Background:
After getting complaints about mails which could not be delieverd to us
i checked the logfiles and found nothing. By nothing i really mean
nothing. Postfix did not even log a "connect from".
So i started to snoop on the network and found out that incoming mails
from one of their server does (SYN), we (SYN, ACK) they (ACK) and then
Postfix sends his "220 smtp..." stuff. But when mails are coming from
another server they (SYN), we (SYN, ACK), they (ACK) and then we again
(SYN, ACK) (which after a few more (TCP Dup ACK) and (SYN, ACK) leads to
a [RST, ACK]).
As our server team has recently patched the solaris machine postfix is
running on, this behaviour could be a bug releated to this patching.
So my idea was to temporarely change the solaris postfix machine with my
linux laptop, making sure it uses the same IP and MAC Address and some
basically configured postfix, while using tcpdump to check if these
connections behave like before.
My Question:
While i am snooping and waiting for connections from this particular
server, other incoming mails should be rejected by this temporary
postfix. But only in a "soft" reject manner. So is there a way to
configure (or missconfigure?) postfix to tell every incoming attempt
something like "Sorry, i have a temporary problem. Try to connect later".
Best regards,
Matthias
--
Matthias Egger
IT Support Gruppe D-ITET (ISG.EE)
ETH Zürich, ETL F 24.1
Physikstrasse 3
8092 Zürich
+41 (0)44 632 03 90
