{ user ? throw "user argument is required" }: { ... }:

{
  networking.firewall = {
    allowedTCPPorts = [ 22000 ];
    allowedUDPPorts = [ 21027 22000 ];
  };

  home-manager.users.${user.name} = {
    services.syncthing = {
      enable = true;
      extraOptions = [ "-no-default-folder" ];
    };
  };
}