Server Message Block - History

History

Barry Feigenbaum originally designed SMB at IBM with the aim of turning DOS "Interrupt 33" (21h) local file access into a networked file system. Microsoft has made considerable modifications to the most commonly used version. Microsoft merged the SMB protocol with the LAN Manager product which it had started developing for OS/2 with 3Com c. 1990, and continued to add features to the protocol in Windows for Workgroups (c. 1992) and in later versions of Windows.

SMB was originally designed to run on top of the NetBIOS/NetBEUI API (typically implemented with NBF, NetBIOS over IPX/SPX, or NBT). Since Windows 2000, SMB runs, by default, with a thin layer, similar to the Session Message packet of NBT's Session Service, on top of TCP, using TCP port 445 rather than TCP port 139 — a feature known as "direct host SMB".

At around the time when Sun Microsystems announced WebNFS, Microsoft launched an initiative in 1996 to rename SMB to Common Internet File System (CIFS), and added more features, including support for symbolic links, hard links, larger file sizes, and an initial attempt at supporting direct connections over TCP port 445 without requiring NetBIOS as a transport (a largely experimental effort that required further refinement). Microsoft submitted some partial specifications as Internet-Drafts to the IETF, though these submissions have expired.

The Samba project originated with the aim of reverse engineering the SMB protocol and implementing an SMB server to allow MS-DOS clients to use SMB to access files on Sun Microsystems machines. Because of the importance of the SMB protocol in interacting with the widespread Microsoft Windows platform, Samba became a popular free implementation of a compatible SMB client and server for interoperating with non-Microsoft operating systems.

Microsoft introduced SMB2 with Windows Vista in 2006, and later improved on it in Windows 7, with subsequent major revisions of 2.1 and 3.0 as of 2012.