Weird SMTP timeouts

John Abreau jabr at blu.org
Tue Jun 13 17:52:02 EDT 2006


Tom Metro wrote:

> You mean you want to see the full contents of what is being sent through
> the socket? Dig deeper into the tcpdump man page. I believe there is an
> option to dump the packet contents. Or use a GUI sniffer as others
> suggested.

I believe tcpdump is telling me helmsbriscoe never responds at all
when sendmail tries to connect. But I'm not familiar enough with
tcpdump to be sure I'm using it correctly.

Also, I only see that when I filter only on the port:

    tcpdump -vv port 25

I've also tried

    tcpdump -vv host smtp.helmsbriscoe.com
    tcpdump -vv host host hbmail01.helmsbriscoe.com
    tcpdump -vv host 64.16.17.140
    tcpdump -vv net 64.16.17

and got nothing at all, not even the single helmsbriscoe line that
I get  when filtering on port 25.

My mail server doesn't have X11 on it; even with ssh -Y, I'm unable
to run ethereal.


>> When I ran the sendmail queue, the four messages each showed just a
>> single match, sending to helmsbriscoe and never receiving a response...
> 
> This may be misleading due to ESMTP pipelining. Multiple commands may be
> bundled into one packet. Though I'd still expect there to be a few
> packets sent back and forth for the initial handshake used to determine
> if the server supports ESMTP pipelining.
> 
>  -Tom
> 

Can that pipelining be turned off during the queue run?


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