Most Linux servers offer an SSH login via Port 22 for remote administration purposes. This port is a well-known port, therefore, it is often attacked by brute force attacks. Fail2ban is a software that scans log files for brute force login attempts in real-time and bans the attackers with firewalld or iptables. This tutorial shows the installation and configuration of Fail2Ban with firewalld on CentOS 7.
Read the original at Howtoforge Linux Howtos und Tutorials.