Fail2ban scans log files (e.g. /var/log/apache/error_log) and bans IPs that show the malicious signs -- too many password failures, seeking for exploits, etc. Generally Fail2Ban is then used to update firewall rules to reject the IP addresses for a specified amount of time...
SSHGuard monitors services through their logging activity. It reacts to messages about dangerous activity by blocking the source address with the local firewall. SSHGuard employs a clever parser that can transparently recognize several logging formats at once (syslog, syslog-ng...
The idea of denying access to SSH servers is nothing new and I was inspired by many other scripts that I discovered. However, none of them did things the way I envisioned them to. Also, they were all shell scripts which do not offer the elegance of Python.
