Because cPanel installs many different services on your server, you need to open a variety of ports depending on your goals and usage.
With the list of inbound ports from cPanel's documentation, you can use HeatShield to configure the firewall for your cPanel servers.
Specifically, you will want to open the following ports to access the control panel itself:
To use HeatShield to open ports on your cPanel server, you can create a new ruleset that contains only the rules related to cPanel. If you have multiple cPanel servers, you can apply this ruleset to each cPanel server.
First, connect your server to HeatShield and upgrade it to use custom rulesets.
Then, open your Rulesets page and click Create Ruleset.
Next, name your ruleset and click Create Ruleset.
Now, create a new firewall rule by selecting the policy, the destination, and the source.
Set the Policy to Allow and the Source to Any.
Select Custom from the Destination dropdown and enter TCP 20 as the FTP port. Click Add.
Repeat this step for each of the cPanel ports you need to open on your server.
Your final ruleset will look similar to this example but with only the ports open to the services you need to use:
To apply your new ruleset to your cPanel server, open the server in HeatShield.
Select your cPanel ruleset from the drop-down list and click Apply Ruleset.
Your new ruleset will be applied.