{ pkgs, lib, config, machines, ... }:
let
  inherit (config.security) gnupg;
  inherit (config.users) users;
in
{
systemd.services.ssh-mermet-reverse = {
  after = [ "network-online.target" ];
  wantedBy = [ "multi-user.target" ];
  serviceConfig = {
    Type = "simple";
    # Require services.openssh.gatewayPorts = "clientspecified";
    # on the target.
    ExecStart = ''${pkgs.openssh}/bin/ssh -v -g -N -T \
      -o ServerAliveInterval=10 \
      -o ExitOnForwardFailure=yes \
      -R *:10022:localhost:22 \
      ${machines.mermet.extraArgs.ipv4}
    '';
    Restart = "always";
    RestartSec = "5s";
  };
};
boot.initrd.network.ssh = {
  enable = true;
  port = 2222;
  authorizedKeys = users.root.openssh.authorizedKeys.keys;
  hostKeys = [ "/root/initrd/ssh.key" ];
};
programs.ssh = {
  extraConfig = ''
    Compression = yes
  '';
};
services.upnpc.redirections = [
  { port = 22; protocol = "TCP"; } # SSH
  { port = 2222; protocol = "TCP"; }  # SSH (boot)
  { port = 60000; protocol = "UDP"; } # Mosh
  { port = 60001; protocol = "UDP"; } # Mosh
  { port = 60002; protocol = "UDP"; } # Mosh
  { port = 60003; protocol = "UDP"; } # Mosh
];
}