Short listing of all the well known, and registered ports that are being used by cPanel. You should keep this list handy when installing 3rd party applications or securing your box. A more detailed listing of ports is available here (http://www.buffaloit.com/forum/showthread.php?t=588).

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

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)

That is helpful....i don't get to research ports very much....knowing them is pretty helpful.