Telnet is a popular protocol used for remotely accessing network devices and servers. By default, Telnet uses port 23 for communication. However, in some situations, it may be necessary to allow Telnet access to a non-standard port, such as when the default port is already in use or when security considerations dictate the use of a non-standard port. In this blog, we will discuss how to allow Telnet access to a non-standard port.
Step 1: Check if the non-standard port is open Before allowing Telnet access to a non-standard port, you need to make sure that the port is open and available for use. You can check the port status using a port scanner tool like Nmap. If the port is closed, you need to open it using your firewall or router settings.
Step 2: Configure Telnet to use the non-standard port To allow Telnet access to a non-standard port, you need to modify the Telnet configuration file. The Telnet configuration file is typically located in the /etc directory and is called telnetd.conf. Open the file in a text editor and look for the line that specifies the Telnet port. By default, this line should read:
port = 23
To allow Telnet access to a non-standard port, you need to change this line to reflect the new port number. For example, if you want to use port 2323, you would change the line to:
port = 2323
Save the changes and exit the editor.
Step 3: Restart the Telnet service After modifying the Telnet configuration file, you need to restart the Telnet service to apply the changes. You can do this using the following command:
sudo systemctl restart telnetd
Alternatively, you can also use the following command:
sudo service telnetd restart
This will restart the Telnet service and apply the changes to the configuration file.
Step 4: Test the Telnet connection To test the Telnet connection to the non-standard port, you can use the Telnet client. Open a terminal window and type the following command:
telnet <server_IP_address> <port_number>
Replace <server_IP_address> with the IP address of the server that you want to connect to and <port_number> with the non-standard port number that you have configured. If the Telnet connection is successful, you should see a prompt asking you to enter your login credentials.
Conclusion Allowing Telnet access to a non-standard port can be useful in certain situations, such as when the default port is already in use or when security considerations dictate the use of a non-standard port. By following the steps outlined in this blog, you can easily configure Telnet to use a non-standard port and test the connection to ensure that everything is working as expected.