| Port | Service | Description |
| 20 | FTP (File Transfer Protocol) | Data transfer |
| 21 | FTP (File Transfer Protocol): | Control (command) |
| 22 | SSH (Secure Shell): | Used for secure remote administration and file transfers. |
| 23 | Telnet | Used for remote terminal access. |
| 25 | SMTP (Simple Mail Transfer Protocol): | Used for sending email. |
| 53 | DNS (Domain Name System): | Resolves domain names to IP addresses. |
| 69 | TFTP (Trivial File Transfer Protocol): | Used for simple file transfers. |
| 80 | HTTP (Hypertext Transfer Protocol): | Used for unsecured web traffic. |
| 443 | HTTPS (Hypertext Transfer Protocol Secure) | Used for secure web traffic with encryption. |
| 67 | DHCP (Dynamic Host Configuration Protocol) | Server |
| 68 | DHCP (Dynamic Host Configuration Protocol) | Client |
| 110 | POP3 (Post Office Protocol version 3): | Used for retrieving emails. |
| 143 | IMAP (Internet Message Access Protocol) | Used for accessing and retrieving emails |
| 161 | SNMP (Simple Network Management Protocol): | SNMP |
| 162 | SNMP (Simple Network Management Protocol): | SNMP traps |
| 389 | LDAP (Lightweight Directory Access Protocol) | Used for accessing and maintaining distributed directory information services. |
| 443 | LDAPS (LDAP over TLS/SSL) | Encrypted version of LDAP |
| 465 | SMTPS (SMTP over TLS/SSL) | Encrypted version of SMTP |
| 514 | Syslog | Used for system logging and monitoring. |
| 873 | rsync | Used for file synchronization. |
| 3389 | RDP (Remote Desktop Protocol) | Used for remote desktop connections. |
| 5432 | PostgreSQL | Default port for the PostgreSQL database system. |
| 3306 | MySQL | Default port for the MySQL database system. |
119
| NNTP (Network News Transfer Protocol)
| Used for retrieving Usenet articles.
|
161
| SNMP (Simple Network Management Protocol)
| SNMP
|
162
| SNMP (Simple Network Management Protocol)
| SNMP traps
|