{ pkgs, lib, ... }: rec {
  calc = (import ((builtins.fetchTarball "https://gist.github.com/duairc/5c9bb3c922e5d501a1edb9e7b3b845ba/archive/3885f7cd9ed0a746a9d675da6f265d41e9fd6704.tar.gz") + "/net.nix" ) { inherit lib; }).lib.net;
  regex.ipv4 =
    let
      compRegex = "(25[0-5]|(2[0-4]|10|1?[1-9])?[0-9])";
    in
    "(${compRegex}\\.){3}${compRegex}";

  regex.cidr4 = "${regex.ipv4}/(3[0-2]|[1-2]?[0-9])";
  regex.ipOrCidr4 = "(${regex.ipv4}|${regex.cidr4})";
  ipv4ToInt = ipv4: calc.ip.diff ipv4 "0.0.0.0";
  intToipv4 = inte: calc.ip.add "0.0.0.0" inte; 
}