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On 06/07/12 14:08, Mark Stodola wrote:
> On 07/06/2012 04:06 AM, Anne Wilson wrote: Logwatch on my laptop 
> tells me
> 
> Listed by source hosts: Dropped 30 packets on interface eth0 From 
> 192.168.0.40 - 30 packets to tcp(38575)
> 
> 192.168.0.40 is a mail/file/print server running SL.  It may also 
> be relevant that the laptop has fstab mounts to data areas on the 
> server.
> 
> I feel that there must be some way I can trace what is actually 
> sending those packets, so that I can make an assessment, but I've 
> no idea how/where to look.  I see that it's an unallocated
> address, so I've no pointer at all.
> 
> Where should I start looking?
> 
> Anne
> 
> If the connection is still active, you can use a combination of 
> 'netstat -na' and/or 'lsof -nP -i4' to find the process owning the 
> connection. If it isn't, it will be difficult to track down
> without fancier logging/capturing tools.  You mentioned remote
> mounts, but not what method (CIFS, NFS, etc).  If it is NFS,
> pseudo-random ports are chosen for the client connections and may
> be your culprit.
> 
It is indeed NFS.  The logs show ~6 of these high-number allocated
ports listening, so you could well be right.  Is there any way to
confirm that?  I have several nfs mounts in fstab.  One for each mount
probably explains it.

netstat -na | grep 38575 tells me that it is listening:

on the laptop:
tcp        0      0 0.0.0.0:38575               0.0.0.0:*
      LISTEN

but doesn't give me any clue as to what it hears :-)

On the server, lsof -nP -i4 doesn't show anything that I can identify
as the culprit.  Most of the tcp activity comes from either rpc.statd
and related files of dovecot IMAP.  Mail is checked every 5 minutes
during working hours, so if it is that, I would expect to see more
consistent drops.

What do you think?  Am I making false assumptions?

Anne
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