[torqueusers] Displaying X apps from a job

Troy Baer troy at osc.edu
Fri Feb 17 11:32:22 MST 2006

On Thu, 2006-02-16 at 15:02 -0700, John Hanks wrote:
> > 3.  The user is logging into the login node in an ssh session with X
> > forwarding enabled on the client side, and sshd either isn't creating an
> > X psuedo-display at all or is attaching the X pseudo-display to
> > localhost on the login node rather than a real IP address.  (This is
> > another odd default in recent OpenSSH releases.)  To disable that
> > behavior, set the following in /etc/ssh/sshd_config and restart sshd:
> > 
> > X11Forwarding yes
> > X11UseLocalhost no
> I think you've hit the nail on the head here. It smells like passing
> around localhost in my DISPLAY setting is the problem. Am I correct that
> I need a submitted job to send the display back to
> MASTER:ssh-tunnel-listening-for-X rather than localhost? I tried
> 'X11UseLocalhost no' but unfortunately that setting completely breaks X
> over ssh everywhere.

That's bizarre; it shouldn't hurt anything to set that.

Do your compute nodes have a default route out to the public network
(eg. using NAT on the login node)?  If not, I would try setting that.

Troy Baer                       troy at osc.edu
Science & Technology Support    http://www.osc.edu/hpc/
Ohio Supercomputer Center       614-292-9701

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