nix-configs/nixos-modules/dhcp.nix

{ config, lib, ... }:
{
  options = {
    mainInterfaceConfig = lib.mkOption {
      type = lib.types.str;
    };
  };
  config = {
    networking.firewall.allowedUDPPorts = [
      67
      68
    ];
    systemd.network.networks.${config.mainInterfaceConfig} = {
      networkConfig = {
        DHCPServer = true;
        IPv6SendRA = true;
      };
      dhcpServerConfig = {
        EmitDNS = true;
        PoolSize = 50;
        DNS = [
          "10.42.69.2"
          "10.42.69.100"
        ];
        EmitRouter = true;
        Router = "10.42.69.1";
        SendOption = [
          "15:string:icanttype.org"
          "119:string:icanttype.org"
        ];
      };
      ipv6SendRAConfig = {
        RouterLifetimeSec = 0;
        EmitDNS = false;
      };
      ipv6Prefixes = [ { Prefix = "fd72:3dd5:21ae:3c97::/64"; } ];
    };
  };
}