The following describes the common server ports. For more information about service application ports for Windows, see the official Microsoft document (Windows Service Overview and Network Port Requirements).
|21||FTP||An open FTP server port for uploading and downloading.|
|22||SSH||Port 22 is the SSH port. It is used to remotely connect to Linux system servers in CLI mode.|
|25||SMTP||SMTP server's open port for sending emails.|
|80||HTTP||This port is used for web services such as IIS, Apache, and Nginx to provide external access.|
|110||POP3||Port 110 is open for the POP3 (email protocol 3) service.|
|137, 138, 139||NetBIOS protocol||Ports 137 and 138 are UDP ports for transferring files via My Network Places.
Port 139: Connections over port 139 attempt to access the NetBIOS/SMB service. This protocol is used for file and printer sharing on Windows and SAMBA.
|143||IMAP||Port 143 is mainly used for Internet Message Access Protocol (IMAP) v2, a protocol for receiving emails akin to POP3.|
|443||HTTPS||Web browsing port. This is another type of HTTP that provides encryption and transmission over secure ports.|
|1433||SQL Server||Port 1433 is the default port for SQL Server. The SQL Server service uses two ports: TCP-1433 and UDP-1434. Port 1433 is used for SQL Server to provide external services, while port 1434 is used to respond the requester that which TCP/IP port is being used by SQL Server.|
|3306||MySQL||Port 3306, the default port for MySQL databases, is used by MySQL to provide external services.|
|3389||Windows Server Remote Desktop Services||Port 3389 is the service port for remote desktop on Windows 2000/2003 Server, through which you can connect to a remote server by 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. Port number ":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.|