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Re: Parallel Computing Toolkit with ssh tunnels

  • To: mathgroup at smc.vnet.net
  • Subject: [mg87947] Re: Parallel Computing Toolkit with ssh tunnels
  • From: Sascha Kratky <skratky at gmail.com>
  • Date: Mon, 21 Apr 2008 03:24:09 -0400 (EDT)
  • References: <ftv8uf$7qj$1@smc.vnet.net>

Hi Art,

in order for SSH tunneling to work for your configuration, you have to
use active MathLink connections that use standard input and output as
MathLink transport, i.e.,

LaunchSlave["remotehost","ssh `1` math -mathlink", ConnectionType-
>LinkLaunch]

Also see http://documents.wolfram.com/applications/parallel/Configuration/Un=
ix.html

Regards,
Sascha

On Apr 14, 11:42 am, Art <grenan... at gmail.com> wrote:
> I would like to create a poor man's parallel cluster using PCT to work
> through ssh tunnels due circumvent firewall restrictions.
>
> I have 3 slave and 1 master linux machines with sshd running on port
> 22 and no other ports open. Assume each machine is additionally behind
> a physical firewall and has a local IP and the firewall port forwards
> 22 to this machine. Authentication is set up without a password so
> that the following works:
>
> me@master: ssh slave1 math
> Mathematica 6.0 for Linux x86 (64-bit)
> Copyright 1988-2008 Wolfram Research, Inc.
>
> In[1]:=
>
> I haven't been able to get LaunchSlave[] to work with this setup with
> various combinations of LinkName, LinkHost and for example, 'ssh -R
> port1:127.0.0.1:port1 -R port2:127.0.0.1:port2' as replacement for
> $RemoteCommand.
>
> It seems for each launch, the master listens on two new random ports
> for each slave and instructs the slave to connect to these ports on a
> specific IP. I think I have both an issue with the firewall and the
> fact that meaningless local IPs are passed to the slaves rather than
> the IP of the firewall. Even when I hand set the ports and open them
> on the firewalls, I have problems.
>
> I am guessing the mathlink connection protocol is the same as
> launching a remote kernel on a slave from the master, which I also
> haven't been able to get to work with these firewalls and port
> restrictions. I have been able to get it to work with all machines in
> one local network and with no firewall restrictions. I have also been
> able to use gdb to debug mathlink code using the  similar two port
> communication.
>
> I was wondering if anyone has gotten either PCT or remote kernel
> launching through ssh tunnels to work. There are prior posts on this
> forum and help on a wiki page:http://tinyurl.com/5ano5tbut I haven't
> been able to get them to work either. I am using 6.0.2 on 64-bit
> Ubuntu 7.10 with PCT 2.1.
>
> Thanks,
> Art.



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