Using CSF, how can I limit the number of connections to specific ports?

Note: Way to the Web Ltd. (the company behind ConfigServer) has announced it will close permanently on August 31, 2025. As of February 25, 2026, cPanel now provides up to date versions of the ConfigServer Firewall:
cPanel will provide its own fork of CSF starting Feb 25th, 2026

Question

I'd like to limit connections to specific ports in order to protect my server against DOS attacks. Is there a way to do this with CSF Firewall?

Answer

Yes, CSF provides a way to limit concurrent connections to specific ports. As an example, the following may be added to the configuration file to limit port 80 and port 443 to 5 connections.

CONFIG_TEXT: CONNLIMIT = "80;5,443;5"

You can read more about this in the CSF Readme.