Puertos necesarios para cPanel

Port Service Protocol Direction Notes
20 ftp-data tcp inbound/outbound
21 ftp tcp,udp inbound/outbound
22 ssh tcp inbound
25 smtp tcp inbound/outbound
26 smtp tcp inbound/outbound
37 rdate tcp outbound
43 whois tcp outbound
53 DNS tcp/udp inbound/outbound Inbound only needed if you run your own DNS server
80 http tcp inbound/outbound
110 pop3 tcp inbound
113 ident tcp outbound
143 imap4 tcp inbound
443 https tcp inbound
465 smtp tcp/ssl, tcp/udp inbound/outbound
873 rsync tpc/udp outbound
993 imap4 ssl tcp inbound
995 pop3 ssl tcp inbound
2082 cpanel tcp inbound
2083 cpanel ssl tcp inbound
2086 whm tcp inbound
2087 whm ssl tcp inbound
2089 cp license tcp outbound
2095 webmail tcp inbound
2096 webmail ssl tcp inbound
3306 mysql tcp inbound Only if you need to connect remotely
6666 chat tcp inbound
Fuente: http://knowledgelayer.softlayer.com/faqs/242#333

Fuente mía: Si utilizais dns only de cpanel el puerto 53 lo chapais en el servidor que no haga de dns para evitar ataques dos.

 

Buen aporte Ferrán, gracias por compartir el articulo