nixos-config/system/server/initssh.nix

{ config, lib, pkgs, ... }:

with lib;

let

  cfg = config.configuration.init-ssh;

in {

  options.configuration.init-ssh = {

    enable = mkOption {
      default = "disable";
      type = with types; enum [ "disable" "prepare" "enabled" ];
    };

    kernelModules = mkOption { type = with types; listOf str; };

    port = mkOption {
      default = 23;
      type = with types; int;
    };

    authorizedKeys = mkOption {
      type = with types; listOf str;
      default = config.users.users.root.openssh.authorizedKeys.keys
        ++ (map (keyFile: lib.fileContents keyFile)
          config.users.users.root.openssh.authorizedKeys.keyFiles);
    };
    hostECDSAKey = mkOption {
      default = null;
      type = with types; nullOr path;
      description = ''
        you only need one host key
        nix-shell -p dropbear --run "dropbearkey -t ecdsa -f ./host_ecdsa_key"
      '';
    };

  };

  config = mkMerge [

    (mkIf (cfg.enable != "disable") {
      services.tor = {
        enable = true;
        client.enable = true;
        hiddenServices.bootup.map = [{ port = 23; }];
      };
    })

    (mkIf (cfg.enable == "enabled") {

      # tor setup
      boot.initrd.secrets = {
        "/etc/tor/onion/bootup" = /var/lib/tor/onion/bootup;
      };

      boot.initrd.extraUtilsCommands = ''
        copy_bin_and_libs ${pkgs.tor}/bin/tor
      '';

      boot.initrd.network.postCommands = let
        torRc = (pkgs.writeText "tor.rc" ''
          DataDirectory /etc/tor
          SOCKSPort 127.0.0.1:9050 IsolateDestAddr
          SOCKSPort 127.0.0.1:9063
          HiddenServiceDir /etc/tor/onion/bootup
          HiddenServicePort ${toString cfg.port} 127.0.0.1:${toString cfg.port}
        '');
      in ''
        echo "tor: preparing onion folder"
        # have to do this otherwise tor does not want to start
        chmod -R 700 /etc/tor

        echo "make sure localhost is up"
        ip a a 127.0.0.1/8 dev lo
        # ifconfig lo up
        ip link set lo up

        echo "tor: starting tor"
        tor -f ${torRc} --verify-config
        tor -f ${torRc} &
      '';

      # ssh setup
      # todo add the ssh host fingerprint to your trusted stuff
      # todo set ssh host key here
      boot.initrd.network.enable = true;
      boot.initrd.network.ssh = {
        enable = true;
        authorizedKeys = cfg.authorizedKeys;
        port = cfg.port;
      };
      boot.initrd.availableKernelModules = cfg.kernelModules;
      boot.initrd.network.ssh.hostECDSAKey = cfg.hostECDSAKey;
    })
  ];
}