anchor.diff:      sha256 = "0knwnqsjwv7sa5wjb863ghabs7s269a73qwkmxpsbngjw9s0j2ih";
     };
   
  -  buildInputs = [ makeWrapper ];
  +  nativeBuildInputs = [ perl ];
   
     installPhase = ''
       mkdir -p $out/bin $out/share/man/man1
       cp nat-traverse $out/bin
       gzip -c nat-traverse.1 > $out/share/man/man1/nat-traverse.1.gz
  -    wrapProgram $out/bin/nat-traverse --prefix PATH : "${stdenv.lib.makeBinPath [ perl ]}"
     '';
   
     meta = with stdenv.lib; {
  
positive.code:       nat-traverse works out-of-the-box.
      '';
      homepage = https://www.speicherleck.de/iblech/nat-traverse/;
      license = stdenv.lib.licenses.gpl3Plus;
      platforms = stdenv.lib.platforms.all;
      maintainers = [ maintainers.iblech ];
    };
  }
  
negative.code: { stdenv, fetchurl, perl }:
  
  stdenv.mkDerivation rec {
    name = "nat-traverse-${version}";
  