This is an original Core Protocol command.

This command is used to initiate an SMB connection between the client and the server. An SMB_COM_NEGOTIATE exchange MUST be completed before any other SMB messages are sent to the server.

There MUST be only one SMB_COM_NEGOTIATE exchange per SMB connection. Subsequent SMB_COM_NEGOTIATE requests received by the server MUST be rejected with error responses. The server MUST NOT take any other action.