anchor.diff:  { lib, stdenv, fetchurl, fetchpatch, autoreconfHook, removeReferencesTo
  -, file, openssl, perl, perlPackages, unzip, nettools, ncurses }:
  +, file, openssl, perl, perlPackages, nettools, gnused
  +, withPerlTools ? false }: let
   
  -stdenv.mkDerivation rec {
  +  perlWithPkgs = perl.withPackages (ps: with ps; [
  +    JSON
  +    TermReadKey
  +    Tk
  +  ]);
  +
  +in stdenv.mkDerivation rec {
     pname = "net-snmp";
     version = "5.9.1";
   
  
positive.code: 
    meta = with lib; {
      description = "Clients and server for the SNMP network monitoring protocol";
      homepage = "http://net-snmp.sourceforge.net/";
      license = licenses.bsd3;
      platforms = platforms.linux;
    };
  
negative.code:     substituteInPlace testing/fulltests/support/simple_TESTCONF.sh --replace "/bin/netstat" "${nettools}/bin/netstat"
    '';
  
    nativeBuildInputs = [ autoreconfHook nettools removeReferencesTo gnused file ];
    buildInputs = [ openssl ]
      ++ lib.optional withPerlTools perlWithPkgs;
  
    enableParallelBuilding = true;
    doCheck = false;  # tries to use networking
  