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Revision as of 12:30, 5 January 2009 by Janfrode (Talk | contribs)

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If you want to catch this:
Aug 29 19:45:13 MyHostName dovecot-auth: pam_unix(dovecot:auth): authentication failure; logname= uid=0 euid=0 tty=dovecot ruser= rhost=

Here is the regex:
dovecot.*authentication failure.*rhost\=<host>

To catch lines like:
dovecot: pop3-login: Aborted login (1 authentication attempts): user=<usrnm>, method=PLAIN, rip=, lip=
the regexp is:
dovecot.*pop3-login.*Aborted login.*rip=<HOST>.*

CentOS 5.2 and Dovecot:

Create file /etc/fail2ban/filter.d/dovecot.conf
failregex = pam.*dovecot.*(?:authentication failure).*rhost=(?:::f{4,6}:)?(?P<host>\S*)

Add to file /etc/fail2ban/filter.d/jail.conf
enabled = true
filter = dovecot
action = iptables-multiport[name=Dovecot, port="110,995,143,993", protocol=tcp]
logpath = /var/log/secure
maxretry = 3

You can test your config while editing the filter file (in CentOS 5.2):

/usr/bin/fail2ban-regex /var/log/secure /etc/fail2ban/filter.d/dovecot.conf

Don't depend on old breech attempts...create and test fresh ones yourself with jail.conf 'bantime' set to 60 seconds:
bantime = 60

Suggested regexp to catch failed sql-logins:

failregex = dovecot.*auth-worker\(default\): sql\(.*,<HOST>\): Password mismatch