More helpful info for cpanel admins.

Summary:
This article lists all the well known, and registered ports that are being used by cPanel. You should consider this ports list if you’re installing 3rd party firewall software.

More information:
The list is divided into two categories: Inbound tcp/udp and Outbound tcp/udp.

Quote:
Inbound ports

TCP
20 – FTP
21 – FTP
22 – SSH
25 – SMTP
26 – SMTP
53 – DNS
80 – HTTP
110 – POP3
143 – IMAP4
443 – HTTPS
465 – SMTP (TLS/SSL)
993 – IMAP4 (SSL)
995 – POP3 (SSL)
2082 – CPANEL
2083 – CPANEL (SSL)
2086 – WHM (Web Host Manager)
2087 – WHM (SSL)
2095 – WEBMAIL
2096 – WEBMAIL (SSL)
3306 – MYSQL (ONLY IF YOU WANT TO ALLOW INCOMING MYSQL CONNECTIONS)
6666 - CHAT

UDP
21 – FTP
53 – DNS
465 – SMTP (TLS/SSL)

Quote:
Outbound ports

TCP
20 – FTP
21 – FTP
25 – SMTP
26 – SMTP
37 – RDATE
43 – WHOIS
53 – DNS
80 – HTTP
113 – IDNET
465 – SMTP (TLS/SSL)
873 – RSYNC
2089 – CPANEL LICENSE
3306 – MYSQL (ONLY IF YOU NEED TO CONNECT TO REMOTE MYSQL SERVER)

UDP
21 – FTP
53 – DNS
465 – SMTP (TLS/SSL)
873 – RSYNC
Note: For more information on standard port assignment, visit the following URL: http://www.iana.org/assignments/port-numbers.