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.. _security:
Security: Verified HTTPS with SSL/TLS
=====================================
Very important fact: **By default, urllib3 does not verify HTTPS requests.**
The historic reason for this is that we rely on ``httplib`` for some of the
HTTP protocol implementation, and ``httplib`` does not verify requests out of
the box. This is not a good reason, but here we are.
Luckily, it's not too hard to enable verified HTTPS requests and there are a
few ways to do it.
Python with SSL enabled
-----------------------
First we need to make sure your Python installation has SSL enabled. Easiest
way to check is to simply open a Python shell and type `import ssl`::
>>> import ssl
Traceback (most recent call last):
...
ImportError: No module named _ssl
If you got an ``ImportError``, then your Python is not compiled with SSL support
and you'll need to re-install it. Read
`this StackOverflow thread <https://stackoverflow.com/questions/5128845/importerror-no-module-named-ssl>`_
for details.
Otherwise, if ``ssl`` imported cleanly, then we're ready to setup our certificates:
:ref:`certifi-with-urllib3`.
Enabling SSL on Google AppEngine
++++++++++++++++++++++++++++++++
If you're using Google App Engine, you'll need to add ``ssl`` as a library
dependency to your yaml file, like this::
libraries:
- name: ssl
version: latest
If it's still not working, you may need to enable billing on your account
to `enable using sockets
<https://developers.google.com/appengine/docs/python/sockets/>`_.
.. _certifi-with-urllib3:
Using Certifi with urllib3
--------------------------
`Certifi <http://certifi.io/>`_ is a package which ships with Mozilla's root
certificates for easy programmatic access.
1. Install the Python ``certifi`` package::
$ pip install certifi
2. Setup your pool to require a certificate and provide the certifi bundle::
import urllib3
import certifi
http = urllib3.PoolManager(
cert_reqs='CERT_REQUIRED', # Force certificate check.
ca_certs=certifi.where(), # Path to the Certifi bundle.
)
# You're ready to make verified HTTPS requests.
try:
r = http.request('GET', 'https://example.com/')
except urllib3.exceptions.SSLError as e:
# Handle incorrect certificate error.
...
Make sure to update your ``certifi`` package regularly to get the latest root
certificates.
Using your system's root certificates
-------------------------------------
Your system's root certificates may be more up-to-date than maintaining your
own, but the trick is finding where they live. Different operating systems have
them in different places.
For example, on most Linux distributions they're at
``/etc/ssl/certs/ca-certificates.crt``. On Windows and OS X? `It's not so simple
<https://stackoverflow.com/questions/10095676/openssl-reasonable-default-for-trusted-ca-certificates>`_.
Once you find your root certificate file::
import urllib3
ca_certs = "/etc/ssl/certs/ca-certificates.crt" # Or wherever it lives.
http = urllib3.PoolManager(
cert_reqs='CERT_REQUIRED', # Force certificate check.
ca_certs=ca_certs, # Path to your certificate bundle.
)
# You're ready to make verified HTTPS requests.
try:
r = http.request('GET', 'https://example.com/')
except urllib3.exceptions.SSLError as e:
# Handle incorrect certificate error.
...
OpenSSL / PyOpenSSL
-------------------
By default, we use the standard library's ``ssl`` module. Unfortunately, there
are several limitations which are addressed by PyOpenSSL:
- (Python 2.x) SNI support.
- (Python 2.x-3.2) Disabling compression to mitigate `CRIME attack
<https://en.wikipedia.org/wiki/CRIME_(security_exploit)>`_.
To use the Python OpenSSL bindings instead, you'll need to install the required
packages::
$ pip install pyopenssl ndg-httpsclient pyasn1
Once the packages are installed, you can tell urllib3 to switch the ssl backend
to PyOpenSSL with :func:`~urllib3.contrib.pyopenssl.inject_into_urllib3`::
import urllib3.contrib.pyopenssl
urllib3.contrib.pyopenssl.inject_into_urllib3()
Now you can continue using urllib3 as you normally would.
For more details, check the :mod:`~urllib3.contrib.pyopenssl` module.
InsecureRequestWarning
----------------------
.. versionadded:: 1.9
Unverified HTTPS requests will trigger a warning::
urllib3/connectionpool.py:736: InsecureRequestWarning: Unverified HTTPS
request is being made. Adding certificate verification is strongly advised.
See: https://urllib3.readthedocs.org/en/latest/security.html
(This warning will only appear once by default.)
This would be a great time to enable HTTPS verification:
:ref:`certifi-with-urllib3`.
If you know what you're doing and would like to disable this and other warnings,
you can use :func:`~urllib3.disable_warnings`::
import urllib3
urllib3.disable_warnings()
Making unverified HTTPS requests is strongly discouraged. ˙ ͜ʟ˙
|