| 21 | FTP - File Transfer Protocol |
| 22 | SSH, SFTP - Secure SHell and SSH based FTP |
| 23 | Telnet - non-secure shell |
| 25 | SMTP (Simple Mail Transfer Protocol) - sending and receiving email messages |
| 53 | DNS (Domain Name System) - mapping from hostname to ip and vice versa |
| 80 | HTTP (HyperText Transfer Protocol) - main protocol of world wide web |
| 110 | POP (Post Office Protocol) - mail retrieval protocol |
| 143 | IMAP (Internet Message Access Protocol) - mail retrieval protocol |
| 443 | HTTPS - secure HTTP |
| 3306 | MySQL database |
| 3389 | RDP - Remote Desktop |
