Fail2ban is an open source, free tool which is the best out there in helping you protect from brute force attacks or DDOs attacks. It achieves its task by monitoring the service logs for any kind of malicious activity. To scan log files, regular expressions are used by Fail2ban. Fail2ban scans and then if any pattern that matches is counted. When this count reaches a certain threshold which is predefined, it bans the IP of the offending machine. The installation process of Fail2ban is very easy as it is already in the default repositories of debian 11. Let’s explore the steps in installing Fail2ban one by one. Step1: To install Fail2ban, run the following command in the Debian 11 terminal