Some owners will enable firewalls or block ports.
The following are used by cPanel and should not be blocked:
| Port | Service | Protocol | Direction |
| 20 | ftp | 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 | whos | tcp | outbound |
| 53 | DNS | tcp/udp | inbound/outbound |
| 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 |
| 6666 | chat | tcp | inbound |