This is the first time I've ever tried to use openmpi on more than a single machine. I have two identical machines running 12.3 x64 KDE, connected to a Gb switch (attached to a router, a telco router, and then the internet) and I want to do openmpi things between these two machines. My main question is how to make sure they can talk to each other - so, what ports need to be opened in the firewalls? Is it just SSH? (I *think* I saw that default openmpi uses SSH). I have SSHD running on both machines, along with firewall "allowed services" of Samba server, samba client, and SSH (in YaST). In Dolphin, when I click on Network (in Places) I see the workgroup name (whenever both machines are on).

# hosts         This file describes a number of hostname-to-address
#               mappings for the TCP/IP subsystem.  It is mostly
#               used at boot time, when no name servers are running.
#               On small systems, this file can be used instead of a
#               "named" name server.
# Syntax:
# IP-Address  Full-Qualified-Hostname  Short-Hostname
#    localhost

# special IPv6 addresses
::1             localhost ipv6-localhost ipv6-loopback

fe00::0         ipv6-localnet

ff00::0         ipv6-mcastprefix
ff02::1         ipv6-allnodes
ff02::2         ipv6-allrouters
ff02::3         ipv6-allhosts
I think this may be more than is necessary to get openmpi talking across the Gb switch... Can somebody take a look and mention any problems I might have due to settings I don't (yet) know about? I will be running openmpi software from the command line (with shell scripts, not using a batch scheduler.) I think I'll be using the built-in OpenMPI for 12.3, but may occasionally use MPICH2 self-compiled in /usr/local/...

Thanks in advance,