7 messages in net.sourceforge.lists.courier-usersRe: [courier-users] Need Some Advice ...
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Bill TaroliOct 12, 2006 11:30 am 
Mark BucciarelliOct 12, 2006 11:46 am 
Bill TaroliOct 12, 2006 12:21 pm 
Kenny DailOct 12, 2006 12:48 pm 
Sam VarshavchikOct 12, 2006 3:15 pm 
Bill TaroliOct 12, 2006 4:08 pm 
Bill TaroliOct 14, 2006 6:09 pm 
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Subject:Re: [courier-users] Need Some Advice on SMTP overload issueActions...
From:Kenny Dail (ke@amigo.net)
Date:Oct 12, 2006 12:48:58 pm
List:net.sourceforge.lists.courier-users

Just lately, one of my courier servers has been getting into a bit of a pickle. In particular, we're getting hammered by so many incoming spam connections that we hit the (as configured) 40 process limit on SMTP. Unfortunately, some of these processes seem to hang open, and I'm not really sure why. This is on FC3 and Courier 0.50.0 (authlib 0.57).

The seeming to hang open is likely due to Courier's tarpitting. Courier will delay response to SMTP commands (up to 128 secs) if there are errors (like user unknown). Due to the delay in response, this can lead to creating a DOS type situation real easily especially if the max connections is low. Last I heard there was no way to customize the tarpit behavior to fit your needs without hacking the source.

-- Kenny Dail <ke@amigo.net>