gnu: security: Add fail2ban-service-type.

* gnu/services/security.scm: New module.
* gnu/tests/security.scm: New module.
* gnu/local.mk: Add new security module and tests.
* doc/guix.text: Add fail2ban-service-type documentation.

Signed-off-by: Maxim Cournoyer <maxim.cournoyer@gmail.com>

4 files changed, 888 insertions, 0 deletions

diff --git a/doc/guix.texi b/doc/guix.texi
index 7bce8a567c..4f6973518f 100644
--- a/doc/guix.texi
+++ b/doc/guix.texi
@@ -36311,6 +36311,255 @@ Extra command line options for @code{nix-service-type}.
 @end table
 @end deftp
 
+@cindex Fail2Ban
+@subsubheading Fail2Ban service
+
+@uref{http://www.fail2ban.org/, @code{fail2ban}} scans log files
+(e.g. @code{/var/log/apache/error_log}) and bans IP addresses that show
+malicious signs -- repeated password failures, attempts to make use of
+exploits, etc.
+
+@code{fail2ban-service-type} service type is provided by the @code{(gnu
+services security)} module.
+
+This service type runs the @code{fail2ban} daemon.  It can be configured
+in various ways, which are:
+
+@table @asis
+@item Basic configuration
+The basic parameters of the Fail2Ban service can be configured via its
+@code{fail2ban} configuration, which is documented below.
+
+@item User-specified jail extensions
+The @code{fail2ban-jail-service} function can be used to add new
+Fail2Ban jails.
+
+@item Shepherd extension mechanism
+Service developers can extend the @code{fail2ban-service-type} service
+type itself via the usual service extension mechanism.
+@end table
+
+@defvr {Scheme Variable} fail2ban-service-type
+
+This is the type of the service that runs @code{fail2ban} daemon.  Below
+is an example of a basic, explicit configuration:
+
+@lisp
+(append
+ (list
+  (service fail2ban-service-type
+           (fail2ban-configuration
+            (extra-jails
+             (list
+              (fail2ban-jail-configuration
+               (name "sshd")
+               (enabled #t))))))
+  ;; There is no implicit dependency on an actual SSH
+  ;; service, so you need to provide one.
+  (service openssh-service-type))
+ %base-services)
+@end lisp
+@end defvr
+
+@deffn {Scheme Procedure} fail2ban-jail-service @var{svc-type} @var{jail}
+Extend @var{svc-type}, a @code{<service-type>} object with @var{jail}, a
+@code{fail2ban-jail-configuration} object.
+
+For example:
+
+@lisp
+(append
+ (list
+  (service
+   ;; The 'fail2ban-jail-service' procedure can extend any service type
+   ;; with a fail2ban jail.  This removes the requirement to explicitly
+   ;; extend services with fail2ban-service-type.
+   (fail2ban-jail-service
+    openssh-service-type
+    (fail2ban-jail-configuration
+     (name "sshd")
+     (enabled #t)))
+   (openssh-configuration ...))))
+@end lisp
+@end deffn
+
+Below is the reference for the different @code{jail-service-type}
+configuration records.
+
+@c The documentation is to be auto-generated via
+@c 'generate-documentation'.  See at the bottom of (gnu services
+@c security).
+
+@deftp {Data Type} fail2ban-configuration
+Available @code{fail2ban-configuration} fields are:
+
+@table @asis
+@item @code{fail2ban} (default: @code{fail2ban}) (type: package)
+The @code{fail2ban} package to use.  It is used for both binaries and as
+base default configuration that is to be extended with
+@code{<fail2ban-jail-configuration>} objects.
+
+@item @code{run-directory} (default: @code{"/var/run/fail2ban"}) (type: string)
+The state directory for the @code{fail2ban} daemon.
+
+@item @code{jails} (default: @code{()}) (type: list-of-fail2ban-jail-configurations)
+Instances of @code{<fail2ban-jail-configuration>} collected from
+extensions.
+
+@item @code{extra-jails} (default: @code{()}) (type: list-of-fail2ban-jail-configurations)
+Instances of @code{<fail2ban-jail-configuration>} explicitly provided.
+
+@item @code{extra-content} (type: maybe-string)
+Extra raw content to add to the end of the @file{jail.local} file.
+
+@end table
+
+@end deftp
+
+@deftp {Data Type} fail2ban-ignore-cache-configuration
+Available @code{fail2ban-ignore-cache-configuration} fields are:
+
+@table @asis
+@item @code{key} (type: string)
+Cache key.
+
+@item @code{max-count} (type: integer)
+Cache size.
+
+@item @code{max-time} (type: integer)
+Cache time.
+
+@end table
+
+@end deftp
+
+@deftp {Data Type} fail2ban-jail-action-configuration
+Available @code{fail2ban-jail-action-configuration} fields are:
+
+@table @asis
+@item @code{name} (type: string)
+Action name.
+
+@item @code{arguments} (default: @code{()}) (type: list-of-arguments)
+Action arguments.
+
+@end table
+
+@end deftp
+
+@deftp {Data Type} fail2ban-jail-configuration
+Available @code{fail2ban-jail-configuration} fields are:
+
+@table @asis
+@item @code{name} (type: string)
+Required name of this jail configuration.
+
+@item @code{enabled?} (default: @code{#t}) (type: boolean)
+Whether this jail is enabled.
+
+@item @code{backend} (type: maybe-symbol)
+Backend to use to detect changes in the @code{ogpath}.  The default is
+'auto.  To consult the defaults of the jail configuration, refer to the
+@file{/etc/fail2ban/jail.conf} file of the @code{fail2ban} package.
+
+@item @code{max-retry} (type: maybe-integer)
+The number of failures before a host get banned (e.g.  @code{(max-retry
+5)}).
+
+@item @code{max-matches} (type: maybe-integer)
+The number of matches stored in ticket (resolvable via tag
+@code{<matches>}) in action.
+
+@item @code{find-time} (type: maybe-string)
+The time window during which the maximum retry count must be reached for
+an IP address to be banned.  A host is banned if it has generated
+@code{max-retry} during the last @code{find-time} seconds (e.g.
+@code{(find-time "10m")}).  It can be provided in seconds or using
+Fail2Ban's "time abbreviation format", as described in @command{man 5
+jail.conf}.
+
+@item @code{ban-time} (type: maybe-string)
+The duration, in seconds or time abbreviated format, that a ban should
+last.  (e.g.  @code{(ban-time "10m")}).
+
+@item @code{ban-time-increment?} (type: maybe-boolean)
+Whether to consider past bans to compute increases to the default ban
+time of a specific IP address.
+
+@item @code{ban-time-factor} (type: maybe-string)
+The coefficient to use to compute an exponentially growing ban time.
+
+@item @code{ban-time-formula} (type: maybe-string)
+This is the formula used to calculate the next value of a ban time.
+
+@item @code{ban-time-multipliers} (type: maybe-string)
+Used to calculate next value of ban time instead of formula.
+
+@item @code{ban-time-max-time} (type: maybe-string)
+The maximum number of seconds a ban should last.
+
+@item @code{ban-time-rnd-time} (type: maybe-string)
+The maximum number of seconds a randomized ban time should last.  This
+can be useful to stop ``clever'' botnets calculating the exact time an
+IP address can be unbanned again.
+
+@item @code{ban-time-overall-jails?} (type: maybe-boolean)
+When true, it specifies the search of an IP address in the database
+should be made across all jails.  Otherwise, only the current jail of
+the ban IP address is considered.
+
+@item @code{ignore-self?} (type: maybe-boolean)
+Never ban the local machine's own IP address.
+
+@item @code{ignore-ip} (default: @code{()}) (type: list-of-strings)
+A list of IP addresses, CIDR masks or DNS hosts to ignore.
+@code{fail2ban} will not ban a host which matches an address in this
+list.
+
+@item @code{ignore-cache} (type: maybe-fail2ban-ignore-cache-configuration)
+Provide cache parameters for the ignore failure check.
+
+@item @code{filter} (type: maybe-fail2ban-jail-filter-configuration)
+The filter to use by the jail, specified via a
+@code{<fail2ban-jail-filter-configuration>} object.  By default, jails
+have names matching their filter name.
+
+@item @code{log-time-zone} (type: maybe-string)
+The default time zone for log lines that do not have one.
+
+@item @code{log-encoding} (type: maybe-symbol)
+The encoding of the log files handled by the jail.  Possible values are:
+@code{'ascii}, @code{'utf-8} and @code{'auto}.
+
+@item @code{log-path} (default: @code{()}) (type: list-of-strings)
+The file names of the log files to be monitored.
+
+@item @code{action} (default: @code{()}) (type: list-of-fail2ban-jail-actions)
+A list of @code{<fail2ban-jail-action-configuration>}.
+
+@item @code{extra-content} (type: maybe-string)
+Extra content for the jail configuration.
+
+@end table
+
+@end deftp
+
+@deftp {Data Type} fail2ban-jail-filter-configuration
+Available @code{fail2ban-jail-filter-configuration} fields are:
+
+@table @asis
+@item @code{name} (type: string)
+Filter to use.
+
+@item @code{mode} (type: maybe-string)
+Mode for filter.
+
+@end table
+
+@end deftp
+
+@c End of auto-generated fail2ban documentation.
+
 @node Setuid Programs
 @section Setuid Programs
 
diff --git a/gnu/local.mk b/gnu/local.mk
index 027cb8e3cb..fcbbdbd1fb 100644
--- a/gnu/local.mk
+++ b/gnu/local.mk
@@ -51,6 +51,7 @@
 # Copyright © 2022 Remco van 't Veer <remco@remworks.net>
 # Copyright © 2022 Artyom V. Poptsov <poptsov.artyom@gmail.com>
 # Copyright © 2022 John Kehayias <john.kehayias@protonmail.com>
+# Copyright © 2022 muradm <mail@muradm.net>
 #
 # This file is part of GNU Guix.
 #
@@ -672,6 +673,7 @@ GNU_SYSTEM_MODULES =				\
   %D%/services/nfs.scm			\
   %D%/services/pam-mount.scm			\
   %D%/services/science.scm			\
+  %D%/services/security.scm			\
   %D%/services/security-token.scm		\
   %D%/services/shepherd.scm			\
   %D%/services/sound.scm			\
@@ -756,6 +758,7 @@ GNU_SYSTEM_MODULES =				\
   %D%/tests/package-management.scm		\
   %D%/tests/reconfigure.scm			\
   %D%/tests/rsync.scm				\
+  %D%/tests/security.scm			\
   %D%/tests/security-token.scm			\
   %D%/tests/singularity.scm			\
   %D%/tests/ssh.scm				\
diff --git a/gnu/services/security.scm b/gnu/services/security.scm
new file mode 100644
index 0000000000..1e0360c07f
--- /dev/null
+++ b/gnu/services/security.scm
@@ -0,0 +1,415 @@
+;;; GNU Guix --- Functional package management for GNU
+;;; Copyright © 2022 muradm <mail@muradm.net>
+;;;
+;;; This file is part of GNU Guix.
+;;;
+;;; GNU Guix is free software; you can redistribute it and/or modify it
+;;; under the terms of the GNU General Public License as published by
+;;; the Free Software Foundation; either version 3 of the License, or (at
+;;; your option) any later version.
+;;;
+;;; GNU Guix 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 General Public License for more details.
+;;;
+;;; You should have received a copy of the GNU General Public License
+;;; along with GNU Guix.  If not, see <http://www.gnu.org/licenses/>.
+
+(define-module (gnu services security)
+  #:use-module (gnu packages admin)
+  #:use-module (gnu services)
+  #:use-module (gnu services configuration)
+  #:use-module (gnu services shepherd)
+  #:use-module (guix gexp)
+  #:use-module (guix packages)
+  #:use-module (guix records)
+  #:use-module (guix ui)
+  #:use-module (ice-9 format)
+  #:use-module (ice-9 match)
+  #:use-module (srfi srfi-1)
+  #:export (fail2ban-configuration
+            fail2ban-ignore-cache-configuration
+            fail2ban-jail-action-configuration
+            fail2ban-jail-configuration
+            fail2ban-jail-filter-configuration
+            fail2ban-jail-service
+            fail2ban-service-type))
+
+(define-configuration/no-serialization fail2ban-ignore-cache-configuration
+  (key string "Cache key.")
+  (max-count integer "Cache size.")
+  (max-time integer "Cache time."))
+
+(define serialize-fail2ban-ignore-cache-configuration
+  (match-lambda
+    (($ <fail2ban-ignore-cache-configuration> _ key max-count max-time)
+     (format #f "key=\"~a\", max-count=~d, max-time=~d"
+             key max-count max-time))))
+
+(define-maybe/no-serialization string)
+
+(define-configuration/no-serialization fail2ban-jail-filter-configuration
+  (name string "Filter to use.")
+  (mode maybe-string "Mode for filter."))
+
+(define serialize-fail2ban-jail-filter-configuration
+  (match-lambda
+    (($ <fail2ban-jail-filter-configuration> _ name mode)
+     (format #f "~a~@[[mode=~a]~]" name (maybe-value mode)))))
+
+(define (argument? a)
+  (and (pair? a)
+       (string? (car a))
+       (or (string? (cdr a))
+           (list-of-strings? (cdr a)))))
+
+(define list-of-arguments? (list-of argument?))
+
+(define-configuration/no-serialization fail2ban-jail-action-configuration
+  (name string "Action name.")
+  (arguments (list-of-arguments '()) "Action arguments."))
+
+(define list-of-fail2ban-jail-actions?
+  (list-of fail2ban-jail-action-configuration?))
+
+(define (serialize-fail2ban-jail-action-configuration-arguments args)
+  (let* ((multi-value
+          (lambda (v)
+            (format #f "~a" (string-join v ","))))
+         (any-value
+          (lambda (v)
+            (if (list? v) (string-append "\"" (multi-value v) "\"") v)))
+         (key-value
+          (lambda (e)
+            (format #f "~a=~a" (car e) (any-value (cdr e))))))
+    (format #f "~a" (string-join (map key-value args) ","))))
+
+(define serialize-fail2ban-jail-action-configuration
+  (match-lambda
+    (($ <fail2ban-jail-action-configuration> _ name arguments)
+     (format
+      #f "~a~a"
+      name
+      (if (null? arguments) ""
+          (format
+           #f "[~a]"
+           (serialize-fail2ban-jail-action-configuration-arguments
+            arguments)))))))
+
+(define fail2ban-backend->string
+  (match-lambda
+    ('auto "auto")
+    ('pyinotify "pyinotify")
+    ('gamin "gamin")
+    ('polling "polling")
+    ('systemd "systemd")
+    (unknown
+     (leave (G_ "fail2ban: '~a' is not a supported backend~%") unknown))))
+
+(define fail2ban-log-encoding->string
+  (match-lambda
+    ('auto "auto")
+    ('utf-8 "utf-8")
+    ('ascii "ascii")
+    (unknown
+     (leave (G_ "fail2ban: '~a' is not a supported log encoding~%") unknown))))
+
+(define (fail2ban-jail-configuration-serialize-field-name name)
+  (cond ((symbol? name)
+         (fail2ban-jail-configuration-serialize-field-name
+          (symbol->string name)))
+        ((string-suffix? "?" name)
+         (fail2ban-jail-configuration-serialize-field-name
+          (string-drop-right name 1)))
+        ((string-prefix? "ban-time-" name)
+         (fail2ban-jail-configuration-serialize-field-name
+          (string-append "bantime." (substring name 9))))
+        ((string-contains name "-")
+         (fail2ban-jail-configuration-serialize-field-name
+          (string-filter (lambda (c) (equal? c #\-)) name)))
+        (else name)))
+
+(define (fail2ban-jail-configuration-serialize-string field-name value)
+  #~(string-append
+     #$(fail2ban-jail-configuration-serialize-field-name field-name)
+     " = " #$value "\n"))
+
+(define (fail2ban-jail-configuration-serialize-integer field-name value)
+  (fail2ban-jail-configuration-serialize-string
+   field-name (number->string value)))
+
+(define (fail2ban-jail-configuration-serialize-boolean field-name value)
+  (fail2ban-jail-configuration-serialize-string
+   field-name (if value "true" "false")))
+
+(define (fail2ban-jail-configuration-serialize-backend field-name value)
+  (if (maybe-value-set? value)
+      (fail2ban-jail-configuration-serialize-string
+       field-name (fail2ban-backend->string value))
+      ""))
+
+(define (fail2ban-jail-configuration-serialize-fail2ban-ignore-cache-configuration field-name value)
+  (fail2ban-jail-configuration-serialize-string
+   field-name (serialize-fail2ban-ignore-cache-configuration value)))
+
+(define (fail2ban-jail-configuration-serialize-fail2ban-jail-filter-configuration field-name value)
+  (fail2ban-jail-configuration-serialize-string
+   field-name (serialize-fail2ban-jail-filter-configuration value)))
+
+(define (fail2ban-jail-configuration-serialize-log-encoding field-name value)
+  (if (maybe-value-set? value)
+      (fail2ban-jail-configuration-serialize-string
+       field-name (fail2ban-log-encoding->string value))
+      ""))
+
+(define (fail2ban-jail-configuration-serialize-list-of-strings field-name value)
+  (if (null? value)
+      ""
+      (fail2ban-jail-configuration-serialize-string
+       field-name (string-join value " "))))
+
+(define (fail2ban-jail-configuration-serialize-list-of-fail2ban-jail-actions field-name value)
+  (if (null? value)
+      ""
+      (fail2ban-jail-configuration-serialize-string
+       field-name (string-join
+                   (map serialize-fail2ban-jail-action-configuration value) "\n"))))
+
+(define (fail2ban-jail-configuration-serialize-symbol field-name value)
+  (fail2ban-jail-configuration-serialize-string field-name (symbol->string value)))
+
+(define (fail2ban-jail-configuration-serialize-extra-content field-name value)
+  (if (maybe-value-set? value)
+      (string-append "\n" value "\n")
+      ""))
+
+(define-maybe integer (prefix fail2ban-jail-configuration-))
+(define-maybe string (prefix fail2ban-jail-configuration-))
+(define-maybe boolean (prefix fail2ban-jail-configuration-))
+(define-maybe symbol (prefix fail2ban-jail-configuration-))
+(define-maybe fail2ban-ignore-cache-configuration (prefix fail2ban-jail-configuration-))
+(define-maybe fail2ban-jail-filter-configuration (prefix fail2ban-jail-configuration-))
+
+(define-configuration fail2ban-jail-configuration
+  (name
+   string
+   "Required name of this jail configuration.")
+  (enabled?
+   (boolean #t)
+   "Whether this jail is enabled.")
+  (backend
+   maybe-symbol
+   "Backend to use to detect changes in the @code{ogpath}.  The default is
+'auto.  To consult the defaults of the jail configuration, refer to the
+@file{/etc/fail2ban/jail.conf} file of the @code{fail2ban} package."
+fail2ban-jail-configuration-serialize-backend)
+  (max-retry
+   maybe-integer
+   "The number of failures before a host get banned
+(e.g. @code{(max-retry 5)}).")
+  (max-matches
+   maybe-integer
+   "The number of matches stored in ticket (resolvable via
+tag @code{<matches>}) in action.")
+  (find-time
+   maybe-string
+   "The time window during which the maximum retry count must be reached for
+an IP address to be banned.  A host is banned if it has generated
+@code{max-retry} during the last @code{find-time}
+seconds (e.g. @code{(find-time \"10m\")}).  It can be provided in seconds or
+using Fail2Ban's \"time abbreviation format\", as described in @command{man 5
+jail.conf}.")
+  (ban-time
+   maybe-string
+   "The duration, in seconds or time abbreviated format, that a ban should last.
+(e.g. @code{(ban-time \"10m\")}).")
+  (ban-time-increment?
+   maybe-boolean
+   "Whether to consider past bans to compute increases to the default ban time
+of a specific IP address.")
+  (ban-time-factor
+   maybe-string
+   "The coefficient to use to compute an exponentially growing ban time.")
+  (ban-time-formula
+   maybe-string
+   "This is the formula used to calculate the next value of a ban time.")
+  (ban-time-multipliers
+   maybe-string
+   "Used to calculate next value of ban time instead of formula.")
+  (ban-time-max-time
+   maybe-string
+   "The maximum number of seconds a ban should last.")
+  (ban-time-rnd-time
+   maybe-string
+   "The maximum number of seconds a randomized ban time should last.  This can
+be useful to stop ``clever'' botnets calculating the exact time an IP address
+can be unbanned again.")
+  (ban-time-overall-jails?
+   maybe-boolean
+   "When true, it specifies the search of an IP address in the database should
+be made across all jails.  Otherwise, only the current jail of the ban IP
+address is considered.")
+  (ignore-self?
+   maybe-boolean
+   "Never ban the local machine's own IP address.")
+  (ignore-ip
+   (list-of-strings '())
+   "A list of IP addresses, CIDR masks or DNS hosts to ignore.
+@code{fail2ban} will not ban a host which matches an address in this list.")
+  (ignore-cache
+   maybe-fail2ban-ignore-cache-configuration
+   "Provide cache parameters for the ignore failure check.")
+  (filter
+   maybe-fail2ban-jail-filter-configuration
+   "The filter to use by the jail, specified via a
+@code{<fail2ban-jail-filter-configuration>} object.  By default, jails have
+names matching their filter name.")
+  (log-time-zone
+   maybe-string
+   "The default time zone for log lines that do not have one.")
+  (log-encoding
+   maybe-symbol
+   "The encoding of the log files handled by the jail.
+Possible values are: @code{'ascii}, @code{'utf-8} and @code{'auto}."
+fail2ban-jail-configuration-serialize-log-encoding)
+  (log-path
+   (list-of-strings '())
+   "The file names of the log files to be monitored.")
+  (action
+   (list-of-fail2ban-jail-actions '())
+   "A list of @code{<fail2ban-jail-action-configuration>}.")
+  (extra-content
+   maybe-string
+   "Extra content for the jail configuration."
+   fail2ban-jail-configuration-serialize-extra-content)
+  (prefix fail2ban-jail-configuration-))
+
+(define list-of-fail2ban-jail-configurations?
+  (list-of fail2ban-jail-configuration?))
+
+(define (serialize-fail2ban-jail-configuration config)
+  #~(string-append
+     #$(format #f "[~a]\n" (fail2ban-jail-configuration-name config))
+     #$(serialize-configuration
+      config fail2ban-jail-configuration-fields)))
+
+(define-configuration/no-serialization fail2ban-configuration
+  (fail2ban
+   (package fail2ban)
+   "The @code{fail2ban} package to use.  It is used for both binaries and as
+base default configuration that is to be extended with
+@code{<fail2ban-jail-configuration>} objects.")
+  (run-directory
+   (string "/var/run/fail2ban")
+   "The state directory for the @code{fail2ban} daemon.")
+  (jails
+   (list-of-fail2ban-jail-configurations '())
+   "Instances of @code{<fail2ban-jail-configuration>} collected from
+extensions.")
+  (extra-jails
+   (list-of-fail2ban-jail-configurations '())
+   "Instances of @code{<fail2ban-jail-configuration>} explicitly provided.")
+  (extra-content
+   maybe-string
+   "Extra raw content to add to the end of the @file{jail.local} file."))
+
+(define (serialize-fail2ban-configuration config)
+  (let* ((jails (fail2ban-configuration-jails config))
+         (extra-jails (fail2ban-configuration-extra-jails config))
+         (extra-content (fail2ban-configuration-extra-content config)))
+    (interpose
+     (append (map serialize-fail2ban-jail-configuration
+                  (append jails extra-jails))
+             (list (if (maybe-value-set? extra-content)
+                       extra-content
+                       ""))))))
+
+(define (config->fail2ban-etc-directory config)
+  (let* ((fail2ban (fail2ban-configuration-fail2ban config))
+         (jail-local (apply mixed-text-file "jail.local"
+                            (serialize-fail2ban-configuration config))))
+    (directory-union
+     "fail2ban-configuration"
+     (list (computed-file
+            "etc-fail2ban"
+            (with-imported-modules '((guix build utils))
+              #~(begin
+                  (use-modules (guix build utils))
+                  (let ((etc (string-append #$output "/etc")))
+                    (mkdir-p etc)
+                    (symlink #$(file-append fail2ban "/etc/fail2ban")
+                             (string-append etc "/fail2ban"))))))
+           (computed-file
+            "etc-fail2ban-jail.local"
+            (with-imported-modules '((guix build utils))
+              #~(begin
+                  (use-modules (guix build utils))
+                  (define etc/fail2ban (string-append #$output
+                                                      "/etc/fail2ban"))
+                  (mkdir-p etc/fail2ban)
+                  (symlink #$jail-local (string-append etc/fail2ban
+                                                       "/jail.local")))))))))
+
+(define (fail2ban-shepherd-service config)
+  (match-record config <fail2ban-configuration>
+    (fail2ban run-directory)
+    (let* ((fail2ban-server (file-append fail2ban "/bin/fail2ban-server"))
+           (pid-file (in-vicinity run-directory "fail2ban.pid"))
+           (socket-file (in-vicinity run-directory "fail2ban.sock"))
+           (config-dir (file-append (config->fail2ban-etc-directory config)
+                                    "/etc/fail2ban"))
+           (fail2ban-action (lambda args
+                              #~(lambda _
+                                  (invoke #$fail2ban-server
+                                          "-c" #$config-dir
+                                          "-p" #$pid-file
+                                          "-s" #$socket-file
+                                          "-b"
+                                          #$@args)))))
+
+      ;; TODO: Add 'reload' action.
+      (list (shepherd-service
+             (provision '(fail2ban))
+             (documentation "Run the fail2ban daemon.")
+             (requirement '(user-processes))
+             (modules `((ice-9 match)
+                        ,@%default-modules))
+             (start (fail2ban-action "start"))
+             (stop (fail2ban-action "stop")))))))
+
+(define fail2ban-service-type
+  (service-type (name 'fail2ban)
+                (extensions
+                 (list (service-extension shepherd-root-service-type
+                                          fail2ban-shepherd-service)))
+                (compose concatenate)
+                (extend (lambda (config jails)
+                          (fail2ban-configuration
+                           (inherit config)
+                           (jails (append (fail2ban-configuration-jails config)
+                                          jails)))))
+                (default-value (fail2ban-configuration))
+                (description "Run the fail2ban server.")))
+
+(define (fail2ban-jail-service svc-type jail)
+  "Convenience procedure to add a fail2ban service extension to SVC-TYPE, a
+<service-type> object.  The fail2ban extension is specified by JAIL, a
+<fail2ban-jail-configuration> object."
+  (service-type
+   (inherit svc-type)
+   (extensions
+    (append (service-type-extensions svc-type)
+            (list (service-extension fail2ban-service-type
+                                     (lambda _ (list jail))))))))
+
+
+;;;
+;;; Documentation generation.
+;;;
+(define (generate-doc)
+  (configuration->documentation 'fail2ban-configuration)
+  (configuration->documentation 'fail2ban-ignore-cache-configuration)
+  (configuration->documentation 'fail2ban-jail-action-configuration)
+  (configuration->documentation 'fail2ban-jail-configuration)
+  (configuration->documentation 'fail2ban-jail-filter-configuration))
diff --git a/gnu/tests/security.scm b/gnu/tests/security.scm
new file mode 100644
index 0000000000..ca6c857899
--- /dev/null
+++ b/gnu/tests/security.scm
@@ -0,0 +1,221 @@
+;;; GNU Guix --- Functional package management for GNU
+;;; Copyright © 2022 muradm <mail@muradm.net>
+;;;
+;;; This file is part of GNU Guix.
+;;;
+;;; GNU Guix is free software; you can redistribute it and/or modify it
+;;; under the terms of the GNU General Public License as published by
+;;; the Free Software Foundation; either version 3 of the License, or (at
+;;; your option) any later version.
+;;;
+;;; GNU Guix 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 General Public License for more details.
+;;;
+;;; You should have received a copy of the GNU General Public License
+;;; along with GNU Guix.  If not, see <http://www.gnu.org/licenses/>.
+
+(define-module (gnu tests security)
+  #:use-module (guix gexp)
+  #:use-module (gnu packages admin)
+  #:use-module (gnu services)
+  #:use-module (gnu services security)
+  #:use-module (gnu services ssh)
+  #:use-module (gnu system)
+  #:use-module (gnu system vm)
+  #:use-module (gnu tests)
+  #:export (%test-fail2ban-basic
+            %test-fail2ban-extension
+            %test-fail2ban-simple))
+
+
+;;;
+;;; fail2ban tests
+;;;
+
+(define-syntax-rule (fail2ban-test test-name test-os tests-more ...)
+  (lambda ()
+    (define os
+      (marionette-operating-system
+       test-os
+       #:imported-modules '((gnu services herd))))
+
+    (define vm
+      (virtual-machine
+       (operating-system os)
+       (port-forwardings '())))
+
+    (define test
+      (with-imported-modules '((gnu build marionette)
+                               (guix build utils))
+        #~(begin
+            (use-modules (srfi srfi-64)
+                         (gnu build marionette))
+
+            (define marionette (make-marionette (list #$vm)))
+
+            (test-runner-current (system-test-runner #$output))
+            (test-begin test-name)
+
+            (test-assert "fail2ban running"
+              (marionette-eval
+               '(begin
+                  (use-modules (gnu services herd))
+                  (start-service 'fail2ban))
+               marionette))
+
+            (test-assert "fail2ban socket ready"
+              (wait-for-unix-socket
+               "/var/run/fail2ban/fail2ban.sock" marionette))
+
+            (test-assert "fail2ban running after restart"
+              (marionette-eval
+               '(begin
+                  (use-modules (gnu services herd))
+                  (restart-service 'fail2ban))
+               marionette))
+
+            (test-assert "fail2ban socket ready after restart"
+              (wait-for-unix-socket
+               "/var/run/fail2ban/fail2ban.sock" marionette))
+
+            (test-assert "fail2ban pid ready"
+              (marionette-eval
+               '(file-exists? "/var/run/fail2ban/fail2ban.pid")
+               marionette))
+
+            (test-assert "fail2ban log file"
+              (marionette-eval
+               '(file-exists? "/var/log/fail2ban.log")
+               marionette))
+
+            tests-more ...
+
+            (test-end))))
+
+    (gexp->derivation test-name test)))
+
+(define run-fail2ban-basic-test
+  (fail2ban-test
+   "fail2ban-basic-test"
+
+   (simple-operating-system
+    (service fail2ban-service-type))))
+
+(define %test-fail2ban-basic
+  (system-test
+   (name "fail2ban-basic")
+   (description "Test basic fail2ban running capability.")
+   (value (run-fail2ban-basic-test))))
+
+(define %fail2ban-server-cmd
+  (program-file
+   "fail2ban-server-cmd"
+   #~(begin
+       (let ((cmd #$(file-append fail2ban "/bin/fail2ban-server")))
+         (apply execl cmd cmd `("-p" "/var/run/fail2ban/fail2ban.pid"
+                                "-s" "/var/run/fail2ban/fail2ban.sock"
+                                ,@(cdr (program-arguments))))))))
+
+(define run-fail2ban-simple-test
+  (fail2ban-test
+   "fail2ban-basic-test"
+
+   (simple-operating-system
+    (service fail2ban-service-type (fail2ban-configuration
+                                    (jails (list (fail2ban-jail-configuration
+                                                  (name "sshd")))))))
+
+   (test-equal "fail2ban sshd jail running status output"
+     '("Status for the jail: sshd"
+       "|- Filter"
+       "|  |- Currently failed:\t0"
+       "|  |- Total failed:\t0"
+       "|  `- File list:\t/var/log/secure"
+       "`- Actions"
+       "   |- Currently banned:\t0"
+       "   |- Total banned:\t0"
+       "   `- Banned IP list:\t"
+       "")
+     (marionette-eval
+      '(begin
+         (use-modules (ice-9 rdelim) (ice-9 popen) (rnrs io ports))
+         (let ((call-command
+                (lambda (cmd)
+                  (let* ((err-cons (pipe))
+                         (port (with-error-to-port (cdr err-cons)
+                                 (lambda () (open-input-pipe cmd))))
+                         (_ (setvbuf (car err-cons) 'block
+                                     (* 1024 1024 16)))
+                         (result (read-delimited "" port)))
+                    (close-port (cdr err-cons))
+                    (values result (read-delimited "" (car err-cons)))))))
+           (string-split
+            (call-command
+             (string-join (list #$%fail2ban-server-cmd "status" "sshd") " "))
+            #\newline)))
+      marionette))
+
+   (test-equal "fail2ban sshd jail running exit code"
+     0
+     (marionette-eval
+      '(status:exit-val (system* #$%fail2ban-server-cmd "status" "sshd"))
+      marionette))))
+
+(define %test-fail2ban-simple
+  (system-test
+   (name "fail2ban-simple")
+   (description "Test simple fail2ban running capability.")
+   (value (run-fail2ban-simple-test))))
+
+(define run-fail2ban-extension-test
+  (fail2ban-test
+   "fail2ban-extension-test"
+
+   (simple-operating-system
+    (service (fail2ban-jail-service openssh-service-type (fail2ban-jail-configuration
+                                                          (name "sshd") (enabled? #t)))
+             (openssh-configuration)))
+
+   (test-equal "fail2ban sshd jail running status output"
+     '("Status for the jail: sshd"
+       "|- Filter"
+       "|  |- Currently failed:\t0"
+       "|  |- Total failed:\t0"
+       "|  `- File list:\t/var/log/secure"
+       "`- Actions"
+       "   |- Currently banned:\t0"
+       "   |- Total banned:\t0"
+       "   `- Banned IP list:\t"
+       "")
+     (marionette-eval
+      '(begin
+         (use-modules (ice-9 rdelim) (ice-9 popen) (rnrs io ports))
+         (let ((call-command
+                (lambda (cmd)
+                  (let* ((err-cons (pipe))
+                         (port (with-error-to-port (cdr err-cons)
+                                 (lambda () (open-input-pipe cmd))))
+                         (_ (setvbuf (car err-cons) 'block
+                                     (* 1024 1024 16)))
+                         (result (read-delimited "" port)))
+                    (close-port (cdr err-cons))
+                    (values result (read-delimited "" (car err-cons)))))))
+           (string-split
+            (call-command
+             (string-join (list #$%fail2ban-server-cmd "status" "sshd") " "))
+            #\newline)))
+      marionette))
+
+   (test-equal "fail2ban sshd jail running exit code"
+     0
+     (marionette-eval
+      '(status:exit-val (system* #$%fail2ban-server-cmd "status" "sshd"))
+      marionette))))
+
+(define %test-fail2ban-extension
+  (system-test
+   (name "fail2ban-extension")
+   (description "Test extension fail2ban running capability.")
+   (value (run-fail2ban-extension-test))))