SMB3 PowerShell changes in Windows Server 2012 R2: SMB1 can now be completely removed

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Introduction 

Windows Server 2012 R2 introduced a new version of SMB. Technically it’s SMB version 3.02, but we continue to call it just SMB3. The main changes are described at https://technet.microsoft.com/en-us/library/hh831474.aspx.

With this new release, we made a few changes in SMB PowerShell to support the new scenarios and features. This includes a few new cmdlets and some changes to existing cmdlets, with extra care not break any of your existing scripts.

This blog post outlines one of the 7 set of changes related to SMB PowerShell in Windows Server 2012 R2.

  

SMB1 can now be completely removed

 

In Windows Server 2012 R2, SMB1 became an optional component and can now be completely disabled, so that the associated binaries are not even loaded. For scenarios where SMB1 is not required, this means less resource utilization, less need for patching and improved security.

For instance, in the Hyper-V over SMB scenario, where you are storing Hyper-V virtual disks and virtual machine configuration in SMB file shares, SMB3 is a requirement. In this case, SMB1 is not necessary and can be safely disabled.

For information worker scenarios, if you have Windows XP clients, you absolutely still need SMB1, since that is the only SMB version supported by Windows XP. If *all* your clients are running Windows Vista or later, SMB1 is no longer required and you can disable SMB1. Windows Vista and Windows 7 do not need SMB1 since they support SMB2. Windows 8 and Windows 8.1 do not need SMB1, since they support both SMB2 and SMB3.

For classic server scenarios, if you have Windows Server 2003 or Windows Server 2003 R2 servers, you absolutely still need SMB1, since that is the only SMB version supported by them. Windows Server 2008 and Windows Server 2008 R2 do not need SMB1 since they support SMB2. Windows Server 2012 and Windows Server 2012 R2 do not need SMB1, since they support both SMB2 and SMB3.

 

Disable SMB1

 

Even though the component can now be removed, due to the compatibility issues listed above, it is still enabled by default.

 

To disable SMB1 completely, use the following PowerShell cmdlet:

  • Remove-WindowsFeature FS-SMB1

 

You can re-enable it by using:

  • Add-WindowsFeature FS-SMB1

 

Notes

 

1) A reboot is required after this feature is enabled or disabled.

2) For more details about SMB versions and dialects and which operating systems support them, see https://blogs.technet.com/b/josebda/archive/2013/10/02/windows-server-2012-r2-which-version-of-the-smb-protocol-smb-1-0-smb-2-0-smb-2-1-smb-3-0-or-smb-3-02-you-are-using.aspx

3) This blog post is an updated version of the September 2013 post at  https://blogs.technet.com/b/josebda/archive/2013/09/03/what-s-new-in-smb-powershell-in-windows-server-2012-r2.aspx focused on a single topic.