Intelligently block brute-force attacks by aggregating system logs
SSHGuard protects hosts from brute-force attacks against SSH and other services. It aggregates system logs and blocks repeat offenders using several firewall backends, including iptables, ipfw, and pf.
brutesshd is an application written in c/php in order to prevent bruteforce attacks through ssh. Brutesshd uses iptables/pfctl tools to block this type of attacks