The SMB protocol has been extended with new commands several times since its inception. Each new version is backwards compatible with the previous versions. This makes it quite possible for a LAN to have various clients and servers running different versions of the SMB protocol at once.
Table 3.3 outlines the major versions of the SMB protocol. Within each "dialect" of SMB are many sub-versions that include commands supporting particular releases of major operating systems. The ID string is used by clients and servers to determine what level of the protocol they will speak to each other.
Samba implements the
NT
LM
0.12 specification for NT LAN Manager 1.0. It is backwards compatible with all of the other SMB variants. The CIFS specification is, in reality, LAN Manager 0.12 with a few specific additions.