Authentication for Telnet server

For Telnet, it has security problems. Many attacks are caused by it. Therefore, when connecting to the Telnet server, we must use authentication to filter out some disturbing factors. Let's take a closer look at the specific operations.

Configure how the client authenticates the Telnet server

Application to: Windows Server 2008, Windows Vista

You can use this process to configure how the Telnet client authenticates the user account using the Telnet server that connects to the client.

Identity Authentication is a method used to identify and authorize a user. the Telnet server supports two authentication methods: NTLM and plain text. the authentication method tried by the Telnet client must be set in Telnet command mode before you can try remote system authentication. details about the available Authentication mode.

In Telnet command mode, you can display the status of the current NTLM authentication, enable or disable NTLM authentication.

Determine available authentication methods by connecting to the Telnet server. if NTLM authentication is not available, you must use plain text authentication. Otherwise, the connection will fail. you can use this process to configure the client to match the Authentication mode provided by the server. If multiple modes are available at the same time, select the best mode.

Remarks

Changing the Authentication mode when connecting to the Telnet server does not affect the current session. To see the effect of the change, you must disconnect and re-connect to the server.

Any user account can complete this process.

Configure authentication on the Telnet Client

To view or configure the Telnet AUTHENTICATION settings, you can perform the following steps:

Displays the current NTLM authentication status

Enable NTLM Authentication

Enable Password Authentication

Displays the current NTLM authentication status

In the Telnet client service, switch to the command mode. See switch between session mode and command mode.

At the Microsoft Telnet> command prompt, type d and press Enter to display the list of current settings and their values.

The output will include one of the following:

Authentication (NTLM authentication). This indicates that NTLM authentication is enabled.

Authentication is not performed (NTLM authentication). This indicates that NTLM authentication is disabled and the user ID and password will be sent in plain text. This is usually called password authentication.

Enable NTLM Authentication

In the Telnet client service, switch to the command mode. See switch between session mode and command mode.

At the Microsoft Telnet> command line prompt, Enter set ntlm, and then press Enter.

Confirm that NTLM authentication is enabled now. See displaying the current NTLM authentication status

Enable Password Authentication

In the Telnet client service, switch to the command mode. See switch between session mode and command mode.

At the Microsoft Telnet> command line prompt, type unset ntlm, and then press Enter.

Confirm that NTLM authentication is enabled now. See displaying the current NTLM authentication status

Other considerations

Although authentication data may have been encrypted, anyone on the network can read the actually transmitted data. because the Telnet session communication is insecure, make sure that no sensitive data is sent or received during the Telnet session.

If you connect to the computer running the Telnet server by using NTLM authentication, due to NTLM authentication restrictions, you cannot automatically access other network resources. to access other network resources during the Telnet session, you need to provide the user name and password again.