ShellTer is an iptables-based firewall. What sets it apart from the rest is that it has built-in SSH brute force protection. It is easy to configure and has an interactive CLI installer.
You can download it from the following link: https://packetstormsecurity.com/files/download/43687/shellter-0.9.5.tar.gz
Source: https://packetstormsecurity.com/files/43687/shellter-0.9.5.tar.gz.html