The following iptables will help limit the bruteforce attacks on your ssh port. With the recent exploit found in BASH, there’s been renewed interest in exploitable CGI/Web and SSH ports.
sudo /sbin/iptables -N LOGDROP
sudo /sbin/iptables -A LOGDROP -j LOG
sudo /sbin/iptables -A LOGDROP -j DROP
sudo iptables -I INPUT -p tcp --dport 22 -i eth0 -m state --state NEW -m recent --set
sudo iptables -I INPUT -p tcp --dport 22 -i eth0 -m state --state NEW -m recent --update --seconds 60 --hitcount 4 -j LOGDROP
As seen on http://www.rackaid.com/blog/how-to-block-ssh-brute-force-attacks/