The strongest in history? From 0 to 33600 Logical Port Details (1)

        In network technology, a port has two meanings: one is a physical port, for example, an ADSL modem, a hub, a switch, or an interface used by a router to connect to other network devices, such as an RJ-45 port or an SC port. and many more. The second is the logical port, which generally refers to the port in the TCP/IP protocol. The port number ranges from 0 to 65535, such as port 80 for browsing web services, port 21 for FTP services, and so on. What is going to be introduced here is the logical port.

View Port

To view the port in Windows 2000/XP/Server 2003, you can use the Netstat command:

Click Start→Run, type cmd and press Enter. , open a command prompt window. Type "netstat -a -n" at the command prompt and press the Enter key to see the port number and status of the TCP and UDP connections displayed in numeric form.

Turning off/on port

Before introducing the functions of various ports, let me introduce how to close/open ports in Windows, because by default, there are many unsafe or No useful ports are enabled, such as port 23 of the Telnet service, port 21 of the FTP service, port 25 of the SMTP service, port 135 of the RPC service, and so on. In order to ensure the security of the system, we can close/open the port by the following method.

Shut down the port

For example, to close the 25 port of the SMTP service in Windows 2000/XP, you can do this: first open the "Control Panel", double-click "Administrative Tools", then double-click "Services" . Then find and double-click the "Simple Mail Transfer Protocol (SMTP)" service in the open service window, click the "Stop" button to stop the service, then select "Disabled" in the "Startup Type", and finally click "OK" "The button is OK. Thus, closing the SMTP service is equivalent to closing the corresponding port.

Open Port

If you want to open the port, just select "Automatic" in "Startup Type", click "OK" button, then open the service, in the "Service Status" Click the "Start" button to enable the port, and finally, click the "OK" button.

Tip: There is no "service" option in Windows 98, you can use the firewall's rule settings feature to close /open the port.