| 20 | TCP | FTP Data | File Transfer Protocol (data transfer) |
| 21 | TCP | FTP Control | File Transfer Protocol (control) |
| 22 | TCP | SSH | Secure Shell (secure remote login) |
| 23 | TCP | Telnet | Unencrypted remote login protocol |
| 25 | TCP | SMTP | Simple Mail Transfer Protocol (email sending) |
| 53 | TCP/UDP | DNS | Domain Name System |
| 67 | UDP | DHCP Server | Dynamic Host Configuration Protocol (server) |
| 68 | UDP | DHCP Client | Dynamic Host Configuration Protocol (client) |
| 80 | TCP | HTTP | Hypertext Transfer Protocol (web) |
| 110 | TCP | POP3 | Post Office Protocol v3 (email retrieval) |
| 143 | TCP | IMAP | Internet Message Access Protocol (email) |
| 443 | TCP | HTTPS | HTTP over TLS/SSL (secure web) |
| 465 | TCP | SMTPS | SMTP over SSL (secure email sending) |
| 587 | TCP | SMTP Submission | SMTP mail submission (modern) |
| 993 | TCP | IMAPS | IMAP over SSL (secure email) |
| 995 | TCP | POP3S | POP3 over SSL (secure email) |
| 1433 | TCP | MSSQL | Microsoft SQL Server database |
| 1521 | TCP | Oracle DB | Oracle database listener |
| 2049 | TCP/UDP | NFS | Network File System |
| 2375 | TCP | Docker | Docker REST API (plain) |
| 2376 | TCP | Docker TLS | Docker REST API (TLS) |
| 3000 | TCP | Dev Server | Common development server port |
| 3306 | TCP | MySQL | MySQL database server |
| 3389 | TCP | RDP | Remote Desktop Protocol (Windows) |
| 4000 | TCP | Dev Server | Common alternative dev server port |
| 5432 | TCP | PostgreSQL | PostgreSQL database server |
| 5900 | TCP | VNC | Virtual Network Computing (remote desktop) |
| 6379 | TCP | Redis | Redis key-value store |
| 6443 | TCP | Kubernetes API | Kubernetes API server (secure) |
| 8080 | TCP | HTTP Alt | Alternative HTTP port (proxies/dev) |
| 8443 | TCP | HTTPS Alt | Alternative HTTPS port |
| 27017 | TCP | MongoDB | MongoDB database server |
