[Paraview] paraview - client-server

burlen burlen.loring at gmail.com
Mon Feb 8 22:22:44 EST 2010


Thanks Pat, that makes sense, I'll try it out.

pat marion wrote:
> Actually I didn't write the notes at the hpc.mil <http://hpc.mil> link.
>
> Here is something- and maybe this is the problem that Sean refers to- 
> in some cases, when I have set up a reverse ssh tunnel from login node 
> to workstation (command executed from workstation) then the forward 
> does not work when the compute node connects to the login node.  
> However, if I have the compute node connect to the login node on port 
> 33333, then use portfwd to forward that to localhost:11111, where the 
> ssh tunnel is listening on port 11111, it works like a charm.  The 
> portfwd tricks it into thinking the connection is coming from 
> localhost and allow the ssh tunnel to work.  Hope that made a little 
> sense...
>
> Pat
>
> On Mon, Feb 8, 2010 at 6:29 PM, burlen <burlen.loring at gmail.com 
> <mailto:burlen.loring at gmail.com>> wrote:
>
>     Nice, thanks for the clarification. I am guessing that your
>     example should probably be the recommended approach rather than
>     the portfwd method suggested on the PV wiki. :) I took the
>     initiative to add it to the Wiki. KW let me know if this is not
>     the case!
>
>      
>     http://paraview.org/Wiki/Reverse_connection_and_port_forwarding#Reverse_connection_over_an_ssh_tunnel
>
>     Would you mind taking a look to be sure I didn't miss anything or
>     bollix it up?
>
>     The sshd config options you mentioned may be why your method
>     doesn't work on the Pleiades system, either that or there is a
>     firewall between the front ends and compute nodes. In either case
>     I doubt the NAS sys admins are going to reconfigure for me :) So
>     at least for now I'm stuck with the two hop ssh tunnels and
>     interactive batch jobs. if there were someway to script the ssh
>     tunnel in my batch script I would be golden...
>
>     By the way I put the details of the two hop ssh tunnel on the wiki
>     as well, and a link to Pat's hpc.mil <http://hpc.mil> notes. I
>     don't dare try to summarize them since I've never used portfwd and
>     it refuses to compile both on my workstation and the cluster.
>
>     Hopefully putting these notes on the Wiki will save future
>     ParaView users some time and headaches.
>
>
>     Sean Ziegeler wrote:
>
>         Not quite- the pvsc calls ssh with both the tunnel options and
>         the commands to submit the batch job.  You don't even need a
>         pvsc; it just makes the interface fancier.  As long as you or
>         PV executes something like this from your machine:
>         ssh -R XXXX:localhost:YYYY remote_machine submit_my_job.sh
>
>         This means that port XXXX on remote_machine will be the port
>         to which the server must connect.  Port YYYY (e.g., 11111) on
>         your client machine is the one on which PV listens.  You'd
>         have to tell the server (in the batch submission script, for
>         example) the name of the node and port XXXX to which to connect.
>
>         One caveat that might be causing you problems, port forwarding
>         (and "gateway ports" if the server is running on a different
>         node than the login node) must be enabled in the
>         remote_machine's sshd_config.  If not, no ssh tunnels will
>         work at all (see: man ssh and man sshd_config).  That's
>         something that an administrator would need to set up for you.
>
>         On 02/08/10 12:26, burlen wrote:
>
>             So to be sure about what you're saying: Your .pvsc script
>             ssh's to the
>             front end and submits a batch job which when it's
>             scheduled , your batch
>             script creates a -R style tunnel and starts pvserver using
>             PV reverse
>             connection. ? or are you using portfwd or a second ssh
>             session to
>             establish the tunnel ?
>
>             If you're doing this all from your .pvsc script without a
>             second ssh
>             session and/or portfwd that's awesome! I haven't been able
>             to script
>             this, something about the batch system prevents the tunnel
>             created
>             within the batch job's ssh session from working. I don't
>             know if that's
>             particular to this system or a general fact of life about
>             batch systems.
>
>             Question: How are you creating the tunnel in your batch
>             script?
>
>             Sean Ziegeler wrote:
>
>                 Both ways will work for me in most cases, i.e. a
>                 "forward" connection
>                 with ssh -L or a reverse connection with ssh -R.
>
>                 However, I find that the reverse method is more
>                 scriptable. You can
>                 set up a .pvsc file that the client can load and will
>                 call ssh with
>                 the appropriate options and commands for the remote
>                 host, all from the
>                 GUI. The client will simply wait for the reverse
>                 connection from the
>                 server, whether it takes 5 seconds or 5 hours for the
>                 server to get
>                 through the batch queue.
>
>                 Using the forward connection method, if the server
>                 isn't started soon
>                 enough, the client will attempt to connect and then
>                 fail. I've always
>                 had to log in separately, wait for the server to start
>                 running, then
>                 tell my client to connect.
>
>                 -Sean
>
>                 On 02/06/10 12:58, burlen wrote:
>
>                     Hi Pat,
>
>                     My bad. I was looking at the PV wiki, and thought
>                     you were talking about
>                     doing this without an ssh tunnel and using only
>                     port forward and
>                     paraview's --reverse-connection option . Now that
>                     I am reading your
>                     hpc.mil <http://hpc.mil> post I see what you mean :)
>
>                     Burlen
>
>
>                     pat marion wrote:
>
>                         Maybe I'm misunderstanding what you mean by
>                         local firewall, but
>                         usually as long as you can ssh from your
>                         workstation to the login node
>                         you can use a reverse ssh tunnel.
>
>
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