2.2.1.1 NEGOTIATE_MESSAGE

The NEGOTIATE_MESSAGE defines an NTLM Negotiate message that is sent from the client to the server. This message allows the client to specify its supported NTLM options to the server.


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Signature

...

MessageType

NegotiateFlags

DomainNameFields

...

WorkstationFields

...

Version

...

Payload (variable)

...

Signature (8 bytes): An 8-byte character array that MUST contain the ASCII string ('N', 'T', 'L', 'M', 'S', 'S', 'P', '\0').

MessageType (4 bytes): A 32-bit unsigned integer that indicates the message type. This field MUST be set to 0x00000001.

NegotiateFlags (4 bytes): A NEGOTIATE structure that contains a set of flags, as defined in section 2.2.2.5. The client sets flags to indicate options it supports.

DomainNameFields (8 bytes): A field containing DomainName information. The field diagram for DomainNameFields is as follows.


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DomainNameLen

DomainNameMaxLen

DomainNameBufferOffset

If the NTLMSSP_NEGOTIATE_OEM_DOMAIN_SUPPLIED flag is set in NegotiateFlags, indicating that a DomainName is supplied in Payload, the fields are set to the following values:

§ DomainNameLen (2 bytes): A 16-bit unsigned integer that defines the size, in bytes, of DomainName in Payload.

§ DomainNameMaxLen (2 bytes): A 16-bit unsigned integer that SHOULD be set to the value of DomainNameLen, and MUST be ignored on receipt.

§ DomainNameBufferOffset (4 bytes): A 32-bit unsigned integer that defines the offset, in bytes, from the beginning of the NEGOTIATE_MESSAGE to DomainName in Payload.

Otherwise, if the NTLMSSP_NEGOTIATE_OEM_DOMAIN_SUPPLIED flag is not set in NegotiateFlags, indicating that a DomainName is not supplied in Payload, the fields take the following values, and MUST be ignored upon receipt.

  • DomainNameLen and DomainNameMaxLen fields SHOULD be set to zero.

  • DomainNameBufferOffset field SHOULD be set to the offset from the beginning of the NEGOTIATE_MESSAGE to where the DomainName would be in Payload if it was present.

WorkstationFields (8 bytes): A field containing WorkstationName information. The field diagram for WorkstationFields is as follows.


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WorkstationLen

WorkstationMaxLen

WorkstationBufferOffset

If the NTLMSSP_NEGOTIATE_OEM_WORKSTATION_SUPPLIED flag is set in NegotiateFlags, indicating that a WorkstationName is supplied in Payload, the fields are set to the following values:

§ WorkstationLen (2 bytes): A 16-bit unsigned integer that defines the size, in bytes, of WorkStationName in Payload.

§ WorkstationMaxLen (2 bytes): A 16-bit unsigned integer that SHOULD be set to the value of WorkstationLen and MUST be ignored on receipt.

§ WorkstationBufferOffset (4 bytes): A 32-bit unsigned integer that defines the offset, in bytes, from the beginning of the NEGOTIATE_MESSAGE to WorkstationName in Payload.

Otherwise, if the NTLMSSP_NEGOTIATE_OEM_WORKSTATION_SUPPLIED flag is not set in NegotiateFlags, indicating that a WorkstationName is not supplied in Payload, the fields take the following values, and MUST be ignored upon receipt.

  • WorkstationLen and WorkstationMaxLen fields SHOULD be set to zero.

  • WorkstationBufferOffset field SHOULD be set to the offset from the beginning of the NEGOTIATE_MESSAGE to where the WorkstationName would be in Payload if it was present.

Version (8 bytes): A VERSION structure (as defined in section 2.2.2.10) that is populated only when the NTLMSSP_NEGOTIATE_VERSION flag is set in the NegotiateFlags field. This structure SHOULD<6> be used for debugging purposes only. In normal (nondebugging) protocol messages, it is ignored and does not affect the NTLM message processing.

Payload (variable): A byte-array that contains the data referred to by the DomainNameBufferOffset and WorkstationBufferOffset message fields. Payload data can be present in any order within the Payload field, with variable-length padding before or after the data. The data that can be present in the Payload field of this message, in no particular order, are:


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DomainName (variable)

...

WorkstationName (variable)

...

DomainName (variable): If DomainNameLen does not equal 0x0000, DomainName MUST be a byte-array that contains the name of the client authentication domain that MUST be encoded using the OEM character set. Otherwise, this data is not present.<7>

WorkstationName (variable): If WorkstationLen does not equal 0x0000, WorkstationName MUST be a byte array that contains the name of the client machine that MUST be encoded using the OEM character set. Otherwise, this data is not present.

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