[ILUG] problem with win9x clients talking to linux sendmail.

[Kenn Humborg]

> When this error occurs there is no record of a failure logged to
> /var/log/maillog, ie sendmail doesn't even get the connection. Here's a
> tcpdump of what i /think/ is a session that caused outlook to give the
> above error:

[...snip...]

> As i understand it: 
> 
> The windows machine tries to connect, 
> Linux responds with a SYN + ack.
> The windows machine acks our SYN, no data.
> <30 second pause>
> The windows machine terminates the connection and acks our SYN.
> linux acks the win9x FIN
> <no response from win9x>
> linux acks the FIN again
> Win9x sends a RST.
> 
> This particular client was Win95 4.0.95B.
> 
> So my question: 
> 
> why the 30 second pause? Why doesn't sendmail respond to the connection?
> Has anyone seen this problem before? Is it a linux tcp stack problem? or
> is it sendmail?

Have you tried manually telnetting from that Win9x box to port 25?
Is it a reverse DNS lookup issue?  

Later,
Kenn