Good advice!
I will upgrade the Dovecot as it sounds like a good idea. I was also
considering just redirecting the inbound port from 110 to another port.
Your simple answer is much appreciated.
Thanks for helping without the "corrective elitist attitude"!
-----Original Message-----
From: centos-bounces@xxxxxxxxxx [mailto:centos-bounces@xxxxxxxxxx] On Behalf
Of Scott Silva
Sent: Thursday, November 20, 2008 4:03 PM
To: centos@xxxxxxxxxx
Subject: Re: SYD flood dropped on Sendmail (centos 4.x)
on 11-20-2008 3:31 PM Kai Schaetzl spake the following:
> Chris Heiner wrote on Thu, 20 Nov 2008 13:43:44 -0800:
>
>> I get complaints about "the servers asking for username and password".
>
> from your users or what? Of course, they may complain. A big dictionary
> attack can take almost all the bandwidth for some time or leave a backlog
> of dovecot instances.
> Please, as I understand you are a server adminstrator for quite a few
> machines, correct? Yet, you are answering in a way as if you just brought
> your first server online.
>
> Btw, it's a *SYN* flood, not a SYD flood and that won't change even if you
> repeat it again and again.
>
> I
>> started test@ accounts all many servers to try and track it down.
>
> Pardon, you did what?
>
>> I have tried restarting POP and SMTP in the past
>
> You may want to kill all dovecot instances, in case you *are* running
> dovecot (if not, then of what you use, but I know that dovecot likes to
> hang in this way if hammered). Just restarting it may not kill the backlog
> of hanging connections. A "ps ax|grep login" would help to see if
> instances are still running.
> Restarting SMTP: again, this has nothing to do with SMTP!
>
> Kai
>
CentOS 4 comes with a very OLD version of dovecot.
If you are using dovecot, you can get a much newer version at atrpms.net.
The upgrade might be all you need to fix it.
--
MailScanner is like deodorant...
You hope everybody uses it, and
you notice quickly if they don't!!!!
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