dccm timeout lets spam through

Gary Mills mills@cc.UManitoba.CA
Fri Mar 28 14:38:29 UTC 2003


On Thu, Mar 27, 2003 at 09:39:31AM -0700, Vernon Schryver wrote:
> > From: Gary Mills <mills@cc.UManitoba.CA>
> 
> > We had a couple of incidents today where `dccm' logged timeouts
> > connecting to `dccd', and was unable to reject bulk mail.  There were
> > high volumes of incoming mail each time, so it's likely related to the
> > number of connections or the connection rate.  After each incident,
> > `dccm' seemed to return to normal. Is there something I can adjust in
> > the dccm or dccd configuration to prevent this from happening?
> > ...
> 
> Those log look entries look like dccd not responding.  Was dbclean
> running at the time?  Were there any complaints in the logs from 
> dccd?  Is the system running dccd short of RAM?

`dbclean' ran at 02:45, long before those incidents.  `dccd' didn't
log any errors all day.  There are two servers running, though.  The
other one did log some curious errors:

Mar 26 11:38:43 naos dccd[22130]: short packet of 14 bytes from 130.179.16.23
Mar 26 11:38:43 naos dccd[22130]: "short packet of 14 bytes" sent to client 0 at 130.179.16.23,47676
...
Mar 26 11:39:14 naos dccd[22130]: short packet of 2 bytes from 130.179.16.23
Mar 26 11:39:14 naos dccd[22130]: "short packet of 2 bytes" sent to client 0 at 130.179.16.23,47676

At the same time, `dccm' logged these errors:

Mar 26 11:38:05 electra dccm[922]: [ID 247806 mail.error] 1 too many simultaneous mail messages
Mar 26 11:38:06 electra dccm[922]: [ID 247806 mail.error] 2 too many simultaneous mail messages
...
Mar 26 11:40:13 electra dccm[922]: [ID 247806 mail.error] 3 too many simultaneous mail messages
Mar 26 11:40:44 electra dccm[922]: [ID 702911 mail.error] no answer from naos.cc.umanitoba.ca (130.179.16.122,6277) after 3778 ms
Mar 26 11:40:44 electra dccm[922]: [ID 702911 mail.error] skip asking DCC 1.000 seconds more after failure
...
Mar 26 17:06:39 electra dccm[922]: [ID 702911 mail.error] skip asking DCC 128.000 seconds more after failure
Mar 26 17:06:40 electra dccm[922]: [ID 702911 mail.error] skip asking DCC 128.000 seconds more after failure

I restarted both `dccd' and `dccm' on electra that evening.

-- 
-Gary Mills-    -Unix Support-    -U of M Academic Computing and Networking-



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