Hi all,
Help! I'm hoping some of you may be able to at least
lead us in the right direction.
We have been having problems with sending mail from
our mail hub (a Tru64 4.0F box). Some messages leave
campus just fine, while others time out and hang in
the queue. The messages that hang seem to be with
certain ISPs, like Hotmail, Yahoo, Compuserve, as well
as other universities. The messages then return to
sender with a time-out error, and the warning that the
message will keep trying to re-send for five days. We
opened a call with Compaq, and got some knowledgeable
folks on the line, who helped us check all kinds of
things, including our DNS. Our DNS *seems* to be
working fine; we can ping, we can do forward and
reverse lookups. However, when attempting to send some
of these suspect messages, it looks as if DNS is
hanging. BTW, if we shut down our primary DNS server,
we still have this problem, and our secondary DNS
servers are at our ISP.
All of this complicated by the fact that we have been
having network problems caused by a denial-of-service
attack. Our network is back up and running, mail is
coming in, but still we have a number of messages not
being sent. (I'm just crossing my fingers that this
one even goes out!) NOTE: It didn't, hence my sending
from this yahoo account ... please reply to
lemma_at_lvc.edu, thanks!)
I have one other oddity I noticed on this box: when
doing a netstat -a, about 20 occurrences of tcp
requests to port 6000 appear. We have no port 6000 in
our inetd.conf file, and the only thing I could find
about what might access port 6000 is a CDE login. We
ONLY have one CDE login for this machine. Could this
be an attack? Could this cause the mail problems? Does
this even *sound* like a sendmail problem, a DNS
problem, or a network problem? We have been attacking
this from all of these angles, with minimal success,
for the better part of a week.
A little bit of background: we are experiencing the
same problems on other servers within our network
(which makes the network look suspicious, though
is it our mailserver now causing our network
problems?) and we are running Sendmail 8.8.8.
(Upgrading to 8.9.1 is not an option; we need to have
support from Compaq because we don't have a dedicated
system administrator
... there are three of us who share those duties. :)
Any and all help is welcomed!
Thanks,
Sheryl
S H E R Y L A L E M M A
Assistant Director, Administrative Computing
Lebanon Valley College
mailto: lemma_at_lvc.edu
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Received on Fri Jan 28 2000 - 16:32:33 NZDT