Negotiating the Protocol

When a new connection is established, the client MUST negotiate capabilities with the server. The client MAY<102> use either of two possible methods for negotiation.

The first is a multi-protocol negotiation that involves sending an SMB message to negotiate the use of SMB2. If the server does not implement the SMB 2 Protocol, this method allows the negotiation to fall back to older SMB dialects, as specified in [MS-SMB].

The second method is to send an SMB2-only negotiate message. This method will result in successful negotiation only for servers that implement the SMB 2 Protocol.