Changes

If you want to use the insecure access methods (and I still strongly recommend you use the secure method) and are certain that remote access will always take place within the context of a secure internal local area network then it is important to be aware that you must configure the CentOS firewall to allow this to happen. By default, the CentOS firewall is both enabled and configured to block insecure remote desktop access. Before proceeding, therefore, it is necessary to allow VNC traffic to pass uneventfully through the firewall. Before performing this task it is important to know that the remote desktop system uses TCP/IP port 5900 to access the screen 0 (the main screen of your desktop) for communicating between the client and server systems. We must, therefore, configure the firewall to allow traffic on this port. To achieve this simply perform the following steps:

2. Select the Other Ports option and click on the Add button to open the Add Port dialog.