Howtoforge published a tutorial about how to install CSF Firewall on Debian 11.
How to Install CSF Firewall on Debian 11
ConfigServer Firewall (CSF) is a Firewall for Linux servers and BSD systems to control the inbound and outbound traffic. Before we go into specific details about CSF, let's understand what a firewall is and how it works.
A firewall acts as a shield that protects the system from an outside attack. A few of them are stateful firewalls, circuit-level gateways, UDP/ICMP-filtering firewalls, or application-layer filters.
