return immediately, and
         the event will be triggered once authentication succeeds or fails.  On
-        success, L{is_authenticated} will return C{True}.  On failure, you may
-        use L{get_exception} to get more detailed error information.
+        success, `is_authenticated` will return ``True``.  On failure, you may
+        use `get_exception` to get more detailed error information.
 
         Since 1.1, if no event is passed, this method will block until the
         authentication succeeds or fails.  On failure, an exception is raised.
         Otherwise, the method simply returns.
 
-        Since 1.5, if no event is passed and C{fallback} is C{True} (the
+        Since 1.5, if no event is passed and ``fallback`` is ``True`` (the
         default), if the server doesn't support plain password authentication
         but does support so-called "keyboard-interactive" mode, an attempt
         will be made to authenticate using this interactive mode.  If it fails,
@@ -1146,26 +1022,23 @@ class Transport (threading.Thread):
         this method will return a list of auth types permissible for the next
         step.  Otherwise, in the normal case, an empty list is returned.
 
-        @param username: the username to authenticate as
-        @type username: str
-        @param password: the password to authenticate with
-        @type password: str or unicode
-        @param event: an event to trigger when the authentication attempt is
-            complete (whether it was successful or not)
-        @type event: threading.Event
-        @param fallback: C{True} if an attempt at an automated "interactive"
-            password auth should be made if the server doesn't support normal
-            password auth
-        @type fallback: bool
-        @return: list of auth types permissible for the next stage of
+        :param str username: the username to authenticate as
+        :param basestring password: the password to authenticate with
+        :param .threading.Event event:
+            an event to trigger when the authentication attempt is complete
+            (whether it was successful or not)
+        :param bool fallback:
+            ``True`` if an attempt at an automated "interactive" password auth
+            should be made if the server doesn't support normal password auth
+        :return:
+            `list` of auth types permissible for the next stage of
             authentication (normally empty)
-        @rtype: list
 
-        @raise BadAuthenticationType: if password authentication isn't
+        :raises BadAuthenticationType: if password authentication isn't
             allowed by the server for this user (and no event was passed in)
-        @raise AuthenticationException: if the authentication failed (and no
+        :raises AuthenticationException: if the authentication failed (and no
             event was passed in)
-        @raise SSHException: if there was a network error
+        :raises SSHException: if there was a network error
         """
         if (not self.active) or (not self.initial_kex_done):
             # we should never try to send the password unless we're on a secure link
@@ -1181,9 +1054,9 @@ class Transport (threading.Thread):
             return []
         try:
             return self.auth_handler.wait_for_response(my_event)
-        except BadAuthenticationType, x:
+        except BadAuthenticationType as e:
             # if password auth isn't allowed, but keyboard-interactive *is*, try to fudge it
-            if not fallback or ('keyboard-interactive' not in x.allowed_types):
+            if not fallback or ('keyboard-interactive' not in e.allowed_types):
                 raise
             try:
                 def handler(title, instructions, fields):
@@ -1195,22 +1068,21 @@ class Transport (threading.Thread):
                         # to try to fake out automated scripting of the exact
                         # type we're doing here.  *shrug* :)
                         return []
-                    return [ password ]
+                    return [password]
                 return self.auth_interactive(username, handler)
-            except SSHException, ignored:
+            except SSHException:
                 # attempt failed; just raise the original exception
-                raise x
-        return None
+                raise e
 
     def auth_publickey(self, username, key, event=None):
         """
         Authenticate to the server using a private key.  The key is used to
         sign data from the server, so it must include the private part.
 
-        If an C{event} is passed in, this method will return immediately, and
+        If an ``event`` is passed in, this method will return immediately, and
         the event will be triggered once authentication succeeds or fails.  On
-        success, L{is_authenticated} will return C{True}.  On failure, you may
-        use L{get_exception} to get more detailed error information.
+        success, `is_authenticated` will return ``True``.  On failure, you may
+        use `get_exception` to get more detailed error information.
 
         Since 1.1, if no event is passed, this method will block until the
         authentication succeeds or fails.  On failure, an exception is raised.
@@ -1220,22 +1092,20 @@ class Transport (threading.Thread):
         this method will return a list of auth types permissible for the next
         step.  Otherwise, in the normal case, an empty list is returned.
 
-        @param username: the username to authenticate as
-        @type username: string
-        @param key: the private key to authenticate with
-        @type key: L{PKey <pkey.PKey>}
-        @param event: an event to trigger when the authentication attempt is
-            complete (whether it was successful or not)
-        @type event: threading.Event
-        @return: list of auth types permissible for the next stage of
+        :param str username: the username to authenticate as
+        :param .PKey key: the private key to authenticate with
+        :param .threading.Event event:
+            an event to trigger when the authentication attempt is complete
+            (whether it was successful or not)
+        :return:
+            `list` of auth types permissible for the next stage of
             authentication (normally empty)
-        @rtype: list
 
-        @raise BadAuthenticationType: if public-key authentication isn't
+        :raises BadAuthenticationType: if public-key authentication isn't
             allowed by the server for this user (and no event was passed in)
-        @raise AuthenticationException: if the authentication failed (and no
+        :raises AuthenticationException: if the authentication failed (and no
             event was passed in)
-        @raise SSHException: if there was a network error
+        :raises SSHException: if there was a network error
         """
         if (not self.active) or (not self.initial_kex_done):
             # we should never try to authenticate unless we're on a secure link
@@ -1263,15 +1133,15 @@ class Transport (threading.Thread):
         if the server continues to ask questions.
 
         The handler is expected to be a callable that will handle calls of the
-        form: C{handler(title, instructions, prompt_list)}.  The C{title} is
-        meant to be a dialog-window title, and the C{instructions} are user
-        instructions (both are strings).  C{prompt_list} will be a list of
-        prompts, each prompt being a tuple of C{(str, bool)}.  The string is
+        form: ``handler(title, instructions, prompt_list)``.  The ``title`` is
+        meant to be a dialog-window title, and the ``instructions`` are user
+        instructions (both are strings).  ``prompt_list`` will be a list of
+        prompts, each prompt being a tuple of ``(str, bool)``.  The string is
         the prompt and the boolean indicates whether the user text should be
         echoed.
 
         A sample call would thus be:
-        C{handler('title', 'instructions', [('Password:', False)])}.
+        ``handler('title', 'instructions', [('Password:', False)])``.
 
         The handler should return a list or tuple of answers to the server's
         questions.
@@ -1280,22 +1150,19 @@ class Transport (threading.Thread):
         this method will return a list of auth types permissible for the next
         step.  Otherwise, in the normal case, an empty list is returned.
 
-        @param username: the username to authenticate as
-        @type username: string
-        @param handler: a handler for responding to server questions
-        @type handler: callable
-        @param submethods: a string list of desired submethods (optional)
-        @type submethods: str
-        @return: list of auth types permissible for the next stage of
+        :param str username: the username to authenticate as
+        :param callable handler: a handler for responding to server questions
+        :param str submethods: a string list of desired submethods (optional)
+        :return:
+            `list` of auth types permissible for the next stage of
             authentication (normally empty).
-        @rtype: list
 
-        @raise BadAuthenticationType: if public-key authentication isn't
+        :raises BadAuthenticationType: if public-key authentication isn't
             allowed by the server for this user
-        @raise AuthenticationException: if the authentication failed
-        @raise SSHException: if there was a network error
+        :raises AuthenticationException: if the authentication failed
+        :raises SSHException: if there was a network error
 
-        @since: 1.5
+        .. versionadded:: 1.5
         """
         if (not self.active) or (not self.initial_kex_done):
             # we should never try to authenticate unless we're on a secure link
@@ -1308,14 +1175,13 @@ class Transport (threading.Thread):
     def set_log_channel(self, name):
         """
         Set the channel for this transport's logging.  The default is
-        C{"paramiko.transport"} but it can be set to anything you want.
-        (See the C{logging} module for more info.)  SSH Channels will log
-        to a sub-channel of the one specified.
+        ``"paramiko.transport"`` but it can be set to anything you want. (See
+        the `.logging` module for more info.)  SSH Channels will log to a
+        sub-channel of the one specified.
 
-        @param name: new channel name for logging
-        @type name: str
+        :param str name: new channel name for logging
 
-        @since: 1.1
+        .. versionadded:: 1.1
         """
         self.log_name = name
         self.logger = util.get_logger(name)
@@ -1325,10 +1191,9 @@ class Transport (threading.Thread):
         """
         Return the channel name used for this transport's logging.
 
-        @return: channel name.
-        @rtype: str
+        :return: channel name as a `str`
 
-        @since: 1.2
+        .. versionadded:: 1.2
         """
         return self.log_name
 
@@ -1338,54 +1203,54 @@ class Transport (threading.Thread):
         the logs.  Normally you would want this off (which is the default),
         but if you are debugging something, it may be useful.
 
-        @param hexdump: C{True} to log protocol traffix (in hex) to the log;
-            C{False} otherwise.
-        @type hexdump: bool
+        :param bool hexdump:
+            ``True`` to log protocol traffix (in hex) to the log; ``False``
+            otherwise.
         """
         self.packetizer.set_hexdump(hexdump)
 
     def get_hexdump(self):
         """
-        Return C{True} if the transport is currently logging hex dumps of
+        Return ``True`` if the transport is currently logging hex dumps of
         protocol traffic.
 
-        @return: C{True} if hex dumps are being logged
-        @rtype: bool
+        :return: ``True`` if hex dumps are being logged, else ``False``.
 
-        @since: 1.4
+        .. versionadded:: 1.4
         """
         return self.packetizer.get_hexdump()
 
     def use_compression(self, compress=True):
         """
         Turn on/off compression.  This will only have an affect before starting
-        the transport (ie before calling L{connect}, etc).  By default,
+        the transport (ie before calling `connect`, etc).  By default,
         compression is off since it negatively affects interactive sessions.
 
-        @param compress: C{True} to ask the remote client/server to compress
-            traffic; C{False} to refuse compression
-        @type compress: bool
+        :param bool compress:
+            ``True`` to ask the remote client/server to compress traffic;
+            ``False`` to refuse compression
 
-        @since: 1.5.2
+        .. versionadded:: 1.5.2
         """
         if compress:
-            self._preferred_compression = ( 'zlib@openssh.com', 'zlib', 'none' )
+            self._preferred_compression = ('zlib@openssh.com', 'zlib', 'none')
         else:
-            self._preferred_compression = ( 'none', )
+            self._preferred_compression = ('none',)
 
     def getpeername(self):
         """
         Return the address of the remote side of this Transport, if possible.
-        This is effectively a wrapper around C{'getpeername'} on the underlying
-        socket.  If the socket-like object has no C{'getpeername'} method,
-        then C{("unknown", 0)} is returned.
+        This is effectively a wrapper around ``'getpeername'`` on the underlying
+        socket.  If the socket-like object has no ``'getpeername'`` method,
+        then ``("unknown", 0)`` is returned.
 
-        @return: the address if the remote host, if known
-        @rtype: tuple(str, int)
+        :return:
+            the address of the remote host, if known, as a ``(str, int)``
+            tuple.
         """
         gp = getattr(self.sock, 'getpeername', None)
         if gp is None:
-            return ('unknown', 0)
+            return 'unknown', 0
         return gp()
 
     def stop_thread(self):
@@ -1394,10 +1259,8 @@ class Transport (threading.Thread):
         while self.isAlive():
             self.join(10)
 
-
     ###  internals...
 
-
     def _log(self, level, msg, *args):
         if issubclass(type(msg), list):
             for m in msg:
@@ -1406,11 +1269,11 @@ class Transport (threading.Thread):
             self.logger.log(level, msg, *args)
 
     def _get_modulus_pack(self):
-        "used by KexGex to find primes for group exchange"
+        """used by KexGex to find primes for group exchange"""
         return self._modulus_pack
 
     def _next_channel(self):
-        "you are holding the lock"
+        """you are holding the lock"""
         chanid = self._channel_counter
         while self._channels.get(chanid) is not None:
             self._channel_counter = (self._channel_counter + 1) & 0xffffff
@@ -1419,7 +1282,7 @@ class Transport (threading.Thread):
         return chanid
 
     def _unlink_channel(self, chanid):
-        "used by a Channel to remove itself from the active channel list"
+        """used by a Channel to remove itself from the active channel list"""
         self._channels.delete(chanid)
 
     def _send_message(self, data):
@@ -1448,14 +1311,14 @@ class Transport (threading.Thread):
             self.clear_to_send_lock.release()
 
     def _set_K_H(self, k, h):
-        "used by a kex object to set the K (root key) and H (exchange hash)"
+        """used by a kex object to set the K (root key) and H (exchange hash)"""
         self.K = k
         self.H = h
-        if self.session_id == None:
+        if self.session_id is None:
             self.session_id = h
 
     def _expect_packet(self, *ptypes):
-        "used by a kex object to register the next packet type it expects to see"
+        """used by a kex object to register the next packet type it expects to see"""
         self._expected_packet = tuple(ptypes)
 
     def _verify_key(self, host_key, sig):
@@ -1467,19 +1330,19 @@ class Transport (threading.Thread):
         self.host_key = key
 
     def _compute_key(self, id, nbytes):
-        "id is 'A' - 'F' for the various keys used by ssh"
+        """id is 'A' - 'F' for the various keys used by ssh"""
         m = Message()
         m.add_mpint(self.K)
         m.add_bytes(self.H)
-        m.add_byte(id)
+        m.add_byte(b(id))
         m.add_bytes(self.session_id)
-        out = sofar = SHA.new(str(m)).digest()
+        out = sofar = sha1(m.asbytes()).digest()
         while len(out) < nbytes:
             m = Message()
             m.add_mpint(self.K)
             m.add_bytes(self.H)
             m.add_bytes(sofar)
-            digest = SHA.new(str(m)).digest()
+            digest = sha1(m.asbytes()).digest()
             out += digest
             sofar += digest
         return out[:nbytes]
@@ -1513,7 +1376,7 @@ class Transport (threading.Thread):
         # only called if a channel has turned on x11 forwarding
         if handler is None:
             # by default, use the same mechanism as accept()
-            def default_handler(channel, (src_addr, src_port)):
+            def default_handler(channel, src_addr_port):
                 self._queue_incoming_channel(channel)
             self._x11_handler = default_handler
         else:
@@ -1537,19 +1400,15 @@ class Transport (threading.Thread):
         # interpreter shutdown.
         self.sys = sys
 
-        # Required to prevent RNG errors when running inside many subprocess
-        # containers.
-        Random.atfork()
-
         # active=True occurs before the thread is launched, to avoid a race
         _active_threads.append(self)
         if self.server_mode:
-            self._log(DEBUG, 'starting thread (server mode): %s' % hex(long(id(self)) & 0xffffffffL))
+            self._log(DEBUG, 'starting thread (server mode): %s' % hex(long(id(self)) & xffffffff))
         else:
-            self._log(DEBUG, 'starting thread (client mode): %s' % hex(long(id(self)) & 0xffffffffL))
+            self._log(DEBUG, 'starting thread (client mode): %s' % hex(long(id(self)) & xffffffff))
         try:
             try:
-                self.packetizer.write_all(self.local_version + '\r\n')
+                self.packetizer.write_all(b(self.local_version + '\r\n'))
                 self._check_banner()
                 self._send_kex_init()
                 self._expect_packet(MSG_KEXINIT)
@@ -1597,38 +1456,38 @@ class Transport (threading.Thread):
                     else:
                         self._log(WARNING, 'Oops, unhandled type %d' % ptype)
                         msg = Message()
-                        msg.add_byte(chr(MSG_UNIMPLEMENTED))
+                        msg.add_byte(cMSG_UNIMPLEMENTED)
                         msg.add_int(m.seqno)
                         self._send_message(msg)
-            except SSHException, e:
+            except SSHException as e:
                 self._log(ERROR, 'Exception: ' + str(e))
                 self._log(ERROR, util.tb_strings())
                 self.saved_exception = e
-            except EOFError, e:
+            except EOFError as e:
                 self._log(DEBUG, 'EOF in transport thread')
                 #self._log(DEBUG, util.tb_strings())
                 self.saved_exception = e
-            except socket.error, e:
+            except socket.error as e:
                 if type(e.args) is tuple:
                     if e.args:
                         emsg = '%s (%d)' % (e.args[1], e.args[0])
-                    else: # empty tuple, e.g. socket.timeout
+                    else:  # empty tuple, e.g. socket.timeout
                         emsg = str(e) or repr(e)
                 else:
                     emsg = e.args
                 self._log(ERROR, 'Socket exception: ' + emsg)
                 self.saved_exception = e
-            except Exception, e:
+            except Exception as e:
                 self._log(ERROR, 'Unknown exception: ' + str(e))
                 self._log(ERROR, util.tb_strings())
                 self.saved_exception = e
             _active_threads.remove(self)
-            for chan in self._channels.values():
+            for chan in list(self._channels.values()):
                 chan._unlink()
             if self.active:
                 self.active = False
                 self.packetizer.close()
-                if self.completion_event != None:
+                if self.completion_event is not None:
                     self.completion_event.set()
                 if self.auth_handler is not None:
                     self.auth_handler.abort()
@@ -1648,10 +1507,8 @@ class Transport (threading.Thread):
             if self.sys.modules is not None:
                 raise
 
-
     ###  protocol stages
 
-
     def _negotiate_keys(self, m):
         # throws SSHException on anything unusual
         self.clear_to_send_lock.acquire()
@@ -1659,7 +1516,7 @@ class Transport (threading.Thread):
             self.clear_to_send.clear()
         finally:
             self.clear_to_send_lock.release()
-        if self.local_kex_init == None:
+        if self.local_kex_init is None:
             # remote side wants to renegotiate
             self._send_kex_init()
         self._parse_kex_init(m)
@@ -1678,8 +1535,8 @@ class Transport (threading.Thread):
                 buf = self.packetizer.readline(timeout)
             except ProxyCommandFailure:
                 raise
-            except Exception, x:
-                raise SSHException('Error reading SSH protocol banner' + str(x))
+            except Exception as e:
+                raise SSHException('Error reading SSH protocol banner' + str(e))
             if buf[:4] == 'SSH-':
                 break
             self._log(DEBUG, 'Banner: ' + buf)
@@ -1689,7 +1546,7 @@ class Transport (threading.Thread):
         self.remote_version = buf
         # pull off any attached comment
         comment = ''
-        i = string.find(buf, ' ')
+        i = buf.find(' ')
         if i >= 0:
             comment = buf[i+1:]
             buf = buf[:i]
@@ -1720,14 +1577,14 @@ class Transport (threading.Thread):
                 pkex = list(self.get_security_options().kex)
                 pkex.remove('diffie-hellman-group-exchange-sha1')
                 self.get_security_options().kex = pkex
-            available_server_keys = filter(self.server_key_dict.keys().__contains__,
-                                           self._preferred_keys)
+            available_server_keys = list(filter(list(self.server_key_dict.keys()).__contains__,
+                                                self._preferred_keys))
         else:
             available_server_keys = self._preferred_keys
 
         m = Message()
-        m.add_byte(chr(MSG_KEXINIT))
-        m.add_bytes(rng.read(16))
+        m.add_byte(cMSG_KEXINIT)
+        m.add_bytes(os.urandom(16))
         m.add_list(self._preferred_kex)
         m.add_list(available_server_keys)
         m.add_list(self._preferred_ciphers)
@@ -1736,12 +1593,12 @@ class Transport (threading.Thread):
         m.add_list(self._preferred_macs)
         m.add_list(self._preferred_compression)
         m.add_list(self._preferred_compression)
-        m.add_string('')
-        m.add_string('')
+        m.add_string(bytes())
+        m.add_string(bytes())
         m.add_boolean(False)
         m.add_int(0)
         # save a copy for later (needed to compute a hash)
-        self.local_kex_init = str(m)
+        self.local_kex_init = m.asbytes()
         self._send_message(m)
 
     def _parse_kex_init(self, m):
@@ -1759,33 +1616,33 @@ class Transport (threading.Thread):
         kex_follows = m.get_boolean()
         unused = m.get_int()
 
-        self._log(DEBUG, 'kex algos:' + str(kex_algo_list) + ' server key:' + str(server_key_algo_list) + \
-                  ' client encrypt:' + str(client_encrypt_algo_list) + \
-                  ' server encrypt:' + str(server_encrypt_algo_list) + \
-                  ' client mac:' + str(client_mac_algo_list) + \
-                  ' server mac:' + str(server_mac_algo_list) + \
-                  ' client compress:' + str(client_compress_algo_list) + \
-                  ' server compress:' + str(server_compress_algo_list) + \
-                  ' client lang:' + str(client_lang_list) + \
-                  ' server lang:' + str(server_lang_list) + \
+        self._log(DEBUG, 'kex algos:' + str(kex_algo_list) + ' server key:' + str(server_key_algo_list) +
+                  ' client encrypt:' + str(client_encrypt_algo_list) +
+                  ' server encrypt:' + str(server_encrypt_algo_list) +
+                  ' client mac:' + str(client_mac_algo_list) +
+                  ' server mac:' + str(server_mac_algo_list) +
+                  ' client compress:' + str(client_compress_algo_list) +
+                  ' server compress:' + str(server_compress_algo_list) +
+                  ' client lang:' + str(client_lang_list) +
+                  ' server lang:' + str(server_lang_list) +
                   ' kex follows?' + str(kex_follows))
 
         # as a server, we pick the first item in the client's list that we support.
         # as a client, we pick the first item in our list that the server supports.
         if self.server_mode:
-            agreed_kex = filter(self._preferred_kex.__contains__, kex_algo_list)
+            agreed_kex = list(filter(self._preferred_kex.__contains__, kex_algo_list))
         else:
-            agreed_kex = filter(kex_algo_list.__contains__, self._preferred_kex)
+            agreed_kex = list(filter(kex_algo_list.__contains__, self._preferred_kex))
         if len(agreed_kex) == 0:
             raise SSHException('Incompatible ssh peer (no acceptable kex algorithm)')
         self.kex_engine = self._kex_info[agreed_kex[0]](self)
 
         if self.server_mode:
-            available_server_keys = filter(self.server_key_dict.keys().__contains__,
-                                           self._preferred_keys)
-            agreed_keys = filter(available_server_keys.__contains__, server_key_algo_list)
+            available_server_keys = list(filter(list(self.server_key_dict.keys()).__contains__,
+                                                self._preferred_keys))
+            agreed_keys = list(filter(available_server_keys.__contains__, server_key_algo_list))
         else:
-            agreed_keys = filter(server_key_algo_list.__contains__, self._preferred_keys)
+            agreed_keys = list(filter(server_key_algo_list.__contains__, self._preferred_keys))
         if len(agreed_keys) == 0:
             raise SSHException('Incompatible ssh peer (no acceptable host key)')
         self.host_key_type = agreed_keys[0]
@@ -1793,15 +1650,15 @@ class Transport (threading.Thread):
             raise SSHException('Incompatible ssh peer (can\'t match requested host key type)')
 
         if self.server_mode:
-            agreed_local_ciphers = filter(self._preferred_ciphers.__contains__,
-                                           server_encrypt_algo_list)
-            agreed_remote_ciphers = filter(self._preferred_ciphers.__contains__,
-                                          client_encrypt_algo_list)
+            agreed_local_ciphers = list(filter(self._preferred_ciphers.__contains__,
+                                           server_encrypt_algo_list))
+            agreed_remote_ciphers = list(filter(self._preferred_ciphers.__contains__,
+                                          client_encrypt_algo_list))
         else:
-            agreed_local_ciphers = filter(client_encrypt_algo_list.__contains__,
-                                          self._preferred_ciphers)
-            agreed_remote_ciphers = filter(server_encrypt_algo_list.__contains__,
-                                           self._preferred_ciphers)
+            agreed_local_ciphers = list(filter(client_encrypt_algo_list.__contains__,
+                                          self._preferred_ciphers))
+            agreed_remote_ciphers = list(filter(server_encrypt_algo_list.__contains__,
+                                           self._preferred_ciphers))
         if (len(agreed_local_ciphers) == 0) or (len(agreed_remote_ciphers) == 0):
             raise SSHException('Incompatible ssh server (no acceptable ciphers)')
         self.local_cipher = agreed_local_ciphers[0]
@@ -1809,22 +1666,22 @@ class Transport (threading.Thread):
         self._log(DEBUG, 'Ciphers agreed: local=%s, remote=%s' % (self.local_cipher, self.remote_cipher))
 
         if self.server_mode:
-            agreed_remote_macs = filter(self._preferred_macs.__contains__, client_mac_algo_list)
-            agreed_local_macs = filter(self._preferred_macs.__contains__, server_mac_algo_list)
+            agreed_remote_macs = list(filter(self._preferred_macs.__contains__, client_mac_algo_list))
+            agreed_local_macs = list(filter(self._preferred_macs.__contains__, server_mac_algo_list))
         else:
-            agreed_local_macs = filter(client_mac_algo_list.__contains__, self._preferred_macs)
-            agreed_remote_macs = filter(server_mac_algo_list.__contains__, self._preferred_macs)
+            agreed_local_macs = list(filter(client_mac_algo_list.__contains__, self._preferred_macs))
+            agreed_remote_macs = list(filter(server_mac_algo_list.__contains__, self._preferred_macs))
         if (len(agreed_local_macs) == 0) or (len(agreed_remote_macs) == 0):
             raise SSHException('Incompatible ssh server (no acceptable macs)')
         self.local_mac = agreed_local_macs[0]
         self.remote_mac = agreed_remote_macs[0]
 
         if self.server_mode:
-            agreed_remote_compression = filter(self._preferred_compression.__contains__, client_compress_algo_list)
-            agreed_local_compression = filter(self._preferred_compression.__contains__, server_compress_algo_list)
+            agreed_remote_compression = list(filter(self._preferred_compression.__contains__, client_compress_algo_list))
+            agreed_local_compression = list(filter(self._preferred_compression.__contains__, server_compress_algo_list))
         else:
-            agreed_local_compression = filter(client_compress_algo_list.__contains__, self._preferred_compression)
-            agreed_remote_compression = filter(server_compress_algo_list.__contains__, self._preferred_compression)
+            agreed_local_compression = list(filter(client_compress_algo_list.__contains__, self._preferred_compression))
+            agreed_remote_compression = list(filter(server_compress_algo_list.__contains__, self._preferred_compression))
         if (len(agreed_local_compression) == 0) or (len(agreed_remote_compression) == 0):
             raise SSHException('Incompatible ssh server (no acceptable compression) %r %r %r' % (agreed_local_compression, agreed_remote_compression, self._preferred_compression))
         self.local_compression = agreed_local_compression[0]
@@ -1839,10 +1696,10 @@ class Transport (threading.Thread):
         # actually some extra bytes (one NUL byte in openssh's case) added to
         # the end of the packet but not parsed.  turns out we need to throw
         # away those bytes because they aren't part of the hash.
-        self.remote_kex_init = chr(MSG_KEXINIT) + m.get_so_far()
+        self.remote_kex_init = cMSG_KEXINIT + m.get_so_far()
 
     def _activate_inbound(self):
-        "switch on newly negotiated encryption parameters for inbound traffic"
+        """switch on newly negotiated encryption parameters for inbound traffic"""
         block_size = self._cipher_info[self.remote_cipher]['block-size']
         if self.server_mode:
             IV_in = self._compute_key('A', block_size)
@@ -1856,9 +1713,9 @@ class Transport (threading.Thread):
         # initial mac keys are done in the hash's natural size (not the potentially truncated
         # transmission size)
         if self.server_mode:
-            mac_key = self._compute_key('E', mac_engine.digest_size)
+            mac_key = self._compute_key('E', mac_engine().digest_size)
         else:
-            mac_key = self._compute_key('F', mac_engine.digest_size)
+            mac_key = self._compute_key('F', mac_engine().digest_size)
         self.packetizer.set_inbound_cipher(engine, block_size, mac_engine, mac_size, mac_key)
         compress_in = self._compression_info[self.remote_compression][1]
         if (compress_in is not None) and ((self.remote_compression != 'zlib@openssh.com') or self.authenticated):
@@ -1866,9 +1723,9 @@ class Transport (threading.Thread):
             self.packetizer.set_inbound_compressor(compress_in())
 
     def _activate_outbound(self):
-        "switch on newly negotiated encryption parameters for outbound traffic"
+        """switch on newly negotiated encryption parameters for outbound traffic"""
         m = Message()
-        m.add_byte(chr(MSG_NEWKEYS))
+        m.add_byte(cMSG_NEWKEYS)
         self._send_message(m)
         block_size = self._cipher_info[self.local_cipher]['block-size']
         if self.server_mode:
@@ -1883,9 +1740,9 @@ class Transport (threading.Thread):
         # initial mac keys are done in the hash's natural size (not the potentially truncated
         # transmission size)
         if self.server_mode:
-            mac_key = self._compute_key('F', mac_engine.digest_size)
+            mac_key = self._compute_key('F', mac_engine().digest_size)
         else:
-            mac_key = self._compute_key('E', mac_engine.digest_size)
+            mac_key = self._compute_key('E', mac_engine().digest_size)
         sdctr = self.local_cipher.endswith('-ctr')
         self.packetizer.set_outbound_cipher(engine, block_size, mac_engine, mac_size, mac_key, sdctr)
         compress_out = self._compression_info[self.local_compression][0]
@@ -1923,7 +1780,7 @@ class Transport (threading.Thread):
             # this was the first key exchange
             self.initial_kex_done = True
         # send an event?
-        if self.completion_event != None:
+        if self.completion_event is not None:
             self.completion_event.set()
         # it's now okay to send data again (if this was a re-key)
         if not self.packetizer.need_rekey():
@@ -1937,24 +1794,24 @@ class Transport (threading.Thread):
 
     def _parse_disconnect(self, m):
         code = m.get_int()
-        desc = m.get_string()
+        desc = m.get_text()
         self._log(INFO, 'Disconnect (code %d): %s' % (code, desc))
 
     def _parse_global_request(self, m):
-        kind = m.get_string()
+        kind = m.get_text()
         self._log(DEBUG, 'Received global request "%s"' % kind)
         want_reply = m.get_boolean()
         if not self.server_mode:
             self._log(DEBUG, 'Rejecting "%s" global request from server.' % kind)
             ok = False
         elif kind == 'tcpip-forward':
-            address = m.get_string()
+            address = m.get_text()
             port = m.get_int()
             ok = self.server_object.check_port_forward_request(address, port)
-            if ok != False:
+            if ok:
                 ok = (ok,)
         elif kind == 'cancel-tcpip-forward':
-            address = m.get_string()
+            address = m.get_text()
             port = m.get_int()
             self.server_object.cancel_port_forward_request(address, port)
             ok = True
@@ -1967,10 +1824,10 @@ class Transport (threading.Thread):
         if want_reply:
             msg = Message()
             if ok:
-                msg.add_byte(chr(MSG_REQUEST_SUCCESS))
+                msg.add_byte(cMSG_REQUEST_SUCCESS)
                 msg.add(*extra)
             else:
-                msg.add_byte(chr(MSG_REQUEST_FAILURE))
+                msg.add_byte(cMSG_REQUEST_FAILURE)
             self._send_message(msg)
 
     def _parse_request_success(self, m):
@@ -2008,8 +1865,8 @@ class Transport (threading.Thread):
     def _parse_channel_open_failure(self, m):
         chanid = m.get_int()
         reason = m.get_int()
-        reason_str = m.get_string()
-        lang = m.get_string()
+        reason_str = m.get_text()
+        lang = m.get_text()
         reason_text = CONNECTION_FAILED_CODE.get(reason, '(unknown code)')
         self._log(INFO, 'Secsh channel %d open FAILED: %s: %s' % (chanid, reason_str, reason_text))
         self.lock.acquire()
@@ -2025,7 +1882,7 @@ class Transport (threading.Thread):
         return
 
     def _parse_channel_open(self, m):
-        kind = m.get_string()
+        kind = m.get_text()
         chanid = m.get_int()
         initial_window_size = m.get_int()
         max_packet_size = m.get_int()
@@ -2038,7 +1895,7 @@ class Transport (threading.Thread):
             finally:
                 self.lock.release()
         elif (kind == 'x11') and (self._x11_handler is not None):
-            origin_addr = m.get_string()
+            origin_addr = m.get_text()
             origin_port = m.get_int()
             self._log(DEBUG, 'Incoming x11 connection from %s:%d' % (origin_addr, origin_port))
             self.lock.acquire()
@@ -2047,9 +1904,9 @@ class Transport (threading.Thread):
             finally:
                 self.lock.release()
         elif (kind == 'forwarded-tcpip') and (self._tcp_handler is not None):
-            server_addr = m.get_string()
+            server_addr = m.get_text()
             server_port = m.get_int()
-            origin_addr = m.get_string()
+            origin_addr = m.get_text()
             origin_port = m.get_int()
             self._log(DEBUG, 'Incoming tcp forwarded connection from %s:%d' % (origin_addr, origin_port))
             self.lock.acquire()
@@ -2069,13 +1926,12 @@ class Transport (threading.Thread):
                 self.lock.release()
             if kind == 'direct-tcpip':
                 # handle direct-tcpip requests comming from the client
-                dest_addr = m.get_string()
+                dest_addr = m.get_text()
                 dest_port = m.get_int()
-                origin_addr = m.get_string()
+                origin_addr = m.get_text()
                 origin_port = m.get_int()
                 reason = self.server_object.check_channel_direct_tcpip_request(
-                                my_chanid, (origin_addr, origin_port),
-                                           (dest_addr, dest_port))
+                    my_chanid, (origin_addr, origin_port), (dest_addr, dest_port))
             else:
                 reason = self.server_object.check_channel_request(kind, my_chanid)
             if reason != OPEN_SUCCEEDED:
@@ -2083,7 +1939,7 @@ class Transport (threading.Thread):
                 reject = True
         if reject:
             msg = Message()
-            msg.add_byte(chr(MSG_CHANNEL_OPEN_FAILURE))
+            msg.add_byte(cMSG_CHANNEL_OPEN_FAILURE)
             msg.add_int(chanid)
             msg.add_int(reason)
             msg.add_string('')
@@ -2102,7 +1958,7 @@ class Transport (threading.Thread):
         finally:
             self.lock.release()
         m = Message()
-        m.add_byte(chr(MSG_CHANNEL_OPEN_SUCCESS))
+        m.add_byte(cMSG_CHANNEL_OPEN_SUCCESS)
         m.add_int(chanid)
         m.add_int(my_chanid)
         m.add_int(self.window_size)
@@ -2129,7 +1985,7 @@ class Transport (threading.Thread):
         try:
             self.lock.acquire()
             if name not in self.subsystem_table:
-                return (None, [], {})
+                return None, [], {}
             return self.subsystem_table[name]
         finally:
             self.lock.release()
@@ -2143,7 +1999,7 @@ class Transport (threading.Thread):
         MSG_CHANNEL_OPEN_FAILURE: _parse_channel_open_failure,
         MSG_CHANNEL_OPEN: _parse_channel_open,
         MSG_KEXINIT: _negotiate_keys,
-        }
+    }
 
     _channel_handler_table = {
         MSG_CHANNEL_SUCCESS: Channel._request_success,
@@ -2154,4 +2010,125 @@ class Transport (threading.Thread):
         MSG_CHANNEL_REQUEST: Channel._handle_request,
         MSG_CHANNEL_EOF: Channel._handle_eof,
         MSG_CHANNEL_CLOSE: Channel._handle_close,
-        }
+    }
+
+
+class SecurityOptions (object):
+    """
+    Simple object containing the security preferences of an ssh transport.
+    These are tuples of acceptable ciphers, digests, key types, and key
+    exchange algorithms, listed in order of preference.
+
+    Changing the contents and/or order of these fields affects the underlying
+    `.Transport` (but only if you change them before starting the session).
+    If you try to add an algorithm that paramiko doesn't recognize,
+    ``ValueError`` will be raised.  If you try to assign something besides a
+    tuple to one of the fields, ``TypeError`` will be raised.
+    """
+    #__slots__ = [ 'ciphers', 'digests', 'key_types', 'kex', 'compression', '_transport' ]
+    __slots__ = '_transport'
+
+    def __init__(self, transport):
+        self._transport = transport
+
+    def __repr__(self):
+        """
+        Returns a string representation of this object, for debugging.
+        """
+        return '<paramiko.SecurityOptions for %s>' % repr(self._transport)
+
+    def _get_ciphers(self):
+        return self._transport._preferred_ciphers
+
+    def _get_digests(self):
+        return self._transport._preferred_macs
+
+    def _get_key_types(self):
+        return self._transport._preferred_keys
+
+    def _get_kex(self):
+        return self._transport._preferred_kex
+
+    def _get_compression(self):
+        return self._transport._preferred_compression
+
+    def _set(self, name, orig, x):
+        if type(x) is list:
+            x = tuple(x)
+        if type(x) is not tuple:
+            raise TypeError('expected tuple or list')
+        possible = list(getattr(self._transport, orig).keys())
+        forbidden = [n for n in x if n not in possible]
+        if len(forbidden) > 0:
+            raise ValueError('unknown cipher')
+        setattr(self._transport, name, x)
+
+    def _set_ciphers(self, x):
+        self._set('_preferred_ciphers', '_cipher_info', x)
+
+    def _set_digests(self, x):
+        self._set('_preferred_macs', '_mac_info', x)
+
+    def _set_key_types(self, x):
+        self._set('_preferred_keys', '_key_info', x)
+
+    def _set_kex(self, x):
+        self._set('_preferred_kex', '_kex_info', x)
+
+    def _set_compression(self, x):
+        self._set('_preferred_compression', '_compression_info', x)
+
+    ciphers = property(_get_ciphers, _set_ciphers, None,
+                       "Symmetric encryption ciphers")
+    digests = property(_get_digests, _set_digests, None,
+                       "Digest (one-way hash) algorithms")
+    key_types = property(_get_key_types, _set_key_types, None,
+                         "Public-key algorithms")
+    kex = property(_get_kex, _set_kex, None, "Key exchange algorithms")
+    compression = property(_get_compression, _set_compression, None,
+                           "Compression algorithms")
+
+
+class ChannelMap (object):
+    def __init__(self):
+        # (id -> Channel)
+        self._map = weakref.WeakValueDictionary()
+        self._lock = threading.Lock()
+
+    def put(self, chanid, chan):
+        self._lock.acquire()
+        try:
+            self._map[chanid] = chan
+        finally:
+            self._lock.release()
+
+    def get(self, chanid):
+        self._lock.acquire()
+        try:
+            return self._map.get(chanid, None)
+        finally:
+            self._lock.release()
+
+    def delete(self, chanid):
+        self._lock.acquire()
+        try:
+            try:
+                del self._map[chanid]
+            except KeyError:
+                pass
+        finally:
+            self._lock.release()
+
+    def values(self):
+        self._lock.acquire()
+        try:
+            return list(self._map.values())
+        finally:
+            self._lock.release()
+
+    def __len__(self):
+        self._lock.acquire()
+        try:
+            return len(self._map)
+        finally:
+            self._lock.release()
diff --git a/paramiko/util.py b/paramiko/util.py
index 85ee6b0..f4ee3ad 100644
--- a/paramiko/util.py
+++ b/paramiko/util.py
@@ -29,78 +29,65 @@ import sys
 import struct
 import traceback
 import threading
+import logging
 
-from paramiko.common import *
+from paramiko.common import DEBUG, zero_byte, xffffffff, max_byte
+from paramiko.py3compat import PY2, long, byte_ord, b, byte_chr
 from paramiko.config import SSHConfig
 
 
-# Change by RogerB - python < 2.3 doesn't have enumerate so we implement it
-if sys.version_info < (2,3):
-    class enumerate:
-        def __init__ (self, sequence):
-            self.sequence = sequence
-        def __iter__ (self):
-            count = 0
-            for item in self.sequence:
-                yield (count, item)
-                count += 1
-
-
 def inflate_long(s, always_positive=False):
-    "turns a normalized byte string into a long-int (adapted from Crypto.Util.number)"
-    out = 0L
+    """turns a normalized byte string into a long-int (adapted from Crypto.Util.number)"""
+    out = long(0)
     negative = 0
-    if not always_positive and (len(s) > 0) and (ord(s[0]) >= 0x80):
+    if not always_positive and (len(s) > 0) and (byte_ord(s[0]) >= 0x80):
         negative = 1
     if len(s) % 4:
-        filler = '\x00'
+        filler = zero_byte
         if negative:
-            filler = '\xff'
+            filler = max_byte
+        # never convert this to ``s +=`` because this is a string, not a number
+        # noinspection PyAugmentAssignment
         s = filler * (4 - len(s) % 4) + s
     for i in range(0, len(s), 4):
         out = (out << 32) + struct.unpack('>I', s[i:i+4])[0]
     if negative:
-        out -= (1L << (8 * len(s)))
+        out -= (long(1) << (8 * len(s)))
     return out
 
+deflate_zero = zero_byte if PY2 else 0
+deflate_ff = max_byte if PY2 else 0xff
+
+
 def deflate_long(n, add_sign_padding=True):
-    "turns a long-int into a normalized byte string (adapted from Crypto.Util.number)"
+    """turns a long-int into a normalized byte string (adapted from Crypto.Util.number)"""
     # after much testing, this algorithm was deemed to be the fastest
-    s = ''
+    s = bytes()
     n = long(n)
     while (n != 0) and (n != -1):
-        s = struct.pack('>I', n & 0xffffffffL) + s
-        n = n >> 32
+        s = struct.pack('>I', n & xffffffff) + s
+        n >>= 32
     # strip off leading zeros, FFs
     for i in enumerate(s):
-        if (n == 0) and (i[1] != '\000'):
+        if (n == 0) and (i[1] != deflate_zero):
             break
-        if (n == -1) and (i[1] != '\xff'):
+        if (n == -1) and (i[1] != deflate_ff):
             break
     else:
         # degenerate case, n was either 0 or -1
         i = (0,)
         if n == 0:
-            s = '\000'
+            s = zero_byte
         else:
-            s = '\xff'
+            s = max_byte
     s = s[i[0]:]
     if add_sign_padding:
-        if (n == 0) and (ord(s[0]) >= 0x80):
-            s = '\x00' + s
-        if (n == -1) and (ord(s[0]) < 0x80):
-            s = '\xff' + s
+        if (n == 0) and (byte_ord(s[0]) >= 0x80):
+            s = zero_byte + s
+        if (n == -1) and (byte_ord(s[0]) < 0x80):
+            s = max_byte + s
     return s
 
-def format_binary_weird(data):
-    out = ''
-    for i in enumerate(data):
-        out += '%02X' % ord(i[1])
-        if i[0] % 2:
-            out += ' '
-        if i[0] % 16 == 15:
-            out += '\n'
-    return out
 
 def format_binary(data, prefix=''):
     x = 0
@@ -112,69 +99,73 @@ def format_binary(data, prefix=''):
         out.append(format_binary_line(data[x:]))
     return [prefix + x for x in out]
 
+
 def format_binary_line(data):
-    left = ' '.join(['%02X' % ord(c) for c in data])
-    right = ''.join([('.%c..' % c)[(ord(c)+63)//95] for c in data])
+    left = ' '.join(['%02X' % byte_ord(c) for c in data])
+    right = ''.join([('.%c..' % c)[(byte_ord(c)+63)//95] for c in data])
     return '%-50s %s' % (left, right)
 
+
 def hexify(s):
     return hexlify(s).upper()
 
+
 def unhexify(s):
     return unhexlify(s)
 
+
 def safe_string(s):
     out = ''
     for c in s:
-        if (ord(c) >= 32) and (ord(c) <= 127):
+        if (byte_ord(c) >= 32) and (byte_ord(c) <= 127):
             out += c
         else:
-            out += '%%%02X' % ord(c)
+            out += '%%%02X' % byte_ord(c)
     return out
 
-# ''.join([['%%%02X' % ord(c), c][(ord(c) >= 32) and (ord(c) <= 127)] for c in s])
 
 def bit_length(n):
-    norm = deflate_long(n, 0)
-    hbyte = ord(norm[0])
-    if hbyte == 0:
-        return 1
-    bitlen = len(norm) * 8
-    while not (hbyte & 0x80):
-        hbyte <<= 1
-        bitlen -= 1
-    return bitlen
+    try:
+        return n.bitlength()
+    except AttributeError:
+        norm = deflate_long(n, False)
+        hbyte = byte_ord(norm[0])
+        if hbyte == 0:
+            return 1
+        bitlen = len(norm) * 8
+        while not (hbyte & 0x80):
+            hbyte <<= 1
+            bitlen -= 1
+        return bitlen
+
 
 def tb_strings():
     return ''.join(traceback.format_exception(*sys.exc_info())).split('\n')
 
-def generate_key_bytes(hashclass, salt, key, nbytes):
+
+def generate_key_bytes(hash_alg, salt, key, nbytes):
     """
     Given a password, passphrase, or other human-source key, scramble it
     through a secure hash into some keyworthy bytes.  This specific algorithm
     is used for encrypting/decrypting private key files.
 
-    @param hashclass: class from L{Crypto.Hash} that can be used as a secure
-        hashing function (like C{MD5} or C{SHA}).
-    @type hashclass: L{Crypto.Hash}
-    @param salt: data to salt the hash with.
-    @type salt: string
-    @param key: human-entered password or passphrase.
-    @type key: string
-    @param nbytes: number of bytes to generate.
-    @type nbytes: int
-    @return: key data
-    @rtype: string
+    :param function hash_alg: A function which creates a new hash object, such
+        as ``hashlib.sha256``.
+    :param salt: data to salt the hash with.
+    :type salt: byte string
+    :param str key: human-entered password or passphrase.
+    :param int nbytes: number of bytes to generate.
+    :return: Key data `str`
     """
-    keydata = ''
-    digest = ''
+    keydata = bytes()
+    digest = bytes()
     if len(salt) > 8:
         salt = salt[:8]
     while nbytes > 0:
-        hash_obj = hashclass.new()
+        hash_obj = hash_alg()
         if len(digest) > 0:
             hash_obj.update(digest)
-        hash_obj.update(key)
+        hash_obj.update(b(key))
         hash_obj.update(salt)
         digest = hash_obj.digest()
         size = min(nbytes, len(digest))
@@ -182,42 +173,45 @@ def generate_key_bytes(hashclass, salt, key, nbytes):
         nbytes -= size
     return keydata
 
+
 def load_host_keys(filename):
     """
     Read a file of known SSH host keys, in the format used by openssh, and
-    return a compound dict of C{hostname -> keytype ->} L{PKey <paramiko.pkey.PKey>}.
-    The hostname may be an IP address or DNS name.  The keytype will be either
-    C{"ssh-rsa"} or C{"ssh-dss"}.
+    return a compound dict of ``hostname -> keytype ->`` `PKey
+    <paramiko.pkey.PKey>`. The hostname may be an IP address or DNS name.  The
+    keytype will be either ``"ssh-rsa"`` or ``"ssh-dss"``.
 
     This type of file unfortunately doesn't exist on Windows, but on posix,
-    it will usually be stored in C{os.path.expanduser("~/.ssh/known_hosts")}.
+    it will usually be stored in ``os.path.expanduser("~/.ssh/known_hosts")``.
 
-    Since 1.5.3, this is just a wrapper around L{HostKeys}.
+    Since 1.5.3, this is just a wrapper around `.HostKeys`.
 
-    @param filename: name of the file to read host keys from
-    @type filename: str
-    @return: dict of host keys, indexed by hostname and then keytype
-    @rtype: dict(hostname, dict(keytype, L{PKey <paramiko.pkey.PKey>}))
+    :param str filename: name of the file to read host keys from
+    :return:
+        nested dict of `.PKey` objects, indexed by hostname and then keytype
     """
     from paramiko.hostkeys import HostKeys
     return HostKeys(filename)
 
+
 def parse_ssh_config(file_obj):
     """
-    Provided only as a backward-compatible wrapper around L{SSHConfig}.
+    Provided only as a backward-compatible wrapper around `.SSHConfig`.
     """
     config = SSHConfig()
     config.parse(file_obj)
     return config
 
+
 def lookup_ssh_host_config(hostname, config):
     """
-    Provided only as a backward-compatible wrapper around L{SSHConfig}.
+    Provided only as a backward-compatible wrapper around `.SSHConfig`.
     """
     return config.lookup(hostname)
 
+
 def mod_inverse(x, m):
-    # it's crazy how small python can make this function.
+    # it's crazy how small Python can make this function.
     u1, u2, u3 = 1, 0, m
     v1, v2, v3 = 0, 1, x
 
@@ -233,6 +227,8 @@ def mod_inverse(x, m):
 _g_thread_ids = {}
 _g_thread_counter = 0
 _g_thread_lock = threading.Lock()
+
+
 def get_thread_id():
     global _g_thread_ids, _g_thread_counter, _g_thread_lock
     tid = id(threading.currentThread())
@@ -247,8 +243,9 @@ def get_thread_id():
             _g_thread_lock.release()
         return ret
 
+
 def log_to_file(filename, level=DEBUG):
-    "send paramiko logs to a logfile, if they're not already going somewhere"
+    """send paramiko logs to a logfile, if they're not already going somewhere"""
     l = logging.getLogger("paramiko")
     if len(l.handlers) > 0:
         return
@@ -259,6 +256,7 @@ def log_to_file(filename, level=DEBUG):
                                       '%Y%m%d-%H:%M:%S'))
     l.addHandler(lh)
 
+
 # make only one filter object, so it doesn't get applied more than once
 class PFilter (object):
     def filter(self, record):
@@ -266,46 +264,59 @@ class PFilter (object):
         return True
 _pfilter = PFilter()
 
+
 def get_logger(name):
     l = logging.getLogger(name)
     l.addFilter(_pfilter)
     return l
 
+
 def retry_on_signal(function):
     """Retries function until it doesn't raise an EINTR error"""
     while True:
         try:
             return function()
-        except EnvironmentError, e:
+        except EnvironmentError as e:
             if e.errno != errno.EINTR:
                 raise
 
+
 class Counter (object):
     """Stateful counter for CTR mode crypto"""
-    def __init__(self, nbits, initial_value=1L, overflow=0L):
+    def __init__(self, nbits, initial_value=long(1), overflow=long(0)):
         self.blocksize = nbits / 8
         self.overflow = overflow
         # start with value - 1 so we don't have to store intermediate values when counting
         # could the iv be 0?
         if initial_value == 0:
-            self.value = array.array('c', '\xFF' * self.blocksize)
+            self.value = array.array('c', max_byte * self.blocksize)
         else:
             x = deflate_long(initial_value - 1, add_sign_padding=False)
-            self.value = array.array('c', '\x00' * (self.blocksize - len(x)) + x)
+            self.value = array.array('c', zero_byte * (self.blocksize - len(x)) + x)
 
     def __call__(self):
         """Increament the counter and return the new value"""
         i = self.blocksize - 1
         while i > -1:
-            c = self.value[i] = chr((ord(self.value[i]) + 1) % 256)
-            if c != '\x00':
+            c = self.value[i] = byte_chr((byte_ord(self.value[i]) + 1) % 256)
+            if c != zero_byte:
                 return self.value.tostring()
             i -= 1
         # counter reset
         x = deflate_long(self.overflow, add_sign_padding=False)
-        self.value = array.array('c', '\x00' * (self.blocksize - len(x)) + x)
+        self.value = array.array('c', zero_byte * (self.blocksize - len(x)) + x)
         return self.value.tostring()
 
-    def new(cls, nbits, initial_value=1L, overflow=0L):
+    def new(cls, nbits, initial_value=long(1), overflow=long(0)):
         return cls(nbits, initial_value=initial_value, overflow=overflow)
     new = classmethod(new)
+
+
+def constant_time_bytes_eq(a, b):
+    if len(a) != len(b):
+        return False
+    res = 0
+    # noinspection PyUnresolvedReferences
+    for i in (xrange if PY2 else range)(len(a)):
+        res |= byte_ord(a[i]) ^ byte_ord(b[i])
+    return res == 0
diff --git a/paramiko/win_pageant.py b/paramiko/win_pageant.py
index d588e81..20b1b0b 100644
--- a/paramiko/win_pageant.py
+++ b/paramiko/win_pageant.py
@@ -21,12 +21,11 @@
 Functions for communicating with Pageant, the basic windows ssh agent program.
 """
 
-from __future__ import with_statement
-
 import array
 import ctypes.wintypes
 import platform
 import struct
+from paramiko.util import *
 
 try:
     import _thread as thread # Python 3.x
@@ -91,7 +90,7 @@ def _query_pageant(msg):
     with pymap:
         pymap.write(msg)
         # Create an array buffer containing the mapped filename
-        char_buffer = array.array("c", map_name + '\0')
+        char_buffer = array.array("c", b(map_name) + zero_byte)
         char_buffer_address, char_buffer_size = char_buffer.buffer_info()
         # Create a string to use for the SendMessage function call
         cds = COPYDATASTRUCT(_AGENT_COPYDATA_ID, char_buffer_size,