| 20 | TCP | FTP Data | Used for transferring data in FTP sessions. |
| 21 | TCP | FTP Control | Controls FTP commands and authentication. |
| 22 | TCP | SSH | Secure shell for remote logins and command execution. |
| 23 | TCP | Telnet | Legacy remote login service, not encrypted. |
| 25 | TCP | SMTP | Sends email between servers. |
| 53 | UDP/TCP | DNS | Resolves domain names to IP addresses. |
| 67 | UDP | DHCP Server | Assigns IP addresses to devices. |
| 68 | UDP | DHCP Client | Receives IP addresses from DHCP server. |
| 69 | UDP | TFTP | Simplified file transfer protocol. |
| 80 | TCP | HTTP | Standard web traffic. |
| 110 | TCP | POP3 | Retrieves emails from mail servers. |
| 119 | TCP | NNTP | Used for reading and posting Usenet articles. |
| 123 | UDP | NTP | Time synchronization across devices. |
| 135 | TCP | RPC | Remote Procedure Call for Windows services. |
| 137 | UDP | NetBIOS Name Service | Name resolution in Windows networks. |
| 138 | UDP | NetBIOS Datagram Service | Browser and messaging in NetBIOS. |
| 139 | TCP | NetBIOS Session Service | File and printer sharing in Windows. |
| 143 | TCP | IMAP | Access email on a mail server. |
| 161 | UDP | SNMP | Network management monitoring. |
| 162 | UDP | SNMP Trap | SNMP alert messages. |
| 179 | TCP | BGP | Routing information between autonomous systems. |
| 194 | TCP | IRC | Internet Relay Chat. |
| 443 | TCP | HTTPS | Secure HTTP web traffic. |
| 445 | TCP | SMB | Windows file and printer sharing. |
| 465 | TCP | SMTPS | Secure SMTP for sending email. |
| 514 | UDP | Syslog | System log message transport. |
| 515 | TCP | LPD | Line Printer Daemon. |
| 587 | TCP | SMTP Submission | Used to send email securely. |
| 631 | TCP | IPP | Printing protocol. |
| 636 | TCP | LDAPS | Secure LDAP. |
| 873 | TCP | rsync | File synchronization tool. |
| 993 | TCP | IMAPS | Secure IMAP for email retrieval. |
| 995 | TCP | POP3S | Secure POP3 for email retrieval. |
| 1080 | TCP | SOCKS Proxy | Internet proxy protocol. |
| 1433 | TCP | MSSQL | Microsoft SQL Server. |
| 1521 | TCP | Oracle DB | Oracle database service. |
| 1723 | TCP | PPTP | VPN tunneling protocol. |
| 2049 | TCP/UDP | NFS | Network File System. |
| 3306 | TCP | MySQL | MySQL database service. |
| 3389 | TCP | RDP | Remote Desktop Protocol. |
| 5432 | TCP | PostgreSQL | PostgreSQL database service. |
| 5900 | TCP | VNC | Virtual Network Computing for remote desktop. |
| 6000 | TCP | X11 | X Window System. |
| 8080 | TCP | HTTP-alt | Alternative HTTP port. |
| 8443 | TCP | HTTPS-alt | Alternative HTTPS port. |