| Port # | TCP / UDP | Keyword | Protocol Abbreviation | Application or Protocol Name / Comments |
| 7 | TCP + UDP | echo | — | Echo Protocol |
| 9 | TCP + UDP | discard | — | Discard Protocol |
| 11 | TCP + UDP | systat | — | Active Users Protocol |
| 13 | TCP + UDP | daytime | — | Daytime Protocol |
| 17 | TCP + UDP | qotd | QOTD | Quote Of The Day Protocol |
| 19 | TCP + UDP | chargen | — | Character Generator Protocol |
| 20 | TCP | ftp-data | FTP (data) | File Transfer Protocol (default data port) |
| 21 | TCP | ftp | FTP (control) | File Transfer Protocol (control / commands) |
| 23 | TCP | telnet | — | Telnet Protocol |
| 25 | TCP | smtp | SMTP | Simple Mail Transfer Protocol |
| 37 | TCP + UDP | time | — | Time Protocol |
| 43 | TCP | nicname | — | Whois Protocol (also called “Nicname”) |
| 53 | TCP + UDP | domain | DNS | Domain Name Server (Domain Name System) |
| 67 | UDP | bootps | BOOTP / DHCP | Bootstrap Protocol / Dynamic Host Configuration Protocol (Server) |
| 68 | UDP | bootpc | BOOTP / DHCP | Bootstrap Protocol / Dynamic Host Configuration Protocol (Client) |
| 69 | UDP | tftp | TFTP | Trivial File Transfer Protocol |
| 70 | TCP | gopher | — | Gopher Protocol |
| 79 | TCP | finger | — | Finger User Information Protocol |
| 80 | TCP | http | HTTP | Hypertext Transfer Protocol (World Wide Web) |
| 110 | TCP | pop3 | POP | Post Office Protocol (version 3) |
| 119 | TCP | nntp | NNTP | Network News Transfer Protocol |
| 123 | UDP | ntp | NTP | Network Time Protocol |
| 137 | TCP + UDP | netbios-ns | — | NetBIOS (Name Service) |
| 138 | UDP | netbios-dgm | — | NetBIOS (Datagram Service) |
| 139 | TCP | netbios-ssn | — | NetBIOS (Session Service) |
| 143 | TCP | imap | IMAP | Internet Message Access Protocol |
| 161 | UDP | snmp | SNMP | Simple Network Management Protocol |
| 162 | UDP | snmptrap | SNMP | Simple Network Management Protocol (Trap) |
| 179 | TCP | bgp | BGP | Border Gateway Protocol |
| 194 | TCP | irc | IRC | Internet Relay Chat |
| 443 | TCP | https | HTTP over SSL | Hypertext Transfer Protocol over Secure Sockets Layer |
| 500 | UDP | isakmp | IKE | IPSec Internet Key Exchange |
| 520 | UDP | router | RIP | Routing Information Protocol (RIP-1 and RIP-2) |
| 521 | UDP | ripng | RIPng | Routing Information Protocol - “Next Generation” |