Limit ssh brute force attacks

This will limit incoming connections to port 22 to no more than 4 attemps in ten minutes. Any more will be dropped. You can adjust the numbers yourself to limit connections further.

iptables -I INPUT -p tcp --dport 22 -i eth0 -m state --state NEW -m recent   --set
iptables -I INPUT -p tcp --dport 22 -i eth0 -m state --state NEW -m recent   --update --seconds 600 --hitcount 4 -j DROP

(Found here http://blog.blackdown.de/2005/02/18/mitigating-ssh-brute-force-attacks-with-ipt_recent/