Telnet in Windows

Click "start" → "Control Panel" → "program", "Find and click" open or close windows function "in programs and functions to go to the Windows function Setting dialog box. find and check "Telnet client" and "Telnet Server", and click "OK" to complete the installation. in addition, we can also install "TFTP client" and "Internet Information Service" through this wizard.

After the installation is complete, the telnet service is disabled by default. you also need to run "start" → "run" and enter servcies. MSC (or run "computer"> "management"> "service and application"> "service") to open the Service Manager. find and double-click the telnet service item, set the start mode to "Manual" (more secure, enable only when needed), and then "start" this service "OK" to exit.

Enable telnet echo
First enter the command line interface: Enter Telnet

Next, enter SET localecho.
The system will prompt that local ECHO is enabled
Quit exit

I will first start a local Tomcat as a test
Then enter Telnet localhost 80 in the command line.
Then press Ctrl +], and then press ENTER for nothing,

Then enter the command to see the echo @_@

If you find that the input error is not cleared by the backspace key, you must enter it again,

To view the port in windows, run the netstat command:
Click Start> Run, type cmd, and press enter to open the Command Prompt window. Type "netstat-a-n" in the command prompt. Press the Enter key to view the TCP and UDP connection port numbers and statuses displayed in numbers.

Command Format: netstat? -? ? -E? ? -N? ? -O? ? -S?

-A indicates that all active TCP connections and TCP and UDP ports listened by the computer are displayed.
-E indicates the number of bytes sent and received over the Ethernet, and the number of packets.
-N indicates that only the active TCP connection addresses and port numbers are displayed in numbers.
-O indicates that active TCP connections are displayed and the process ID (PID) of each connection is included ).
-S indicates displaying statistics of various connections by Protocol, including port numbers.

Netstat-An view all open ports
Netstat-N: view the port in the current connection
Close the port
For example, to disable port 25 of the SMTP service in Windows 2000/XP, you can do this: first open "Control Panel", double-click "Administrative Tools", and then double-click "service ". In the displayed service window, find and double-click the "Simple Mail Transfer Protocol (SMTP)" service and click "stop" to stop the service, select "disabled" in "Start type" and click "OK. In this way, closing the SMTP service is equivalent to closing the corresponding port.
Enable Port
If you want to enable this port, you only need to select "Auto" in "Start type", click "OK", and then open the service, in "service status", click "start" to enable the port. Finally, click "OK.

Tip: the "service" option is not available in Windows 98. You can use the firewall rule setting function to disable/enable the port.