Service port意思

"Service port" is a term commonly used in networking and refers to the port number associated with a specific service or application running on a server or device. When you connect to a service, such as HTTP (web browsing), SSH (secure shell for remote login), or FTP (file transfer protocol), you are actually connecting to a specific port on the server that provides that service.

For example, the HTTP service typically runs on port 80, while HTTPS (secure web browsing) runs on port 443. When you enter a website URL into your web browser, your computer is actually communicating with the web server on port 80 (or 443 for secure connections) to retrieve the web pages you request.

Similarly, SSH usually runs on port 22, and FTP can run on port 21 for control and port 20 for data. When you connect to a server using SSH or FTP, you are connecting to the server on these specific ports.

The concept of service ports is important in firewall configuration, as you can allow or deny traffic based on the port numbers associated with different services. For instance, if you want to block external access to FTP servers, you might configure your firewall to block traffic on port 21 (for control) and port 20 (for data).

In summary, a service port is a numerical identifier that is used to distinguish different types of network traffic and to direct incoming requests to the appropriate service running on a server or device.