[Dovecot] limiting number of incorrect logins per connection

alex@ahhyes.net alex at ahhyes.net
Sat Aug 27 05:18:50 EEST 2011

Thanks for that. I will change it and recompile. Sorry for the grumpyness yesterday in my posts. Was having a bad day. Is there any chance of there being an option on future versions that allow a number of failed auth attempts to be specified before dropping the connection? The other thread you mentioned, I see someone devised a small patch in c to add this functionality. It didnt look like a lot of code to do it. What are your thoughts?

----- Reply message -----
From: "Timo Sirainen" <tss at iki.fi>
Date: Sat, Aug 27, 2011 02:30
Subject: [Dovecot] limiting number of incorrect logins per connection
To: "Alex" <alex at ahhyes.net>
Cc: <dovecot at dovecot.org>

login-common/client-common.h :


So set it to (45*60*1000)

But I don't think there's much of a practical difference between these.

On 26.8.2011, at 12.07, Alex wrote:

> 3 minutes! I think that's too long, how can I drop that down to about 45 seconds?
> On Fri, 26 Aug 2011 11:44:45 +0300, Timo Sirainen wrote:
>> On 26.8.2011, at 10.25, Alex wrote:
>>> Running Dovecot 2 on my server. It is regularly getting dictionary auth attacked. What I have noticed is that once connected to a pop3/imap login session, you can send endless incorrect usernames+passwords attempts. This is a problem for me... I use fail2ban to try and stop these script kiddies. The problem is that fail2ban detects the bad auths, firewalls the IP, however, since it's an "established" session, the attacker can keep authing away... It's only on a subsequent (new) connection that the firewalling will take effect.
>> Umm. If client hasn't managed to log in in 3 minutes, it's
>> disconnected (no matter what it does with the connection).

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