cyrus 2.5 imap idle/stuck connections (DOS like)

[Heiler Bemerguy]

Hail,

I've noticed an user with ~200 open connections to cyrus  imap port 
(143) and, because of him, no one else could login to the server.

I've noticed even with a single "telnet ip 143", the connection is 
accepted and never ever dropped, even while still unauthenticated.

How to stop that from happening?

cyrus.conf:
imap            cmd="imapd -U 30" listen="imap" prefork=6 maxchild=200


-- 
Atenciosamente,

Heiler Bensimon Bemerguy - CINBESA
Analista de Redes, Wi-Fi,
Virtualização e Serviços Internet
(55) 91 98151-4894