* Prevent tests from accessing the host's network accidentally. For

instance, `nixos-rebuild' in the installer test does a `nix-pull'
  from nixos.org.

svn path=/nixos/branches/boot-order/; revision=22325

modules/testing/test-instrumentation.nix

@@ -80,6 +80,10 @@ in
     # serial port).
     services.syslogd.extraConfig = "*.*,kern.none /dev/ttyS0";
 
+    # Prevent tests from accessing the Internet.
+    networking.defaultGateway = mkOverride 50 {} "";
+    networking.nameservers = mkOverride 50 {} [ ];
+
   };
 
 }