Fail2ban is a free and open source software we can use to mitigate brute force and DoS/DDoS attacks: it scans log files for multiple failed authentication attempts and bans related IP addresses by creating ad-hoc firewall rules. In this tutorial, we see how to install and configure fail2ban on Linux, and we learn the basic concepts behind its usage.

Source: LXer – How to install and configure Fail2ban on Linux