Sshguard monitors ssh servers from their logging activity. It reacts to messages
about dangerous activity by blocking the source address with the local firewall.

Sshguard can operate all the major firewalling systems:
* PF (OpenBSD, FreeBSD, NetBSD, DragonFly BSD)
* netfilter/iptables (Linux)
* IPFIREWALL/ipfw (FreeBSD, Mac OS X)

Sshguard is reliable, easy to set up and demands very few resources to the
system.

WWW: http://sshguard.sourceforge.net