The following are commonly used port numbers in cpanel, to login to your cpanel. you’ll have to use those ports in the form of http://www.domain.com:2082/

Port 2082 -> Cpanel default port
Port 2083 -> Cpanel over SSL
Port2086 -> Cpanel Webhost Manager (default)
Port 2087 -> Cpanel Webhost Manager (with https)
Port 2095 -> Cpanel Webmail
Port 2096 -> Cpanel secure webmail over SSL

if you are using a firewall make sure you should unblock those ports in TCP. You can also add the following Ports;

Port 80 > Apache HTTP web server
Port 21 > FTP
Port 22 > SSH (you will get lot of ssh attacks if you leave it open. change the port to something else)
Port 25 > SMTP (outgoing email)
Port 110 > POP3 (incoming email)
Port 53 > DNS server (if you run DNS server)