anchor.diff:  
     nativeBuildInputs = [ pkg-config ];
     buildInputs = [ nettle libidn ]
  -    ++ optionals stdenv.isLinux [ dbus libnetfilter_conntrack ];
  +    ++ optionals dbusSupport [ dbus ]
  +    ++ optionals stdenv.isLinux [ libnetfilter_conntrack ];
   
     meta = {
       description = "An integrated DNS, DHCP and TFTP server for small networks";
  
positive.code: { lib, stdenv, fetchurl, pkg-config, dbus, nettle, fetchpatch
  , libidn, libnetfilter_conntrack, buildPackages }:
  
  with lib;
  let
    copts = concatStringsSep " " ([
      "-DHAVE_IDN"
      "-DHAVE_DNSSEC"
    ] ++ optionals stdenv.isLinux [
      "-DHAVE_DBUS"
      "-DHAVE_CONNTRACK"
    ]);
  in
  
negative.code:     substituteInPlace $out/Library/LaunchDaemons/uk.org.thekelleys.dnsmasq.plist \
        --replace "/usr/local/sbin" "$out/bin"
    '' + optionalString stdenv.isLinux ''
      install -Dm755 contrib/lease-tools/dhcp_lease_time $out/bin/dhcp_lease_time
      install -Dm755 contrib/lease-tools/dhcp_release $out/bin/dhcp_release
      install -Dm755 contrib/lease-tools/dhcp_release6 $out/bin/dhcp_release6
  
    '' + optionalString dbusSupport ''
      install -Dm644 dbus/dnsmasq.conf $out/share/dbus-1/system.d/dnsmasq.conf
      mkdir -p $out/share/dbus-1/system-services
      cat <<END > $out/share/dbus-1/system-services/uk.org.thekelleys.dnsmasq.service
      [D-BUS Service]
  