atom feed6 messages in net.sourceforge.lists.courier-usersRe: [courier-users] Re: Esmtp ddos vu...
FromSent OnAttachments
Stephen S. KelleyJan 3, 2003 8:41 am 
Sam VarshavchikJan 3, 2003 2:56 pm 
Stephen S. KelleyJan 3, 2003 5:13 pm 
Sam VarshavchikJan 3, 2003 7:57 pm 
William Dell WisnerJan 4, 2003 12:58 am 
Sam VarshavchikJan 4, 2003 8:34 am 
Subject:Re: [courier-users] Re: Esmtp ddos vulnerability in 0.40.0.20021026?
From:William Dell Wisner (will@dell.wisner.name)
Date:Jan 4, 2003 12:58:42 am
List:net.sourceforge.lists.courier-users

There's no reason to accept more than four concurrent ESMTP connections from the same IP address. Reduce MAXPERC to 10, and MAXPERIP to 4.

Oh, yes there is. It's called NAT.

The problem is particularly acute if you've got people reading their mail using Mozilla, as it seems to like to open multiple concurrent connections to the IMAP server. Two people behind the same NAT gateway reading their mail with Mozilla at the same time can quite easily exhaust a four connection limit.

w.