nyx/modules/nixos/networking/ssh.nix

{...}: {
  services.openssh = {
    enable = true;
    settings = {
      PermitRootLogin = "no";
      PasswordAuthentication = false;

      ClientAliveCountMax = 5;
      ClientAliveInterval = 60;
    };
    openFirewall = true;
    ports = [22];

    hostKeys = [
      {
        bits = 4096;
        path = "/etc/ssh/ssh_host_rsa_key";
        type = "rsa";
      }
      {
        bits = 4096;
        path = "/etc/ssh/ssh_host_ed25519_key";
        type = "ed25519";
      }
    ];
  };
}