system/modules/network.nix

{ pkgs, ... }:
{
  networking.hostName = "launchpad"; # Define your hostname.
  # networking.wireless.enable = true;  # Enables wireless support via wpa_supplicant.

  # Configure network proxy if necessary
  # networking.proxy.default = "http://user:password@proxy:port/";
  # networking.proxy.noProxy = "127.0.0.1,localhost,internal.domain";
  networking.extraHosts = ''
  192.168.12.20   router.local
  192.168.12.21   switch.local
  192.168.12.25   dhcpd.local
  192.168.12.40   launchpad.local
  192.168.12.41   xeon.local
  192.168.12.80   robo.local
  192.168.12.81   nas.local
  192.168.12.83   homeassistant.local
  192.168.12.60   toons.local

  45.58.52.52     www
  172.245.111.249 est
  216.189.156.74  mail
  '';

  networking.interfaces.enp4s0.ipv4.addresses = [ {
    address = "192.168.12.40";
    prefixLength = 24;
  } ];
  networking.defaultGateway = "192.168.12.20";
  networking.nameservers = [ "192.168.12.25" ];
  networking.firewall = {
    allowedTCPPortRanges = [ { from = 35000; to = 36000; } { from = 5000; to = 6000; } { from = 8000; to = 9000; } ];
    extraCommands = ''iptables -t raw -A OUTPUT -p udp -m udp --dport 137 -j CT --helper netbios-ns'';
  };

  # Enable networking
  networking.networkmanager.enable = true;
}