openssh unix dev - Jul 2013 - Any way to over-ride the "-q" option to debug a possible race condition?

I have a slightly complicated question. I am using an mpi application
(Intel impi) which uses ssh to launch applications. For about 0.1-0.2%
of the ssh connections I end up with a zombie, i.e. ps will show [ssh]
<defunct>. Something is going wrong with the ssh when it starts,
perhaps a race condition, it is not disconnecting after some time,
that I have been able to verify.

The most obvious thing I can think of to do is include LogLevel DEBUG
in my .ssh/config to try and trace what is going on, but the ssh
process is being launched with a "-q" embedded in it which is
over-riding this. I am hopeful that there is something I can set to
short-circuit the "-q", although I realise that the chance of their
being some undocumented option is small (but finite).

For reference
 ssh -V
OpenSSH_5.3p1, OpenSSL 1.0.0-fips 29 Mar 2010
impi 4.1

The structure is that mpirun starts mpiexec.hydra which is turn
launches a series of mpi tasks via a ssh connection.

N.B., if there are some known issues with that ssh version that may be
relevant, information would be useful as I could push on the
sys_admin.

-- 
Professor Laurence Marks
Department of Materials Science and Engineering
Northwestern University
www.numis.northwestern.edu 1-847-491-3996
"Research is to see what everybody else has seen, and to think what
nobody else has thought"
Albert Szent-Gyorgi

Laurence Marks ecrivait :
> [...]
> 
> The most obvious thing I can think of to do is include LogLevel DEBUG
> in my .ssh/config to try and trace what is going on, but the ssh
> process is being launched with a "-q" embedded in it which is
> over-riding this. I am hopeful that there is something I can set to
> short-circuit the "-q", although I realise that the chance of
their
> being some undocumented option is small (but finite).
>  [....]
If you cannot change the command line that calls ssh with "-q", a
warkaround can be to change the ssh binary itself to a wrapper that
calls ssh without the "-q".
Just move the binary to ssh.bin, and have a small shell script named
ssh that removes the "-q" option before "exec"-ing ssh.bin.

Hope this helps,

Flavien.

Thanks, very nice and it even works

#!/bin/bash
a=`echo $@ | sed -e 's/-q//'`
ssh $a


On Thu, Jul 18, 2013 at 9:39 AM, Flavien <flavien-ssh at lebarbe.net>
wrote:
> Laurence Marks ecrivait :
>> [...]
>>
>> The most obvious thing I can think of to do is include LogLevel DEBUG
>> in my .ssh/config to try and trace what is going on, but the ssh
>> process is being launched with a "-q" embedded in it which is
>> over-riding this. I am hopeful that there is something I can set to
>> short-circuit the "-q", although I realise that the chance of
their
>> being some undocumented option is small (but finite).
>>  [....]
>
> If you cannot change the command line that calls ssh with "-q", a
> warkaround can be to change the ssh binary itself to a wrapper that
> calls ssh without the "-q".
> Just move the binary to ssh.bin, and have a small shell script named
> ssh that removes the "-q" option before "exec"-ing
ssh.bin.
>
> Hope this helps,
>
> Flavien.


-- 
Professor Laurence Marks
Department of Materials Science and Engineering
Northwestern University
www.numis.northwestern.edu 1-847-491-3996
"Research is to see what everybody else has seen, and to think what
nobody else has thought"
Albert Szent-Gyorgi