[slurm-users] x11 forwarding not available?

[Dave Botsch]

At least by itself, switching to rsa keys did not fix it.

Used ssh-keygen to create an RSA key and edited .ssh/config to point to
that instead of to the dsa key. So unless srun is bypassing that
.ssh/config... nope.

On Tue, Oct 16, 2018 at 09:04:05AM -0400, Jeffrey Frey wrote:
> 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
> ::::::::::::::::::::::::::::::::::::::::::::::::::::::
> 
> 
> 
> 
> 

-- 
********************************
David William Botsch
Programmer/Analyst
@CNFComputing
botsch at cnf.cornell.edu
********************************