The following describes the common server ports. For more information on service application ports for Windows, refer to the Microsoft Official Documentation (Overview of Windows Services and Network Port Requirements).
| Port | Service | Description |
|---|---|---|
| 21 | FTP | Port opened by the FTP server. It is for uploading and downloading. |
| 22 | SSH | Port 22 is the SSH port used to remotely connect Linux system servers via command-line mode. |
| 25 | SMTP | Port opened by the FTP server. It is for sending mail. |
| 80 | HTTP | It is used to provide external access for website services such as IIS, Apache, and Nginx. |
| 110 | POP3 | Port 110 is open for POP3 (mail protocol 3) services. |
| 137,138,139 | NETBIOS Protocol | Among them, 137 and 138 are UDP ports, which are used when transferring files through the network neighborhood. Port 139: Connections coming through this port attempt to get NetBIOS/SMB services. This protocol is used for Windows file and printer sharing and SAMBA. |
| 143 | IMAP | Port 143 is mainly used for Internet Message Access Protocol v2 (IMAP). Like POP3, it is a protocol for receiving emails. |
| 443 | HTTPS | A web browsing port and another type of HTTP that provides encryption and transmission through secure ports. |
| 1433 | SQL Server | Port 1433 is the default port of the SQL Server, which uses two ports: TCP-1433 and UDP-1434. Port 1433 is used for SQL Server to provide external services, whereas port 1434 is used to respond to the requester regarding which TCP/IP port is being used by SQL Server. |
| 3306 | MySQL | Port 3306, the default port of MySQL database, is used for MySQL to provide external services. |
| 3389 | Windows Server Remote Desktop Services | Port 3389 is the service port for Windows 2000 (2003) Server remote desktop, which allows connection to a remote server using the Remote Desktop connection tool. |
| 8080 | Proxy Port | Similar to port 80, port 8080 is used for the WWW proxy service for web browsing. The port number extension ":8080" is often appended to the URL when users visit a website or use a proxy server. In addition, after the Apache Tomcat web server is installed, the default service port is port 8080. |