Server Message Block (SMB) 2.0

Server Message Block (SMB), also known as the Common Internet File System (CIFS), is the file sharing protocol used by default on Windows-based computers. Windows includes an SMB client (the Client For Microsoft Windows feature installed through the properties of a network connection) and an SMB server (the File And Printer Sharing For Microsoft Windows feature installed through the properties of a network connection). SMB in versions of Windows prior to Windows Server 2008 and Windows Vista, known as SMB 1.0, was originally designed in the early 1990s for early Windows-based network operating systems, such as Microsoft LAN Manager and Windows for Workgroups, and carries with it the limitations of its initial design.

Windows Server 2008, Windows Vista, and Windows 7 also support SMB 2.0, a new version of SMB that has been redesigned for today's networking environments and the needs of the next generation of file servers. SMB 2.0 has the following enhancements:

1. Supports sending multiple SMB commands within the same packet. This reduces the number of packets sent between an SMB client and server, a common complaint against SMB 1.0.
2. Supports much larger buffer sizes compared to SMB 1.0.
3. Increases the restrictive constants within the protocol design to allow for scalability. Examples include an increase in the number of concurrent open file handles on the server and the number of file shares that a server can have.
4. Supports durable handles that can withstand short interruptions in network availability.
5. Supports symbolic links.

Computers running Windows Server 2008, Windows Vista, or Windows 7 support both SMB 1.0 and SMB 2.0. SMB 2.0 can be used only if both the client and server support it, however. Therefore, both the client and the server must be using SMB 2.0 to benefit from the improvements. Windows Vista and Windows 7 support complete backward compatibility with SMB 1.0 and earlier versions of Windows.

As with other versions of Windows, server-side support for SMB (sharing files and printers) is provided by the Server service, and client-side support (connecting to shared resources) is provided by the Workstation service. Both services are configured to start automatically, and you can safely disable either service if you don't require it. The security risks presented by having the Server service running are minimized because Windows Firewall will block incoming requests to the Server service on public networks by default.