3.2.5.3.2 Receiving the NTLM_AUTHENTICATE IS Command

Expected AUTH_STATE: challenge_data_sent

On receiving an IS command [NTLM_CommandCode = NTLM_AUTHENTICATE], the server MUST call the local NTLM protocol function for processing the NTLM AUTHENTICATE_MESSAGE. The server MUST then send a REPLY command to the client, and MUST set AUTH_STATE to authentication_complete. The server MUST set the fields of the REPLY command based on the return value from the local NTLM protocol function, as specified in sections 3.2.5.3.2.1 and 3.2.5.3.2.2.

 Neither the mechanism for returning the NTLM_AUTHENTICATE message nor the mechanisms for returning or detecting a failure error code are defined by the Telnet: NTLM Authentication Protocol. These mechanisms are defined by the implementation of the NTLM protocol in use on the server. The server implementation can use any NTLM software.