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When you use Telnet to map a drive letter to a network share, the procedure may not work and the following error message may be displayed:

A specified logon session does not exist. It may already have been terminated.
NOTE : This problem does not affect Telnet sessions for which the user authentication method is clear text.

CAUSE
This issue occurs when you open a Telnet session to a computer running Windows NT Server using the NTLM authentication method. You cannot then, from within the Telnet session, connect to network resources using your implied user credentials. You must explicitly specify your credentials when making network connections from within the Telnet session.

There is no mechanism in Windows NT to perform delegation of security (pass through) for network logon attempts.

For example, if you log on to the network using NTLM from computer A to computer B, and then type "net use" at a command prompt to connect to computer C from computer B, the connection is not made. The reason is that computer B has an incomplete user token (it does not have your password), so the logon attempt to computer C does not work. This behavior is rooted in NTLM being a challenge/response protocol, and as such, it avoids sending your password across the network.

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