I see. Thanks!
After carefully reading the following FAQ item
http://www.open-mpi.org/faq/?category=rsh#ssh-keys ,
I realized that mpirun of Open MPI does not work in a simple "master to slaves"
way,
while "slaves to slaves" is also possible.
Therefore, a same private key with a passphrase on all the nodes,
or hostbased authentication may be a more convenient way.
--
yumenlj
-----Original Message-----
From: Reuti <re...@staff.uni-marburg.de>
To: Open MPI Users <us...@open-mpi.org>
Sent: Thu, Mar 14, 2013 5:14 pm
Subject: Re: [OMPI users] a problem about mpirun and SSH when using Open MPI
1.7rc8
Hi,
Am 14.03.2013 um 09:20 schrieb yumenlj:
> Hi, all
>
> I encountered a problem about mpirun and SSH when using Open MPI 1.7rc8.
>
> I have a 4-node cluster. This is the hostfile:
>
> [mpiuser@testnode11 openmpi-1.6.4]$ cat ~/work/hostfile
> testnode11
> testnode12
> testnode13
> testnode14
>
> I had configured SSH, copying ".ssh/id_rsa.pub" on testnode11 to
".ssh/authorized_keys" on all the 4 nodes.
> So that I can login all the 4 nodes from testnode11 without a password.
>
> The following test worked well with Open MPI 1.6.4.
>
> [mpiuser@testnode11 openmpi-1.6.4]$ mpirun -hostfile ~/work/hostfile -np 8
~/src/openmpi-1.6.4/examples/ring_c
> Process 0 sending 10 to 1, tag 201 (8 processes in ring)
> Process 0 sent to 1
> Process 0 decremented value: 9
> Process 0 decremented value: 8
> Process 0 decremented value: 7
> Process 0 decremented value: 6
> Process 0 decremented value: 5
> Process 0 decremented value: 4
> Process 0 decremented value: 3
> Process 0 decremented value: 2
> Process 0 decremented value: 1
> Process 0 decremented value: 0
> Process 0 exiting
> Process 4 exiting
> Process 2 exiting
> Process 3 exiting
> Process 1 exiting
> Process 6 exiting
> Process 7 exiting
> Process 5 exiting
>
> However, when I switched to Open MPI 1.7rc8, the same test did not work.
>
> [mpiuser@testnode11 openmpi-1.7rc8]$ mpirun -hostfile ~/work/hostfile -np 8
~/src/openmpi-1.7rc8/examples/ring_c
> Permission denied, please try again.
> Permission denied, please try again.
> Permission denied (publickey,gssapi-keyex,gssapi-with-mic,password).
> [testnode12:06990] [[50636,0],1] ORTE_ERROR_LOG: A message is attempting to
> be
sent to a process whose contact information is unknown in file rml_oob_send.c
at
line 362
> [testnode12:06990] [[50636,0],1] attempted to send to [[50636,0],3]: tag 15
> [testnode12:06990] [[50636,0],1] ORTE_ERROR_LOG: A message is attempting to
> be
sent to a process whose contact information is unknown in file
base/grpcomm_base_xcast.c at line 166
>
> I had checked the logs of SSH, and found the direct reason. A SSH request
> from
testnode12 to testnode14 was denied.
>
> [mpiuser@testnode11 openmpi-1.7rc8]$ ssh root@testnode14 tail -f
/var/log/secure
> ...
> Mar 14 15:39:01 testnode14 sshd[31610]: Connection closed by testnode12
> Mar 14 15:39:04 testnode14 sshd[31611]: Failed password for mpiuser from
testnode12 port 55964 ssh2
> Mar 14 15:39:04 testnode14 sshd[31611]: Failed password for mpiuser from
testnode12 port 55964 ssh2
> Mar 14 15:39:04 testnode14 sshd[31612]: Connection closed by testnode12
> ...
>
> So I am puzzled. I launched mpirun on testnode11, but I do not know why
testnode12 would send a SSH request to testnode14.
> One solution is to copy ".ssh/id_rsa.pub" on all the nodes to
".ssh/authorized_keys"
If all nodes have their own private key without a passphrase set this would
work. OTOH copying the private key of testnode11 to all other nodes should also
do.
> on all the nodes, but that is not what I want.
> Is there any way to control that all the SSH requests are sent from the node
where mpirun executed, to all the nodes?
> I had checked all the orte parameters, and no answer found. Please give some
suggestions.
Depending on the amount of nodes and in case you don't like passphrase-less
ssh-keys at all like I do: setting up hostbased authentication could help:
http://arc.liv.ac.uk/SGE/howto/hostbased-ssh.html
-- Reuti
> Thanks!
> _______________________________________________
> users mailing list
> us...@open-mpi.org
> http://www.open-mpi.org/mailman/listinfo.cgi/users
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