Using NTLM
To use NT LAN Manager (NTLM) (a Windows authentication protocol) with SecureCRT Telnet and Telnet/SSL sessions, you must have a valid Windows security context for NTLM authentication to succeed. Typically, in a Windows network, this means that the local machine and remote server would be members of the same (or trusted) Active Directory Domains. Once a user authenticates to Windows on the client side, the user then has a security context that can be used to authenticate the client to the remote server (assuming that the security context is valid between both the client and server).
As an example, the remote machine must have a username and password associated with the session that is attempting to access the Telnet server. The server's machine must have that same username and password listed under its Users and Passwords facility in the Windows Control Panel.
Note: If a user's password is changed on the local machine, it must also be changed on the Telnet server.
In SecureCRT, NTLM authentication is enabled by default. You can disable NTLM by unchecking the Enable NTLM authentication option on the Session Options/Connection/Telnet dialog.