CLEAR VNC Usage and Troubleshooting
Introduction
Virtual Network Computing (VNC) allows you to securely access a graphical desktop session on the CLEAR systems from your local computer. This guide explains how to establish a VNC session using an SSH tunnel, connect to a remote desktop, and troubleshoot common connection issues.
Whether you are running engineering applications, graphical development tools, or desktop-based software, this guide will help you configure and maintain a secure VNC connection to the CLEAR environment.
CLEAR: Using VNC
Using VNC
NOTE: Before using VNC, make sure you have a CLEAR home directory. You can verify this by connecting to CLEAR through SSH using PuTTY or another SSH client. If you do not have a CLEAR home directory, please submit a help ticket requesting one.
VNC access to CLEAR uses an SSH tunnel to securely communicate between your local computer and the remote CLEAR system. You will first establish the SSH tunnel and then, while keeping the SSH connection open, use a VNC client to connect to your remote graphical desktop session.
Before proceeding, make note of the CLEAR system and VNC port number you will use. The same port number must be used when configuring both the SSH tunnel and your VNC client.
Available CLEAR Systems
The CLEAR environment includes the following systems. Depending on your course, application, or workload, you may be directed to use a specific host.
| CLEAR 8 Systems | CLEAR 9 Systems |
|---|---|
| borax.clear8.rice.edu | agate.clear9.rice.edu |
| cobalt.clear8.rice.edu | amber.clear9.rice.edu |
| opal.clear8.rice.edu | jade.clear9.rice.edu |
| onyx.clear9.rice.edu | |
| pyrite.clear9.rice.edu | |
| zorite.clear9.rice.edu |
Note: Use the CLEAR system and VNC port assigned or recommended for your course or application. Keep the same VNC port number throughout both the SSH tunnel and VNC client configuration.
Operating System Instructions
Refer to Installing and Configuring VNC Clients for instructions on different operating systems.
Keep your SSH tunnel open while using your VNC session. Closing the SSH connection will also interrupt the VNC connection.
CLEAR: VNC Problems
VNC Troubleshooting
If you experience problems connecting to CLEAR using VNC, review the following common issues.
SSH (PuTTY) cannot connect to the system:
Verify that you are using the correct CLEAR system name and that your network connection is working.
SSH authentication issue:
Verify that you are using your Rice NetID credentials and complete any required authentication prompts.
VNC Viewer cannot connect to the socket:
If you receive an error such as "Unable to connect to socket: Connection refused," verify that the same VNC port number is being used in both the SSH tunnel configuration and the VNC Viewer connection settings.
VNC Viewer refuses to connect:
You may already have a VNC session running on the CLEAR host. From your SSH session, you can check for an existing session using:
ps -ealf | grep vncconfig | grep <NetID>
Replace <NetID> with your Rice NetID. If an existing session is listed, verify whether it is still active before attempting to start another session.
VNC Viewer reports that DISPLAY is not set:
Windows users should verify that X11 forwarding and the SSH tunnel have been configured according to the VNC for Windows instructions.
Still Having Problems?
If the steps above do not resolve the issue, please submit a help ticket. Include as much information as possible, such as:
- The CLEAR system you are connecting to
- The VNC port number you are using
- Your local operating system
- The VNC client you are using
- Any error messages you received
- Screenshots, if available