Restricting the host where grid hub is listening if -host option is s…

…pecified. Fixes issue 4589

java/server/src/org/openqa/grid/web/Hub.java

@@ -54,6 +54,7 @@ public class Hub {
 
   private final int port;
   private final String host;
+  private final boolean isHostRestricted;
   private final Registry registry;
   private final Map<String, Class<? extends Servlet>> extraServlet = Maps.newHashMap();
 
@@ -77,9 +78,11 @@ public Hub(GridHubConfiguration config) {
 
     if (config.getHost() != null) {
       host = config.getHost();
+      isHostRestricted = true;
     } else {
       NetworkUtils utils = new NetworkUtils();
       host = utils.getIp4NonLoopbackAddressOfThisMachine().getHostAddress();
+      isHostRestricted = false;
     }
     this.port = config.getPort();
 
@@ -101,6 +104,9 @@ private void initServer() {
       server = new Server();
       SocketConnector socketListener = new SocketConnector();
       socketListener.setMaxIdleTime(60000);
+      if (isHostRestricted) {
+        socketListener.setHost(host);
+      }
       socketListener.setPort(port);
       server.addConnector(socketListener);