[slurm-users] SLURM 20.11.0 no x11 forwarding.

[Luis R. Torres]

Hi Folks,

I'm currently running a small but powerful 10 node cluster where we require
the scheduling of certain graphical apps.  Our SLURM version is 20.11.0,
half our nodes are RHEL7 and the other half Ubuntu 18.04.

Our slurm config related to x11 is:

PrologFlags=*x*11

*X*11Parameters=home_*x*authority

We get the following error when attempting to use forwarding using SLURM


srun --nodelist=node01 --x11 xeyes

X11 connection rejected because of wrong authentication.

Error: Can't open display: localhost:78.0

srun: error: node01: task 0: Exited with exit code 1

The steps we take are:
ssh -X user at login-node
[user at login-node]$ srun --nodelist=node01 --x11 xeyes

No user accounts are allowed to SSH directly into execution nodes, only a
few special user accounts, however, those accounts have issues when using
--x11 but have NO issues when connecting directly (and forwarding) to the
execution nodes.

We went through this group to determine if anyone else has had similar
issues resolved but I didn't find anything other than some
recommendations.  Has someone actually resolved this particular (or very
similar) issue?

Our sshd_config is as follows:

X11Forwarding yes

X11DisplayOffset 10

X11UseLocalhost no


Our cluster is configured with SlurmUser=slurm, not root.


Thanks,
-- 
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Luis R. Torres
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