nixos/endlessh: init module

nixos/doc/manual/from_md/release-notes/rl-2211.section.xml

···
       </listitem>
       <listitem>
         <para>
+          <link xlink:href="https://github.com/skeeto/endlessh">endlessh</link>,
+          an SSH tarpit. Available as
+          <link linkend="opt-services.endlessh.enable">services.endlessh</link>.
+        </para>
+      </listitem>
+      <listitem>
+        <para>
           <link xlink:href="https://github.com/shizunge/endlessh-go">endlessh-go</link>,
           an SSH tarpit that exposes Prometheus metrics. Available as
           <link linkend="opt-services.endlessh-go.enable">services.endlessh-go</link>.

nixos/doc/manual/release-notes/rl-2211.section.md

···
 
 - [alps](https://git.sr.ht/~migadu/alps), a simple and extensible webmail. Available as [services.alps](#opt-services.alps.enable).
 
+- [endlessh](https://github.com/skeeto/endlessh), an SSH tarpit. Available as [services.endlessh](#opt-services.endlessh.enable).
+
 - [endlessh-go](https://github.com/shizunge/endlessh-go), an SSH tarpit that exposes Prometheus metrics. Available as [services.endlessh-go](#opt-services.endlessh-go.enable).
 
 - [netbird](https://netbird.io), a zero configuration VPN.

nixos/modules/module-list.nix

···
   ./services/security/certmgr.nix
   ./services/security/cfssl.nix
   ./services/security/clamav.nix
+  ./services/security/endlessh.nix
   ./services/security/endlessh-go.nix
   ./services/security/fail2ban.nix
   ./services/security/fprintd.nix

nixos/modules/services/security/endlessh.nix

···
+{ config, lib, pkgs, ... }:
+
+with lib;
+
+let
+  cfg = config.services.endlessh;
+in
+{
+  options.services.endlessh = {
+    enable = mkEnableOption (mdDoc "endlessh service");
+
+    port = mkOption {
+      type = types.port;
+      default = 2222;
+      example = 22;
+      description = mdDoc ''
+        Specifies on which port the endlessh daemon listens for SSH
+        connections.
+
+        Setting this to `22` may conflict with {option}`services.openssh`.
+      '';
+    };
+
+    extraOptions = mkOption {
+      type = with types; listOf str;
+      default = [ ];
+      example = [ "-6" "-d 9000" "-v" ];
+      description = mdDoc ''
+        Additional command line options to pass to the endlessh daemon.
+      '';
+    };
+
+    openFirewall = mkOption {
+      type = types.bool;
+      default = false;
+      description = lib.mdDoc ''
+        Whether to open a firewall port for the SSH listener.
+      '';
+    };
+  };
+
+  config = mkIf cfg.enable {
+    systemd.services.endlessh = {
+      description = "SSH tarpit";
+      requires = [ "network.target" ];
+      wantedBy = [ "multi-user.target" ];
+      serviceConfig =
+        let
+          needsPrivileges = cfg.port < 1024;
+          capabilities = [ "" ] ++ optionals needsPrivileges [ "CAP_NET_BIND_SERVICE" ];
+          rootDirectory = "/run/endlessh";
+        in
+        {
+          Restart = "always";
+          ExecStart = with cfg; concatStringsSep " " ([
+            "${pkgs.endlessh}/bin/endlessh"
+            "-p ${toString port}"
+          ] ++ extraOptions);
+          DynamicUser = true;
+          RootDirectory = rootDirectory;
+          BindReadOnlyPaths = [ builtins.storeDir ];
+          InaccessiblePaths = [ "-+${rootDirectory}" ];
+          RuntimeDirectory = baseNameOf rootDirectory;
+          RuntimeDirectoryMode = "700";
+          AmbientCapabilities = capabilities;
+          CapabilityBoundingSet = capabilities;
+          UMask = "0077";
+          LockPersonality = true;
+          MemoryDenyWriteExecute = true;
+          NoNewPrivileges = true;
+          PrivateDevices = true;
+          PrivateTmp = true;
+          PrivateUsers = !needsPrivileges;
+          ProtectClock = true;
+          ProtectControlGroups = true;
+          ProtectHome = true;
+          ProtectHostname = true;
+          ProtectKernelLogs = true;
+          ProtectKernelModules = true;
+          ProtectKernelTunables = true;
+          ProtectSystem = "strict";
+          ProtectProc = "noaccess";
+          ProcSubset = "pid";
+          RemoveIPC = true;
+          RestrictAddressFamilies = [ "AF_INET" "AF_INET6" ];
+          RestrictNamespaces = true;
+          RestrictRealtime = true;
+          RestrictSUIDSGID = true;
+          SystemCallArchitectures = "native";
+          SystemCallFilter = [ "@system-service" "~@resources" "~@privileged" ];
+        };
+    };
+
+    networking.firewall.allowedTCPPorts = with cfg;
+      optionals openFirewall [ port ];
+  };
+
+  meta.maintainers = with maintainers; [ azahi ];
+}

nixos/tests/all-tests.nix

···
   ejabberd = handleTest ./xmpp/ejabberd.nix {};
   elk = handleTestOn ["x86_64-linux"] ./elk.nix {};
   emacs-daemon = handleTest ./emacs-daemon.nix {};
+  endlessh = handleTest ./endlessh.nix {};
   endlessh-go = handleTest ./endlessh-go.nix {};
   engelsystem = handleTest ./engelsystem.nix {};
   enlightenment = handleTest ./enlightenment.nix {};

nixos/tests/endlessh.nix

···
+import ./make-test-python.nix ({ lib, pkgs, ... }:
+{
+  name = "endlessh";
+  meta.maintainers = with lib.maintainers; [ azahi ];
+
+  nodes = {
+    server = { ... }: {
+      services.endlessh = {
+        enable = true;
+        openFirewall = true;
+      };
+
+      specialisation = {
+        unprivileged.configuration.services.endlessh.port = 2222;
+
+        privileged.configuration.services.endlessh.port = 22;
+      };
+    };
+
+    client = { pkgs, ... }: {
+      environment.systemPackages = with pkgs; [ curl netcat ];
+    };
+  };
+
+  testScript = ''
+    def activate_specialisation(name: str):
+        server.succeed(f"/run/booted-system/specialisation/{name}/bin/switch-to-configuration test >&2")
+
+    start_all()
+
+    with subtest("Unprivileged"):
+        activate_specialisation("unprivileged")
+        server.wait_for_unit("endlessh.service")
+        server.wait_for_open_port(2222)
+        client.succeed("nc -dvW5 server 2222")
+
+    with subtest("Privileged"):
+        activate_specialisation("privileged")
+        server.wait_for_unit("endlessh.service")
+        server.wait_for_open_port(22)
+        client.succeed("nc -dvW5 server 22")
+  '';
+})

pkgs/servers/endlessh/default.nix

···
-{ lib, stdenv, fetchFromGitHub }:
+{ lib
+, stdenv
+, fetchFromGitHub
+, testers
+, endlessh
+, nixosTests
+}:
 
 stdenv.mkDerivation rec {
   pname = "endlessh";
···
     owner = "skeeto";
     repo = pname;
     rev = version;
-    sha256 = "0ziwr8j1frsp3dajr8h5glkm1dn5cci404kazz5w1jfrp0736x68";
+    hash = "sha256-yHQzDrjZycDL/2oSQCJjxbZQJ30FoixVG1dnFyTKPH4=";
   };
 
   makeFlags = [ "PREFIX=$(out)" ];
 
+  passthru.tests = {
+    inherit (nixosTests) endlessh;
+    version = testers.testVersion {
+      package = endlessh;
+      command = "endlessh -V";
+    };
+  };
+
   meta = with lib; {
     description = "SSH tarpit that slowly sends an endless banner";
     homepage = "https://github.com/skeeto/endlessh";
     changelog = "https://github.com/skeeto/endlessh/releases/tag/${version}";
     license = licenses.unlicense;
-    maintainers = [ maintainers.marsam ];
+    maintainers = with maintainers; [ azahi marsam ];
     platforms = platforms.unix;
   };
 }