Date: Fri, 29 Jun 2007 15:47:25 -0700 From: Steve Kargl <sgk@troutmask.apl.washington.edu> To: David Malone <dwmalone@maths.tcd.ie> Cc: freebsd-current@freebsd.org Subject: Re: SYNCOOKIE authentication problems Message-ID: <20070629224725.GA72396@troutmask.apl.washington.edu> In-Reply-To: <200706292227.aa62881@salmon.maths.tcd.ie> References: <20070629163247.GA6373@troutmask.apl.washington.edu> <200706292227.aa62881@salmon.maths.tcd.ie>
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On Fri, Jun 29, 2007 at 10:27:06PM +0100, David Malone wrote:
> > Jun 29 09:21:58 node11 kernel: TCP: [192.168.0.12]:54528 to [192.168.0.11]:526
>
> OK - I can see the packets corresponding to this error by doing something
> like:
>
> % tcpdump -S -r synfinrstdata -n port 62391 and port 60621
(output elided).
> The start of this looks like a perfectly normal TCP connection -
> it opens normally, transfers about 12 bytes in one direction and
> then closes. Strangley, 192.168.0.11 then sends two FIN packets,
> followed by a reset. The error message produced by the kernel should
> have produced a reset in response, but I'm not sure I can see quite
> enough to see what happened.
>
> We could try to get all of the packets in the connection by doing:
>
> tcpdump -i whatever_interface -w /tmp/fulldump -s 80
I'm doing this now. It seems that putting bge0 in promiscous mode
has provided some stability. fulldump is currently at 2.4 GB.
> > poll({4/POLLIN 5/POLLIN 6/POLLIN 7/POLLIN 9/POLLIN 10/POLLIN 11/POLLIN 13/POLL
>
> It looks like MPI is looking only for file discriptors to become
> ready for reading. I'd guess one of the file discriptors is in an
> error state, but MPI isn't checking for theat, so it is spinning.
>
I've both OpenMPI and MPICH2 implementation. Neither handles a disappearing
process in an elegant manner. They simply assume that network is robust
and 100% reliable.
--
Steve
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