{ pkgs, config, lib, ... }: {
  networking.firewall = {
    enable = true;

    # Open ports in the firewall.
    allowedTCPPorts = [ ];
    allowedUDPPorts = [ 51820 ];
    allowedTCPPortRanges = [{
      from = 1714;
      to = 1764;
    }];
    allowedUDPPortRanges = [{
      from = 1714;
      to = 1764;
    }];

    # if packets are still dropped, they will show up in dmesg
    logReversePathDrops = true;
    # wireguard trips rpfilter up https://nixos.wiki/wiki/WireGuard#Setting_up_WireGuard_with_NetworkManager
    extraCommands = ''
      ip46tables -t mangle -I nixos-fw-rpfilter -p udp -m udp --sport 51820 -j RETURN
      ip46tables -t mangle -I nixos-fw-rpfilter -p udp -m udp --dport 51820 -j RETURN
    '';
    extraStopCommands = ''
      ip46tables -t mangle -D nixos-fw-rpfilter -p udp -m udp --sport 51820 -j RETURN || true
      ip46tables -t mangle -D nixos-fw-rpfilter -p udp -m udp --dport 51820 -j RETURN || true
    '';
  };

}