Reference
Common ports
A quick-reference table of well-known network ports. Port numbers and protocol assignments here reflect standard, publicly documented usage (IANA).
| Port | Protocol | Service | Description | Risk note |
|---|---|---|---|---|
| 20 | TCP | FTP (data) | File Transfer Protocol data channel. | — |
| 21 | TCP | FTP (control) | File Transfer Protocol control channel. | Transmits credentials in plaintext; prefer SFTP/FTPS. |
| 22 | TCP | SSH | Secure Shell for encrypted remote administration. | — |
| 23 | TCP | Telnet | Unencrypted remote terminal access. | Plaintext protocol — avoid exposing to the internet. |
| 25 | TCP | SMTP | Simple Mail Transfer Protocol for sending email. | — |
| 53 | TCP/UDP | DNS | Domain Name System resolution. | — |
| 67 | UDP | DHCP (server) | Dynamic Host Configuration Protocol, server side. | — |
| 68 | UDP | DHCP (client) | Dynamic Host Configuration Protocol, client side. | — |
| 80 | TCP | HTTP | Unencrypted web traffic. | Prefer HTTPS (443) for anything handling sensitive data. |
| 110 | TCP | POP3 | Post Office Protocol for retrieving email. | — |
| 123 | UDP | NTP | Network Time Protocol for clock synchronization. | — |
| 143 | TCP | IMAP | Internet Message Access Protocol for retrieving email. | — |
| 389 | TCP/UDP | LDAP | Lightweight Directory Access Protocol for directory services. | — |
| 443 | TCP | HTTPS | Encrypted web traffic using TLS/SSL. | — |
| 445 | TCP | SMB | Windows file and printer sharing. | Frequent ransomware target — avoid exposing to the internet. |
| 587 | TCP | SMTP (submission) | Email submission, typically with authentication. | — |
| 993 | TCP | IMAPS | IMAP encrypted with TLS/SSL. | — |
| 995 | TCP | POP3S | POP3 encrypted with TLS/SSL. | — |
| 3306 | TCP | MySQL | MySQL/MariaDB database default port. | Should almost never be exposed directly to the internet. |
| 3389 | TCP | RDP | Remote Desktop Protocol for remote Windows access. | Common brute-force target — use a VPN or MFA, not direct exposure. |
| 5432 | TCP | PostgreSQL | PostgreSQL database default port. | Should almost never be exposed directly to the internet. |
| 8080 | TCP | HTTP (alternate) | Common alternate port for web servers and proxies. | — |
This is a general-purpose reference, not a scan of any specific network. It does not reflect the open ports on your own devices.