Книга: Windows Server 2012 R2 Storage, Security, & Networking Pocket Consultant

Understanding SMB changes

Understanding SMB changes

SMB is the primary file sharing protocol used by Windows operating systems. As Windows itself has changed over the years, so has SMB. To allow for version and feature changes, SMB was designed to enable clients and servers to negotiate and then use the highest version supported by both the client attempting to connect an SMB share and the server hosting the share.

The current version of SMB is version 3.02, which is supported by Windows 8.1 and Windows Server 2012 R2. Thus, when a Windows 8.1 computer connects to an SMB share hosted on a server running Windows Server 2012 R2, SMB 3.02 is the version used for the SMB session.

The earliest implementation of SMB was called CIFS, which was introduced with Windows NT 4.0, followed by SMB 1.0, which was used by all versions of Windows from Windows 2000 to Windows Server 2003 R2. Beginning with Windows 8.1 and Windows Server 2012 R2, support for CIFS and SMB 1.0 is an optional feature that must be enabled. Because CIFS and SMB 1.0 are outdated, perform poorly, and are less secure than their predecessors, SMB 1.0/CIFS File Sharing Support should not be enabled unless required. That said, if a computer running Windows 8.1 needs to connect to a server running a legacy Windows operating system, the computer must have the SMB 1.0/CIFS File Sharing Support feature enabled. In addition, if a computer running a legacy Windows operating system needs to connect to a server running Windows Server 2012 R2, the server must have the SMB 1.0/CIFS File Sharing Support feature enabled.

Table 3–1 provides a summary of the current versions of SMB, the associated versions of Windows, and the major features introduced. You can enter Get-SmbConnection at an elevated, administrator Windows PowerShell prompt to determine the version of SMB a client has negotiated with a file server. In the command output, the version is listed in the Dialect column, as shown in the following sample output:

TABLE 3.1 Overview of current SMB versions

IMPORTANT SMB 3.0 and SMB 3.02 brought many enhancements for performance, especially when you use clustered file servers. A key enhancement that doesn’t rely on a special configuration is end-to-end encryption of SMB data, which eliminates the need to use Internet Protocol security (IPsec), specialized hardware, or wide area network (WAN) accelerators to protect data from eavesdropping. SMB encryption can be enabled on a per-share basis.

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