Change the Telnet port number

Many friends have asked how to change the Telnet port number. In fact, we have referred to Microsoft's materials for this question. Let's take a look at the specific change measures. I hope you can use this article to master this part of knowledge.

Configure the TCP port number used by the Telnet server

Application to: Windows Server 2008, Windows Vista

You can use this process to change the port number of the Telnet Server Service Listening client request.

By default, the Telnet server listens on TCP port 23. If you change this setting, you must notify the client of the new port number so that the client can include this port number in its request for connection. If you fail to request the correct port number when trying to connect, the connection attempt will fail.

Membership or equivalent identity in the Local Administrators Group is the minimum requirement to complete this process.

To change the number of ports used by the Telnet server

At the command prompt, type the following, and then press Enter:

Tlntadmn [\ server] config port = PortNumber

\ Server

Name of the computer that runs the Telnet server whose port number you want to change. If this parameter does not exist, the command runs based on the Telnet Server Service on the local computer.

Config port = PortNumber

To change the Telnet port number to the value specified by PortNumber.

Format	Description
Italics	REQUIRED INFORMATION
Bold	Elements that must be correctly typed according to the displayed content
Between square brackets ([])	Optional

Other considerations for changing the Telnet port number

Tlntadmn.exe must be run at the command prompt that is opened using the "run as administrator" option. If you do not run the command prompt for permission escalation, you will receive the "Access Denied" message.

The Tlntadmn.exe tool is installed with the Telnet server, so it may not appear on the computer where the Telnet server is not installed.

Run the following command to determine the current port number used by the Telnet server:

Tlntadmn [\ server]

Windows displays multiple current settings, including the port number.