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Parallel Computing Toolkit with ssh tunnels

  • To: mathgroup at smc.vnet.net
  • Subject: [mg87599] Parallel Computing Toolkit with ssh tunnels
  • From: Art <grenander at gmail.com>
  • Date: Mon, 14 Apr 2008 05:42:54 -0400 (EDT)

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/5ano5t but 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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