To prevent dictionary attacks on ssh Several vulnerabilities worms attacking SSH server using dictionaries. This should not be a problem if we have a good password policy, otherwise, there are other ways to secure our SSH service. The most obvious way to prevent access to the host, allowing connections from a small group of IP addresses using a firewall. If you currently are running a firewall you can add the following: Accept incoming SSH connections from trusted addresses. Discard all other connections. Firewall using iptables commands as follows: All connections from the address 192.168.1.200 to port 22 (SSH) deathbian: ~ # iptables-A INPUT-p tcp-m state - state NEW - source 192.168.1.200 - dport 22-j ACCEPT Deny SSH connections to other deathbian: ~ # iptables-A INPUT-p tcp ... Read full article »