There are many more or less elaborate ways of doing this, but these three simple rules add good basic protection. This will allow a couple of failed SSH login attempts and then add a 60 second cool down. Effectively killing any interest in brute forcing the server in question.To add these rules run the following as root  iptables -A INPUT -p tcp --dport 22 -m state --state NEW -m recent --set --name SSH -j ACCEPT iptables -A INPUT -p tcp --dport 22 -m recent --update --seconds 60 --hitcount 4 --rttl --name SSH -j LOG --log-prefix "SSH_brute_force " iptables -A INPUT -p tcp --dport 22 -m recent --update --seconds 60 --hitcount 4 --rttl --name SSH -j DROP Rules created with the iptables command are stored in memory. If the system is restarted before saving the iptables rule set, all rules are lost. For netfilter rules to persist through a system reboot, they need to be saved. To save netfilter rules, type the following command as root  iptables-save > /etc/sysconfig/iptables = Disable root ssh access =