[slurm-users] x11 forwarding not available?

[Jeffrey Frey]

Make sure you're using RSA keys in users' accounts -- we'd started setting-up ECDSA on-cluster keys as we built our latest cluster but libssh at that point didn't support them.  And since the Slurm X11 plugin is hard-coded to only use ~/.ssh/id_rsa, that further tied us to RSA.  It would be nice for the host and user key files to be configurable options; more configurable options for that plugin in general would be useful.




> On Oct 16, 2018, at 4:47 AM, Tina Friedrich <tina.friedrich at it.ox.ac.uk> wrote:
> 
> I had an issue getting x11 forwarding via SLURM (srun/sbatch) to work; ssh 
> worked fine. Tracked it down to the host name setting on the nodes; as per 
> RedHat/CentOS default, the hostname was set to the fully qualified. Turns out 
> SLURMs X11 forwarding doesn't work with that; setting the hostnames to the 
> short hostname made it all magically work. 
> 
> Tina
> 
> On Tuesday, 16 October 2018 09:29:01 BST Olivier Sallou wrote:
>> On 10/16/2018 01:07 AM, Dave Botsch wrote:
>>> Hi.
>>> 
>>> X11 forwarding is enabled and works for normal ssh.
>> 
>> I faced same issue, with ssh x11 working as expected on compute nodes,
>> but not with slurm -x11.
>> 
>> I patched slurm locally to make it work.
>> 
>> what you can try to see if it is the same issue:
>> 
>> 
>> srun -n1 --pty --x11 --pty bash
>> 
>> 
>> # xterm
>> // you should have an authorization failure error
>> 
>> // on connected node
>> # xauth list
>> 
>> you will have a list of MAGIC COOKIE like
>> 
>> myslurmmaster/unix:10  MIT-MAGIC-COOKIE-1  YYYYYY
>> myslurmnode/unix:52  MIT-MAGIC-COOKIE-1  XXXXXX
>> 
>> # echo $DISPLAY
>> localhost:52.0
>> 
>> 
>> To make it work manually I did (of course adapting node names and
>> display port number):
>> 
>> xauth remove myslurmnode/unix:52
>> xauth add localhost:52.0
>> 
>> then xterm (for example) worked.
>> 
>> If this is the same problem, slurm can be easilly patched to work (can
>> give you how)
>> 
>> Olivier
>> 
>>> Thanks.
>>> 
>>> On Mon, Oct 15, 2018 at 09:55:59PM +0000, Rhian Resnick wrote:
>>>> Double check /etc/ssh/sshd_config allows X11 forwarding on the node as it
>>>> is disable by default. (I think)
>>>> 
>>>> 
>>>> X11Forwarding yes
>>>> 
>>>> 
>>>> 
>>>> 
>>>> Rhian Resnick
>>>> 
>>>> Associate Director Research Computing
>>>> 
>>>> Enterprise Systems
>>>> 
>>>> Office of Information Technology
>>>> 
>>>> 
>>>> Florida Atlantic University
>>>> 
>>>> 777 Glades Road, CM22, Rm 173B
>>>> 
>>>> Boca Raton, FL 33431
>>>> 
>>>> Phone 561.297.2647
>>>> 
>>>> Fax 561.297.0222
>>>> 
>>>> [image] <https://hpc.fau.edu/wp-content/uploads/2015/01/image.jpg>
>>>> 
>>>> ________________________________
>>>> From: slurm-users <slurm-users-bounces at lists.schedmd.com> on behalf of
>>>> Dave Botsch <botsch at cnf.cornell.edu> Sent: Monday, October 15, 2018 5:51
>>>> PM
>>>> To: slurm-users at lists.schedmd.com
>>>> Subject: [slurm-users] x11 forwarding not available?
>>>> 
>>>> 
>>>> 
>>>> Wanted to test X11 forwarding. X11 forwarding works as a normal user
>>>> just ssh'ing to a node and running xterm/etc.
>>>> 
>>>> With srun, however:
>>>> 
>>>> srun -n1 --pty --x11 xterm
>>>> srun: error: Unable to allocate resources: X11 forwarding not available
>>>> 
>>>> So, what am I missing?
>>>> 
>>>> Thanks.
>>>> 
>>>> PS
>>>> 
>>>> srun --version
>>>> slurm 17.11.7
>>>> 
>>>> rpm -qa |grep slurm
>>>> ohpc-slurm-server-1.3.5-8.1.x86_64
>>>> ...
>>>> 
>>>> 
>>>> --
>>>> ********************************
>>>> David William Botsch
>>>> Programmer/Analyst
>>>> @CNFComputing
>>>> botsch at cnf.cornell.edu
>>>> ********************************
>>>> --
>>>> ********************************
>>>> David William Botsch
>>>> Programmer/Analyst
>>>> @CNFComputing
>>>> botsch at cnf.cornell.edu
>>>> ********************************
> 
> 
> -- 
> Tina Friedrich, Snr HPC Systems Administrator, Advanced Research Computing
> Research Computing and Support Services, Academic IT 
> IT Services, University of Oxford 
> http://www.arc.ox.ac.uk
> 


::::::::::::::::::::::::::::::::::::::::::::::::::::::
Jeffrey T. Frey, Ph.D.
Systems Programmer V / HPC Management
Network & Systems Services / College of Engineering
University of Delaware, Newark DE  19716
Office: (302) 831-6034  Mobile: (302) 419-4976
::::::::::::::::::::::::::::::::::::::::::::::::::::::