[bug#39136] [PATCH] gnu: services: Add endlessh.

[anothersms@gmail.com (Nicolò Balzarotti)]

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Hello guix!

This is my first service :) I know I still miss documentation and tests,
but before diving into it I wanted a general feedback on it (so that if
we decide to change something I don't have to adjust the docs and the
tests twice).

Endlessh is already in the repo, but for those who don't know: it's a
fake ssh server; it should be used to prevent bruteforce attacks and the
like by "freezing" the connection on the standard port (while the real
ssh server is on another non-standard port).  So, I don't know if as
default port should be 22 or, as it is now, 2222 (program's default).

My second doubt is regarding the place; it's an ssh server, but its main
purpose is for security? Maybe should go under admin.scm? I'm not sure

Last thing: bind-family as a list of allowed values is a suggetion from
IRC @leoprikler. Thanks for your help there!

Waiting for your feedback,

Nicolò


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From 63f975ec47de8ab951beaac6781327faf06d0cac Mon Sep 17 00:00:00 2001
From: nixo <nicolo@nixo.xyz>
Date: Tue, 14 Jan 2020 22:08:15 +0100
Subject: [PATCH] gnu: services: Add endlessh.

* gnu/services/ssh.scm (endlessh): New variable.
---
 gnu/services/ssh.scm | 74 +++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 73 insertions(+), 1 deletion(-)

diff --git a/gnu/services/ssh.scm b/gnu/services/ssh.scm
index d2dbb8f80d..d2729fb059 100644
--- a/gnu/services/ssh.scm
+++ b/gnu/services/ssh.scm
@@ -45,7 +45,11 @@
             dropbear-configuration
             dropbear-configuration?
             dropbear-service-type
-            dropbear-service))
+            dropbear-service
+
+            endlessh-configuration
+            endlessh-configuration?
+            endlessh-service-type))
 
 ;;; Commentary:
 ;;;
@@ -628,4 +632,72 @@ daemon} with the given @var{config}, a @code{<dropbear-configuration>}
 object."
   (service dropbear-service-type config))
 
+\f
+;;;
+;;; Endlessh.
+;;;
+
+(define-record-type* <endlessh-configuration>
+  endlessh-configuration make-endlessh-configuration
+  endlessh-configuration?
+  ;; list of two symbols, allowed values are ipv4, ipv6 or both
+  (bind-family endlessh-configuration-bind-family (default '(ipv4 ipv6)))
+  ;; integer
+  (delay endlessh-configuration-delay (default 10000))
+  ;; integer
+  ;; Must be in the range
+  (length endlessh-configuration-length (default 32))
+  ;; integer
+  (max-clients endlessh-configuration-max-clients (default 4096))
+  ;; integer
+  (port-number endlessh-configuration-port-number (default 2222))
+  ;; integer
+  ;; Allowed values are 0, 1 and 2
+  (log-level endlessh-configuration-log-level (default 0)))
+
+(define (endlessh-config->conf config)
+  "Convert the CONFIG of type <endlessh-config> to a config file."
+  (let* ((family (endlessh-configuration-bind-family config))
+	 (ipv4 (member 'ipv4 family))
+	 (ipv6 (member 'ipv6 family))
+	 (port (endlessh-configuration-port-number config))
+	 (delay (endlessh-configuration-delay config))
+	 (length (endlessh-configuration-length config))
+	 (log-level (endlessh-configuration-log-level config))
+	 (max-clients (endlessh-configuration-max-clients config))
+	 (bind
+	  ;; check if both are true (0), or only one of them is present
+	  (if (not (and (equal? ipv4 ipv6) ipv4))
+	      (if ipv4 4
+		  (if ipv6 6
+		      (throw 'endlessh-error
+			     "bind-family must contain at least one value")))
+	      0)))
+    (mixed-text-file "endlessh.conf"
+		     "# Generated by 'endlessh-config'.\n\n"
+		     "Port " (number->string port) "\n"
+		     "Delay " (number->string delay) "\n"
+		     "MaxLineLength " (number->string length) "\n"
+		     "MaxClients " (number->string max-clients) "\n"
+		     "LogLevel " (number->string log-level) "\n"
+		     "BindFamily " (number->string bind) "\n")))
+
+(define (endlessh-shepherd-service config)
+  (shepherd-service
+   (documentation "Run endlessh tarpit server.")
+   (provision '(endlessh))
+   (start #~(make-forkexec-constructor
+	     (list #$(file-append endlessh "/bin/endlessh")
+		   "-f" #$(endlessh-config->conf config))))
+   (stop  #~(make-kill-destructor))))
+
+(define endlessh-service-type
+  (service-type
+   (name 'endlessh)
+   (description "Run endlessh tarpit server.")
+   (extensions
+    (list (service-extension shepherd-root-service-type
+                             (compose list endlessh-shepherd-service))))
+   (default-value (endlessh-configuration))))
+
 ;;; ssh.scm ends here
-- 
2.24.1