Windows Server Message Block (SMB) Protocol

Versions

There are several different versions of SMB used by Windows operating systems:

SMB Version	Operating System	Note
CIFS	Windows NT	superseded by SMB1
SMB 1.0 (or SMB1)	Windows 2000, XP, Server 2003, Server 2003 R2
SMB 2.0 (or SMB2)	Windows Vista (SP1 or later), Server 2008
SMB 2.1 (or SMB2.1)	Windows 7, Server 2008 R2
SMB 3.0 (or SMB3)	Windows 8, Server 2012
SMB 3.02 (or SMB3)	Windows 8.1, Server 2012 R2	In Windows 8.1 and Server 2012 R2, the option to completely disable CIFS/SMB1 support is introduced. It is not the default configuration.
SMB 3.1.1	Widnows 10, Server 2016

Negotiated Versions

Here’s a table to help you understand what version you will end up using, depending on what Windows version is running as the SMB client and what version of Windows is running as the SMB server:

OS	Windows 8.1 WS 2012 R2	Windows 8 WS 2012	Windows 7 WS 2008 R2	Windows Vista WS 2008	Previous Version
Windows 8.1 WS 2012 R2	SMB 3.02	SMB 3.0	SMB 2.1	SMB 2.0	SMB 1.0
Windows 8 WS 2012	SMB 3.0	SMB 3.0	SMB 2.1	SMB 2.0	SMB 1.0
Windows 7 WS 2008 R2	SMB 2.1	SMB 2.1	SMB 2.1	SMB 2.0	SMB 1.0
Windows Vista WS 2008	SMB 2.0	SMB 2.0	SMB 2.0	SMB 2.0	SMB 1.0
Previous Version	SMB 1.0	SMB 1.0	SMB 1.0	SMB 1.0	SMB 1.0

* WS = Windows Server

Check SMB Version

In Windows 8 or Windows Server 2012 or later, a new PowerShell cmdlet can easily tell what version of SMB the client has negotiated with the File Server. For Windows version prior to Windows 8, there is not an easy way – need to use Network Monitor, Message Analyzer (recommended) or Wireshark to capture and look into the packets.

To check the negotiated SMB version between the client and file server

1. Access a remote file server (or create a new mapping to it)
2. Use Get-SmbConnection

To check the SMB version on the local computer

1. dir \\localhost\c$
2. Get-SmbConnection –ServerName localhost
   • run the Get-SmbConnection cmdlet within 10 seconds after the dir command
   • the SMB client will tear down the connctions if there is no activity

Recommendation

Microsoft strongly encourage to update to the latest of SMB. However, be aware of compatibility with the older Windows operating systems and third-party application implementation.

• VMware
  • vCenter Server Appliance 5.5.x / 6.0.x and vRealize Automation 6.2.x support SMB1 only (KB2134063)

Source

Microsoft Jose Barroeto’s Blog

• Windows Server 2012 R2
• Windows Server 2016