How to block a port in csf

Note: Way to the Web Ltd. (the company behind ConfigServer) has closed permanently on August 31, 2025. However, cPanel now provides a fork of CSF.
cPanel will provide its own fork of CSF starting Feb 25th, 2026

Introduction

This article provides the steps needed to block a port with CSF in WHM.

Note: CSF isn't provided or installed by cPanel. CSF is developed and supported by ConfigServer.

Procedure

1. Log into WHM as the 'root' user.
2. Navigate to Home / Plugins / ConfigServer Security & Firewall.
3. In the csf -ConfigServer Firewall section, click the Firewall Configuration button.
4. Scroll down to Allow incoming TCP ports.
5. Remove the incoming TCP port in the TCP_OUT textbox.
6. Scroll down to Allow outgoing TCP ports.
7. Remove the outgoing TCP port in the TCP_OUT" textbox.
8. Scroll down to Allow incoming UDP ports.
9. Remove the incoming UDP port in the UDP_IN" textbox.
10. Scroll down to Allow outgoing UDP ports.
11. Remove the outgoing UDP port in the UDP_OUT textbox.
12. Scroll to the bottom of the page and click the Change button.
13. Click the Firewall Restart button.