Listen only on the docker interface

src/dockerproxy.js

@@ -132,7 +132,7 @@ function start(callback) {
         .use(middleware.lastMile());
 
     gHttpServer = http.createServer(proxyServer);
-    gHttpServer.listen(constants.DOCKER_PROXY_PORT, '0.0.0.0', callback);
+    gHttpServer.listen(constants.DOCKER_PROXY_PORT, '172.18.0.1', callback);
 
     // Overwrite the default 2min request timeout. This is required for large builds for example
     gHttpServer.setTimeout(60 * 60 * 1000);