NixVM/nixos/modules/system/networking.nix

{
  config,
  ...
}: {
  networking = {
    hostName = "nixOS";
    networkmanager.enable = true;
  
    firewall = {
      enable = true;
      # allowedTCPPorts = [ 80 443];
      # allowedUDPPorts = [];
    };
  };
}