On Nov 5, 2009, at 11:28 AM, Lee Amy wrote:
> I remembered MPI does not count on TCP/IP but why default iptables
> will prevent the MPI programs from running? After I stop iptables then
> programs run well. I use Ethernet as connection.
Note that Open MPI *can* use TCP as an interface for MPI messaging.
It definitely uses TCP for administrative control of MPI jobs, even if
TCP is not used for MPI messaging. Open MPI therefore basically
requires the ability to open sockets between all nodes in the job on
random TCP ports.
Your could probably configure iptables to "trust" all the machines in
your cluster (i.e., allow TCP sockets to/from random ports) but
disallow most (all?) TCP connections from outside your cluster, if you