Installing and Configuring VNC Clients

Instructions and installing and configuring VNC client software on Windows, Linux, and macOS systems

Introduction

Before you can access a graphical desktop on the CLEAR systems using VNC, you must have a VNC client installed on your local computer. This guide provides information for preparing Windows, Linux, and macOS systems for VNC access to CLEAR.

VNC connections to CLEAR are established securely through an SSH tunnel. You will need your Rice NetID, the CLEAR system hostname, and the VNC port number you plan to use.

NOTE: For general instructions on selecting a CLEAR system and establishing a VNC connection, see the Using VNC guide.

VNC for Linux

Linux systems typically include an SSH client. You will also need a VNC viewer application, such as TigerVNC.

Establish the SSH Tunnel

Open a Terminal window and enter:

ssh -Y -L <Port>:localhost:<Port> <NetID>@<MachineName>

Replace:

  • <Port> with your selected VNC port number
  • <NetID> with your Rice NetID
  • <MachineName> with the CLEAR system hostname

Enter your Rice NetID password when prompted and complete Duo authentication if requested.

If the connection is successful, you should see a terminal session similar to the following:

Terminal showing a successful SSH connection to a CLEAR system

Start the VNC Viewer

Keep the SSH connection open. Start your VNC viewer using:

vncviewer localhost:<Port>

Replace <Port> with the same port number used when establishing the SSH tunnel.

When the VNC connection opens:

  1. Wait for the Linux desktop login window to appear.
  2. If an Authentication Required window appears before the login screen, select Cancel.
  3. Enter your Rice NetID in lowercase.
  4. Enter your Rice NetID password when prompted.
  5. Wait for the graphical desktop session to load.

VNC for Windows

Windows users need an SSH client and a VNC viewer application. The existing CLEAR VNC configuration uses PuTTY to establish the SSH tunnel and a VNC viewer such as TigerVNC to connect to the graphical desktop.

NOTE: If your configuration requires an X-Windows server, make sure it is running before starting your connection.

Configure the SSH Connection in PuTTY

  1. Open PuTTY.
  2. Select Session in the left-hand menu.
  3. Enter the CLEAR system hostname in Host Name (or IP address).
  4. Enter a descriptive name under Saved Sessions, such as amber vnc tunnel.
  5. Select Save.

PuTTY Session configuration showing the hostname and saved session fields

Configure the SSH Tunnel

  1. In PuTTY, expand Connection > SSH and select Tunnels.
  2. Enter your selected VNC port number in Source port.
  3. Enter localhost:<Port> in Destination, using the same VNC port number.
  4. Select Add.

PuTTY SSH tunnel configuration showing the source port and destination fields

If required for your configuration, select Connection > SSH > X11 and enable X11 forwarding.

Save the Configuration

  1. Return to Session.
  2. Select the saved session you created earlier.
  3. Select Save to save the tunnel configuration.

PuTTY configuration window showing the saved SSH tunnel configuration

Open the SSH Tunnel

  1. Select your saved PuTTY session.
  2. Select Load.
  3. Select Open.
  4. Enter your Rice NetID and password when prompted.
  5. Complete Duo authentication if requested.

PuTTY Session window showing the Load and Open buttons

After authentication, leave the PuTTY connection open. This connection provides the SSH tunnel used by your VNC client.

PuTTY terminal window showing an SSH login prompt

Connect with Your VNC Viewer

Open your VNC viewer and enter the following in the VNC Server field:

localhost:<Port>

Replace <Port> with the same VNC port number configured in PuTTY.

Select Connect. When the Linux desktop login window appears, enter your Rice NetID in lowercase and your Rice NetID password when prompted.

VNC for macOS

macOS includes a native SSH client. You will also need a VNC viewer application, such as TigerVNC.

Establish the SSH Tunnel

Open Terminal and enter:

ssh -Y -L <Port>:localhost:<Port> <NetID>@<MachineName>

Replace:

  • <Port> with your selected VNC port number
  • <NetID> with your Rice NetID
  • <MachineName> with the CLEAR system hostname

Enter your Rice NetID password when prompted and complete Duo authentication if requested.

If the connection is successful, you should see a terminal session similar to the following:

Terminal showing a successful SSH connection to a CLEAR system

Connect with Your VNC Viewer

Keep the Terminal SSH connection open and start your VNC viewer application.

Enter the following in the VNC Server field:

localhost:<Port>

Replace <Port> with the same port number used when establishing the SSH tunnel, and then select Connect.

When the Linux desktop login window appears:

  1. If an Authentication Required window appears before the login screen, select Cancel.
  2. Enter your Rice NetID in lowercase.
  3. Enter your Rice NetID password when prompted.
  4. Wait for the graphical desktop session to load.

VNC Troubleshooting

If you have problems establishing a VNC connection:

  • Verify that you are using the correct CLEAR system hostname.
  • Verify that the same VNC port number is used for both the SSH tunnel and the VNC viewer.
  • Make sure the SSH connection remains open while using VNC.
  • Verify that you completed Duo authentication successfully.

 


Keywords:
VNC, TigerVNC, RealVNC, Windows, Linux, macOS 
Doc ID:
162024
Owned by:
Amod U. in Rice U
Created:
2026-06-17
Updated:
2026-08-11
Sites:
Rice University