Certification by CompTIA
| Port No. | TCP | UDP | Protocol | Description |
|---|---|---|---|---|
| 9 | UDP | Wake-on-LAN | ||
| 20 | TCP | UDP | ftp (File Transfer Protocol) | data transfer |
| 21 | TCP/SCTP | UDP | ftp (File Transfer Protocol) | control command |
| 22 | TCP/SCTP | UDP | ssh (Secure Shell) | ~> scp(Secure Copy Protocol), sftp(SSH File Transfer Protocol) |
| 23 | TCP | UDP | telnet | unencrypted text communications |
| 25 | TCP | UDP | smtp (Simple Mail Transfer Protocol) | email routing between mail servers. SMTP communication between mail servers uses port 25. Mail clients on the other hand, often submit the outgoing emails to a mail server on port 587. Despite being deprecated, mail providers sometimes still permit the use of nonstandard port 465 for this purpose. |
| 37 | TCP | UDP | time protocol | |
| 38 | TCP | UDP | rap (Route Access Protocol) | |
| 39 | TCP | UDP | rlp (Resource Location Protocol) | |
| 42 | TCP | UDP | Host Name Server Protocol | |
| 53 | TCP | UDP | DNS (Domain Name System) | |
| 67,68 | TCP | UDP | DHCP (Dynamic Host Configuration Protocol) | |
| 69 | TCP | UDP | tftp (Trivial File Transfer Protocol) | |
| 80 | TCP/SCTP | UDP | http (Hypertext Transfer Protocol) | |
| 88 | TCP | UDP | Kerberos authentication system | |
| 101 | TCP | UDP | NIC host name | |
| 109 | TCP | UDP | pop2 (Post Office Protocol, version 2) | |
| 110 | TCP | UDP | pop3 (Post Office Protocol, version 3) | |
| 143 | TCP | UDP | imap (Internet Message Access Protocol) | management of electronic mail messages on a server |
| 220 | TCP | UDP | imap3 (Internet Message Access Protocol, version 3) | management of electronic mail messages on a server |
| 389 | TCP | UDP | ldap (Lightweight Directory Access Protocol) | |
| 443 | TCP | UDP | https (Hypertext Transfer Protocol over TLS/SSL) | |
| 445 | TCP | smb (Microsoft-DS SMB file sharing) | ||
| 464 | TCP | UDP | Kerberos Change/Set password | |
| 465 | TCP | UDP | smtps (Authenticated SMTP over TLS/SSL) | |
| 520 | UDP | RIP (Routing Information Protocol) | ||
| 546 | TCP | UDP | DHCPv6 client | |
| 547 | TCP | UDP | DHCPv6 server | |
| 548 | TCP | afp (Apple Filing Protocol over TCP) | ||
| 587 | TCP | smtp (Simple Mail Transfer Protocol) | email message submission | |
| 853 | TCP | UDP | DNS over TLS | |
| 989 | TCP | UDP | FTPS Protocol (data), FTP over TLS/SSL | |
| 990 | TCP | UDP | FTPS Protocol (control), FTP over TLS/SSL | |
| 992 | TCP | UDP | Telnet protocol over TLS/SSL | |
| 993 | TCP | imaps (Internet Message Access Protocol over TLS/SSL) |