How to Configure a Firewall with CSF on Debian 9

In this article, we will show you how to install and configure the CSF firewall on a Debian 9 VPS, as well as go through some tips on how to use CSF.

ConfigServer Security & Firewall (CSF) is a free and advanced firewall management tool based on iptables. CSF provides a high level of security on your server and is very straightforward, making it easy to set up and install on all supported Linux distributions. We will use Debian 9 which is among the supported Linux distributions. CSF has many great features such as port scanning, SYN floods and brute force attacks for many services that can help you protect your server. One of the very nice features on CSF is that it provides a built-in web UI for managing the firewall from a web browser. This UI integration is supported by cPanel, DirectAdmin, as well as working independently on your server.

The CSF installation also comes with another service called Login Failure Daemon (LFD). LFD actually is a process that monitors the log files and sends email notifications based on the CSF configuration rules. Let’s begin with the installation.