[bug#46851] [PATCH] services: Add endlessh service.

[Joshua Branson]

* gnu/services/ssh.scm: Add endlessh service
(<endlessh-configuration>): New record type.
(%default-endlessh): New variable.
(endlessh-shepherd-service, endlessh-service-type): New procedures.

doc: doc/guix.texi (Networking Services): New endlessh-service-type section.
---
 doc/guix.texi        | 24 ++++++++++++
 gnu/services/ssh.scm | 90 +++++++++++++++++++++++++++++++++++++++++++-
 2 files changed, 113 insertions(+), 1 deletion(-)

diff --git a/doc/guix.texi b/doc/guix.texi
index 27083f1ae6..bd6dbe5944 100644
--- a/doc/guix.texi
+++ b/doc/guix.texi
@@ -17081,6 +17081,30 @@ may cause undefined behaviour.
 @end table
 @end deftp
 
+@cindex Endlessh
+@deffn {Scheme Variable} endlessh-service-type
+This is the type for the @uref{https://github.com/skeeto/endlessh,
+Endlessh} program that delays ssh clients for days at a time by
+@emph{very slowly} sending a random and endless SSH banner.  The smart
+hacker will put endlessh running on port 22, and let crackers get stuck
+in this tarpit.  This lets your real ssh server run more securely on a
+non-standard port.
+
+@end deffn
+
+@deftp {Data Type} endlessh-configuration
+Data type representing the configuration for @code{endlessh-service}.
+@table @asis
+@item @code{package} (default: @var{endlessh})
+@code{endlessh} package to use.
+
+@item @code{config-file} (default: @var{"%default-endlessh-config-file"})
+The config file that endlessh should use.
+
+@end table
+@end deftp
+
+
 @cindex WebSSH
 @deffn {Scheme Variable} webssh-service-type
 This is the type for the @uref{https://webssh.huashengdun.org/, WebSSH}
diff --git a/gnu/services/ssh.scm b/gnu/services/ssh.scm
index 1891db0487..3f77627ae3 100644
--- a/gnu/services/ssh.scm
+++ b/gnu/services/ssh.scm
@@ -1,11 +1,12 @@
 ;;; GNU Guix --- Functional package management for GNU
-;;; Copyright ?? 2014, 2015, 2016, 2017, 2018, 2019 Ludovic Court??s 
<ludo@gnu.org>
+;;; Copyright ?? 2014, 2015, 2016, 2017, 2018, 2019, 2021 Ludovic Court??s 
<ludo@gnu.org>
 ;;; Copyright ?? 2016 David Craven <david@craven.ch>
 ;;; Copyright ?? 2016 Julien Lepiller <julien@lepiller.eu>
 ;;; Copyright ?? 2017 Cl??ment Lassieur <clement@lassieur.org>
 ;;; Copyright ?? 2019 Ricardo Wurmus <rekado@elephly.net>
 ;;; Copyright ?? 2020 pinoaffe <pinoaffe@airmail.cc>
 ;;; Copyright ?? 2020 Oleg Pykhalov <go.wigust@gmail.com>
+;;; Copyright ?? 2021 Joshua Branson <jbranso@dismail.de>
 ;;;
 ;;; This file is part of GNU Guix.
 ;;;
@@ -54,6 +55,11 @@
             autossh-configuration?
             autossh-service-type
 
+            endlessh-configuration
+            endlessh-configuration?
+            endlessh-service-type
+            %default-endlessh
+
             webssh-configuration
             webssh-configuration?
             webssh-service-type
@@ -739,6 +745,88 @@ object."
                              autossh-service-activation)))
    (default-value (autossh-configuration))))
 
+
+;;;
+;;; Endlessh
+;;;
+
+(define-record-type* <endlessh-configuration>
+  endlessh-configuration make-endlessh-configuration
+  endlessh-configuration?
+  (package     endlessh-configuration-package
+               (default endlessh))
+  (config-file endlessh-configuration-config-file
+               (default %default-endlessh-config-file)))
+
+(define %default-endlessh-config-file
+  (plain-file "endlessh.conf"
+              "# The port on which to listen for new SSH connections.
+Port 22
+
+# The endless banner is sent one line at a time. This is the delay
+# in milliseconds between individual lines.
+Delay 10000
+
+# The length of each line is randomized. This controls the maximum
+# length of each line. Shorter lines may keep clients on for longer if
+# they give up after a certain number of bytes.
+MaxLineLength 32
+
+# Maximum number of connections to accept at a time. Connections beyond
+# this are not immediately rejected, but will wait in the queue.
+MaxClients 4096
+
+# Set the detail level for the log.
+#   0 = Quiet
+#   1 = Standard, useful log messages
+#   2 = Very noisy debugging information
+LogLevel 0
+
+# Set the family of the listening socket
+#   0 = Use IPv4 Mapped IPv6 (Both v4 and v6, default)
+#   4 = Use IPv4 only
+#   6 = Use IPv6 only
+BindFamily 0"))
+
+(define endlessh-shepherd-service
+  (match-lambda
+    (($ <endlessh-configuration> package config-file)
+     (with-imported-modules (source-module-closure
+                             '((gnu build shepherd)
+                               ;; TODO add optional logging
+                               ;;(gnu system file-systems)
+                               ))
+       (list (shepherd-service
+              (documentation "Run the endlessh daemon.")
+              (provision '(endlessh))
+              (requirement '(networking))
+              (modules '((gnu build shepherd)
+                         ;; TODO add optional logging
+                         ;;(gnu system file-systems)
+                         ))
+              (start #~(make-forkexec-constructor/container
+                        (list #$(file-append package "/bin/endlessh")
+                              "-f" #$config-file)
+                        ;; TODO add optional logging
+                        ;; #:mappings (list (file-system-mapping
+                        ;;                   (source "/dev/log") ;for syslog
+                        ;;                   (target source)))
+                        ))
+              (stop #~(make-kill-destructor))))))))
+
+(define endlessh-service-type
+  (service-type
+   (name 'endlessh)
+   (description "Endlessh is an SSH tarpit that very slowly sends an endless,
+random SSH banner. It keeps SSH clients locked up for hours or even days at a
+time. The purpose is to put your real SSH server on another port and then let
+the script kiddies get stuck in this tarpit instead of bothering a real
+server.")
+   (extensions
+    (list (service-extension
+           shepherd-root-service-type endlessh-shepherd-service)))
+   (default-value (endlessh-configuration))))
+
 
 ;;;
 ;;; WebSSH
-- 
2.30.0