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Re: Parallel Computing Toolkit with ssh tunnels

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-

Also see


On Apr 14, 11:42 am, Art <grenan... at> 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: -R 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: 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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