HPC FAQ - X Windows

Supercomputer documentation is always a work in progress! Please email questions, corrections, or suggestions to the HPC support team at help-hpc@uky.edu as usual. Thanks!

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X Windows is ... See ssh.com and wikipedia.org/wiki/X-Windows.

Frequently Asked Questions

1. Why should I use X-Windows?


6. How do I login and run X applications?

It is important for security reasons to use an encrypted X session, so that others cannot see your private information, especially your password. You will tunnel or tunnel your X connection through ssh. This depends on the proper client settings

On Linux, your client may be configured globally by default to set up forwarded X connections, or you may override the default with the -X command-line flag, or you may specify the tunnel on a per-host basis in your own configuration file. See the man ssh page on your Linux workstation.

On MS-Windows clients there is often a check-box in the session setup for X forwarding. This may be on a global basis or a per-host basis.

For more info about forwarding X11 connections with ssh clients, such as puTTY, see http://www.tldp.org/HOWTO/XDMCP-HOWTO/ssh.html. Note: this is an off-site link and could disappear without notice.

7. How do I tell if my X connection is tunneled?

Check the DISPLAY variable to see if your X connection is being tunneled through ssh. If DISPLAY is set to a cluster node's IP number instead of your local workstation's IP number, then the connection is being tunneled. Use the command echo DISPLAY while connected to the cluster with X.

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