mrtg: add ipv6-required perl packages

{ lib, stdenv, fetchurl, perl, gd, rrdtool }:

let

  perlWithPkgs = perl.withPackages (pp: with pp;[

    Socket6

    IOSocketINET6

  ]);

in

stdenv.mkDerivation rec {

  pname = "mrtg";

  version = "2.17.10";

  };

  buildInputs = [

    perl

    # add support for ipv6 snmp:

    # https://github.com/oetiker/mrtg/blob/433ebfa5fc043971b46a5cd975fb642c76e3e49d/src/bin/mrtg#L331-L341

    perlWithPkgs

    gd

    rrdtool

  ];