nixpkgs/nixos/modules/services/security/endlessh.nix

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2022-10-22 12:53:35 +00:00
{ 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 ];
}