Web
| Port | Protocol | Service |
|---|---|---|
| 80 | TCP | HTTP |
| 443 | TCP (and UDP for HTTP/3) | HTTPS |
| Port | Service | Note |
|---|---|---|
| 25 | SMTP between mail servers | Often blocked for outgoing mail on cloud networks |
| 587 | SMTP submission (STARTTLS) | What mail apps use to send |
| 465 | SMTP submission (TLS) | Also used by mail apps |
| 993 | IMAP over TLS | Reading mail |
| 995 | POP3 over TLS | Downloading mail |
Remote access and files
| Port | Service |
|---|---|
| 22 | SSH and SFTP |
| 21 | FTP (unencrypted; prefer SFTP) |
| 3389 | Windows Remote Desktop (RDP) |
Control panels
| Port | Service |
|---|---|
| 2083 / 2087 | cPanel / WHM over HTTPS |
| 8443 | Plesk over HTTPS |
Databases and caches
| Port | Service |
|---|---|
| 3306 | MySQL / MariaDB |
| 5432 | PostgreSQL |
| 1433 | Microsoft SQL Server |
| 27017 | MongoDB |
| 6379 | Redis |
Infrastructure
| Port | Service |
|---|---|
| 53 | DNS (UDP and TCP) |
| 123 | NTP time sync (UDP) |
| 51820 | WireGuard VPN (UDP, default) |
| 1194 | OpenVPN (default) |
Database and cache ports should almost never be open to the whole internet. Restrict them to localhost, a private network or specific IP addresses.