fail2ban or similar?

i've been using, with good results, a script called fail2ban (http://www.fail2ban.org/) on my linux servers. it limits dictionary attacks on incoming SSH and other ports by monitoring failed password attempts. a certain number in a limited time triggers iptables to ban that IP. as i said, it works like a charm on my linux web server and my home machine (which i log into from afar via SSH). now i'd like to see if there's something similar, or a port of fail2ban, for OS X (client and/or server). the main problem i'm having with my 10.4 mail server right now is that occasionally a dictionary attack on POP will clog the pipes and bring the POP server to a halt. luckily, IMAP and SMTP still work during this, but clients who log in using POP are unable to get in until i can log in and restart the POP process. i'd love to find a working fail2ban configuration for OS X/darwin or a similar solution that i can use to ban IPs based on # of connections per minute, failed logins, or something of that nature. i'm using courier (authlib/pop3/imap) to serve mail on this box, by the way.