[CentOS-es] Ataque Diccionario en Dovecot

[Luis Alberto Roman Aguirre]

Buenas listeros:
Les comento, tengo un servidor de correos en postfix con autenticacion en dovecot,  pero en ciertos dias el servidor sufre de ataques de diccionario  (  o  al  menos eso  creo),  le instale el  fail2ban  para que bannee a las IP  que tratan de conectarse pero aun asi sigo teniendo  problemas. Ahi va la salida de logwatch : pastebin (http://pastebin.com/L3sb7trF# 
dovecot:    Authentication Failures:
       sales rhost=222.218.142.194 : 20 Time(s)
       paul rhost=222.218.142.194 : 18 Time(s)
       admin rhost=222.218.142.194 : 16 Time(s)
       daniel rhost=222.218.142.194 : 16 Time(s)
       peter rhost=222.218.142.194 : 14 Time(s)
       john rhost=222.218.142.194 : 12 Time(s)
       office rhost=222.218.142.194 : 12 Time(s)
       temp rhost=222.218.142.194 : 12 Time(s)
       test rhost=222.218.142.194 : 12 Time(s)
       anna rhost=222.218.142.194 : 10 Time(s)
       cyrus rhost=222.218.142.194 : 10 Time(s)
       help rhost=222.218.142.194 : 10 Time(s)
       news rhost=222.218.142.194 : 10 Time(s)
       thomas rhost=222.218.142.194 : 10 Time(s)
       veronica rhost=222.218.142.194 : 10 Time(s)
       vladimir rhost=222.218.142.194 : 10 Time(s)
       webadmin rhost=222.218.142.194 : 10 Time(s)
       webmaster rhost=222.218.142.194 : 10 Time(s)
       amanda rhost=222.218.142.194 : 8 Time(s)
       backup rhost=222.218.142.194 : 8 Time(s)
       caroline rhost=222.218.142.194 : 8 Time(s)
       contact rhost=222.218.142.194 : 8 Time(s)
       demo rhost=222.218.142.194 : 8 Time(s)
       donald rhost=222.218.142.194 : 8 Time(s)
       edward rhost=222.218.142.194 : 8 Time(s)
       evita rhost=222.218.142.194 : 8 Time(s)
       jeff rhost=222.218.142.194 : 8 Time(s)
       marketing rhost=222.218.142.194 : 8 Time(s)
       martin rhost=222.218.142.194 : 8 Time(s)
       merlin rhost=222.218.142.194 : 8 Time(s)
       michael rhost=222.218.142.194 : 8 Time(s)
       michel rhost=222.218.142.194 : 8 Time(s)
       mike rhost=222.218.142.194 : 8 Time(s)
       oracle rhost=222.218.142.194 : 8 Time(s)
       postfix: 8 Time(s)
       postmaster rhost=222.218.142.194 : 8 Time(s)
       staff rhost=222.218.142.194 : 8 Time(s)
       student rhost=222.218.142.194 : 8 Time(s)
       thierry rhost=222.218.142.194 : 8 Time(s)
       albert rhost=222.218.142.194 : 6 Time(s)
       bdsistemas: 6 Time(s)
       info rhost=222.218.142.194 : 6 Time(s)
       james rhost=222.218.142.194 : 6 Time(s)
       tom rhost=222.218.142.194 : 6 Time(s)
       abc rhost=222.218.142.194 : 4 Time(s)
       admins rhost=222.218.142.194 : 4 Time(s)
       alex rhost=222.218.142.194 : 4 Time(s)
       dan rhost=222.218.142.194 : 4 Time(s)
       elena rhost=222.218.142.194 : 4 Time(s)
Gracias  por la ayuda estimados.
Luis Roman