In computer networking, a port is a communication endpoint. At the software level, within an operating system, a port is a logical construct that identifies a specific process or a type of network service. Ports are identified for each protocol and address combination by 16-bit unsigned numbers, commonly known as the port number. A port is always associated with an IP address of a host and the protocol type of the communication. You must open all of these ports in the server firewall to run the cPanel perfectly.
The following are some of the port numbers commonly used by Cpanel and Web Host Manager for management. You will have to use those ports in the form of http://www.yourdomain.com:2082/
|Cpanel over (SSL)
|WHM over (SSL)
|Cpanel Webmail over (SSL)
|SMTP (outgoing email)
|DNS (if you run DNS server)
|POP3 (incoming email)
|Apache HTTP web server
Cpanel secure webmail over SSL. If you are using a firewall make sure to unblock those ports in TCP. The following additional ports should also be kept open: Port 80 > Apache HTTP web server.
Port 22 > SSH (you will get a lot of ssh attacks if you leave it open. change the port to something else).
If you are having trouble accessing cPanel, emails, FTP, etc, you may be having firewall port forwarding issues as certain ports need to be activated for these services to work.
Most software firewalls will prompt you when you first try and access these ports so you just need to click allow. However, some more advanced software firewalls and most hardware firewalls(usually built into your router/modem) do not offer these prompts prompt. In this case, you need to manually open these ports as per the applications/routers instruction manual.