anchor.diff:    services.locate.enable = true;
     services.locate.includeStore = true;
     services.ntp.enable = false;
  +  services.nscd.enable = true; #caching daemon for DNS
  +  services.bind.enable = false;
  +  services.dnsmasq.enable = false;
   # Enable the OpenSSH daemon.
   
     services.openssh.enable = vbox1 == config.networking.hostName;
  
positive.code:         firewall.allowPing = false; #ipv6 ping is always allowed, src: https://nixos.org/releases/nixos/unstable/nixos-16.09pre79453.32b7b00/manual/index.html#sec-firewall
          enableWLAN = false;
          enableIPv6 = false;
  
          networkmanager.enable = false;
          wireless.enable = false;
          #XXX: Note: networking.networkmanager and networking.wireless can not be enabled at the same time: you can still connect to the wireless networks using NetworkManager. src: https://nixos.org/nixos/manual/index.html#sec-installation
        };
  # Select internationalisation properties.
        i18n = {
  
negative.code: nixpkgs.config = {
    allowUnfree = false;  # allow proprietary packages
      firefox.enableAdobeFlash = false;
      firefox.enableGoogleTalkPlugin = false;
    chromium.enablePepperFlash = false;
    packageOverrides = pkgs: {
  #qtcreator = pkgs.qtcreator.override { qt48 = pkgs.qt48Full; };
  #qemu = pkgs.qemu.override { spiceSupport = true; };
    };
  
    config.replaceStdenv = { pkgs }: pkgs.ccacheStdenv;
    config.packageOverrides = pkgs: {
      ccacheWrapper = pkgs.ccacheWrapper.override {
        extraConfig = ''
          export CCACHE_COMPRESS=0 CCACHE_NOCOMPRESS=1 CCACHE_COMPRESSLEVEL=0 CCACHE_BASEDIR=/tmp CCACHE_DIR=/ccache CCACHE_UMASK=0002 CCACHE_MAXSIZE=200G
          '';
      };
    };
  
  };
  
  
  