How to detect, enable and disable SMBv1, SMBv2, and SMBv3 in Windows and Windows Server

Applies to: Windows 10 Pro released in July 2015Windows Vista EnterpriseWindows Vista Business More

Summary


This article describes how to enable and disable Server Message Block (SMB) version 1 (SMBv1), SMB version 2 (SMBv2), and SMB version 3 (SMBv3) on the SMB client and server components. 
 

In Windows 7 and Windows Server 2008 R2, disabling SMBv2 deactivates the following functionality:
  • Request compounding - allows for sending multiple SMB 2 requests as a single network request
  • Larger reads and writes - better use of faster networks
  • Caching of folder and file properties - clients keep local copies of folders and files
  • Durable handles - allow for connection to transparently reconnect to the server if there is a temporary disconnection
  • Improved message signing - HMAC SHA-256 replaces MD5 as hashing algorithm
  • Improved scalability for file sharing - number of users, shares, and open files per server greatly increased
  • Support for symbolic links
  • Client oplock leasing model - limits the data transferred between the client and server, improving performance on high-latency networks and increasing SMB server scalability
  • Large MTU support - for full use of 10-gigabye (GB) Ethernet
  • Improved energy efficiency - clients that have open files to a server can sleep
In Windows 8, Windows 8.1, Windows 10, Windows Server 2012, and Windows Server 2016, disabling SMBv3 deactivates the following functionality (and also the SMBv2 functionality that's described in the previous list):
  • Transparent Failover - clients reconnect without interruption to cluster nodes during maintenance or failover
  • Scale Out – concurrent access to shared data on all file cluster nodes 
  • Multichannel - aggregation of network bandwidth and fault tolerance if multiple paths are available between client and server
  • SMB Direct – adds RDMA networking support for very high performance, with low latency and low CPU utilization
  • Encryption – Provides end-to-end encryption and protects from eavesdropping on untrustworthy networks
  • Directory Leasing - Improves application response times in branch offices through caching
  • Performance Optimizations - optimizations for small random read/write I/O

More Information


The SMBv2 protocol was introduced in Windows Vista and Windows Server 2008.

The SMBv3 protocol was introduced in Windows 8 and Windows Server 2012.

For more information about the capabilities of SMBv2 and SMBv3 capabilities, go to the following Microsoft TechNet websites:
 

How to gracefully remove SMB v1 in Windows 8.1, Windows 10, Windows 2012 R2, and Windows Server 2016


Windows Server 2012 R2 & 2016: PowerShell methods

SMB v1

Detect:

Get-WindowsFeature FS-SMB1

Disable:

Disable-WindowsOptionalFeature -Online -FeatureName smb1protocol

Enable:

Enable-WindowsOptionalFeature -Online -FeatureName smb1protocol


SMB v2/v3

Detect:

Get-SmbServerConfiguration | Select EnableSMB2Protocol

Disable:

Set-SmbServerConfiguration -EnableSMB2Protocol $false

Enable:

Set-SmbServerConfiguration -EnableSMB2Protocol $true



Windows Server 2012 R2 and Windows Server 2016: Server Manager method for disabling SMB

SMB v1
Server Manager - Dashboard method



Windows 8.1 and Windows 10: PowerShell method

SMB v1 Protocol



Windows 8.1 and Windows 10: Add or Remove Programs method

Add-Remove Programs client method
 
 

How to detect status, enable, and disable SMB protocols on the SMB Server


For Windows 8 and Windows Server 2012

Windows 8 and Windows Server 2012 introduce the new Set-SMBServerConfiguration Windows PowerShell cmdlet. The cmdlet enables you to enable or disable the SMBv1, SMBv2, and SMBv3 protocols on the server component. 


You do not have to restart the computer after you run the Set-SMBServerConfiguration cmdlet.

SMB v1 on SMB Server
Detect: Get-SmbServerConfiguration | Select EnableSMB1Protocol
Disable: Set-SmbServerConfiguration -EnableSMB1Protocol $false
Enable: Set-SmbServerConfiguration -EnableSMB1Protocol $true

For more information, see Server storage at Microsoft.

SMB v2/v3 on SMB Server
Detect: Get-SmbServerConfiguration | Select EnableSMB2Protocol
Disable: Set-SmbServerConfiguration -EnableSMB2Protocol $false
Enable: Set-SmbServerConfiguration -EnableSMB2Protocol $true


For Windows 7, Windows Server 2008 R2, Windows Vista, and Windows Server 2008

To enable or disable SMB protocols on an SMB Server that is running Windows 7, Windows Server 2008 R2, Windows Vista, or Windows Server 2008, use Windows PowerShell or Registry Editor.

PowerShell methods


SMB v1 on SMB Server

Detect:

Get-Item HKLM:\SYSTEM\CurrentControlSet\Services\LanmanServer\Parameters | ForEach-Object {Get-ItemProperty $_.pspath}

Default configuration = Enabled (No registry key is created), so no SMB1 value will be returned

Disable:

Set-ItemProperty -Path "HKLM:\SYSTEM\CurrentControlSet\Services\LanmanServer\Parameters" SMB1 -Type DWORD -Value 0 –Force

Enable:

Set-ItemProperty -Path "HKLM:\SYSTEM\CurrentControlSet\Services\LanmanServer\Parameters" SMB1 -Type DWORD -Value 1 –Force


Note You must restart the computer after you make these changes.

For more information, see Server storage at Microsoft.

SMB v2/v3 on SMB Server

Detect:

Get-ItemProperty HKLM:\SYSTEM\CurrentControlSet\Services\LanmanServer\Parameters | ForEach-Object {Get-ItemProperty $_.pspath}


Disable:

Set-ItemProperty -Path "HKLM:\SYSTEM\CurrentControlSet\Services\LanmanServer\Parameters" SMB2 -Type DWORD -Value 0 –Force


Enable:

Set-ItemProperty -Path "HKLM:\SYSTEM\CurrentControlSet\Services\LanmanServer\Parameters" SMB2 -Type DWORD -Value 1 –Force


Note You must restart the computer after you make these changes.


Registry Editor

Important This article contains information about how to modify the registry. Make sure that you back up the registry before you modify it. Make sure that you know how to restore the registry if a problem occurs. For more information about how to back up, restore, and modify the registry, click the following article number to view the article in the Microsoft Knowledge Base:
322756 How to back up and restore the registry in Windows

To enable or disable SMBv1 on the SMB server, configure the following registry key:

Registry subkey: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\LanmanServer\Parameters
Registry entry: SMB1
REG_DWORD: 0 = Disabled
REG_DWORD: 1 = Enabled
Default: 1 = Enabled (No registry key is created)

To enable or disable SMBv2 on the SMB server, configure the following registry key:

Registry subkey:HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\LanmanServer\Parameters
Registry entry: SMB2
REG_DWORD: 0 = Disabled
REG_DWORD: 1 = Enabled
Default: 1 = Enabled (No registry key is created)


Note You must restart the computer after you make these changes.

How to detect status, enable, and disable SMB protocols on the SMB Client


For Windows Vista, Windows Server 2008, Windows 7, Windows Server 2008 R2, Windows 8, and Windows Server 2012

Note When you enable or disable SMBv2 in Windows 8 or in Windows Server 2012, SMBv3 is also enabled or disabled. This behavior occurs because these protocols share the same stack.

SMB v1 on SMB Client
Detect: sc.exe qc lanmanworkstation
Disable: sc.exe config lanmanworkstation depend= bowser/mrxsmb20/nsi
sc.exe config mrxsmb10 start= disabled
Enable: sc.exe config lanmanworkstation depend= bowser/mrxsmb10/mrxsmb20/nsi
sc.exe config mrxsmb10 start= auto


For more information, see Server storage at Microsoft

SMB v2/v3 on SMB Client
Detect: sc.exe qc lanmanworkstation
Disable: sc.exe config lanmanworkstation depend= bowser/mrxsmb10/nsi
sc.exe config mrxsmb20 start= disabled
Enable: sc.exe config lanmanworkstation depend= bowser/mrxsmb10/mrxsmb20/nsi
sc.exe config mrxsmb20 start= auto


Notes

  • You must run these commands at an elevated command prompt.
  • You must restart the computer after you make these changes.

Disable SMBv1 Server with Group Policy


This procedure configures the following new item in the registry:


HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\LanmanServer\Parameters

Registry entry: SMB1 REG_DWORD: 0 = Disabled


To configure this by using Group Policy:

  1. Open the Group Policy Management Console. Right-click the Group Policy object (GPO) that should contain the new preference item, and then click Edit.
  2. In the console tree under Computer Configuration, expand the Preferences folder, and then expand the Windows Settings folder.
  3. Right-click the Registry node, point to New, and select Registry Item.

    Registry - New - Registry Item

In the New Registry Properties dialog box, select the following:

  • Action: Create
  • Hive: HKEY_LOCAL_MACHINE
  • Key Path: SYSTEM\CurrentControlSet\Services\LanmanServer\Parameters
  • Value name: SMB1
  • Value type: REG_DWORD
  • Value data: 0

New Registry Properties - General

This disables the SMBv1 Server components. This Group Policy must be applied to all necessary workstations, servers, and domain controllers in the domain.

Note WMI filters can also be set to exclude unsupported operating systems or selected exclusions, such as Windows XP. 

Disable SMBv1 Client with Group Policy


To disable the SMBv1 client, the services registry key needs to be updated to disable the start of MRxSMB10 and then the dependency on MRxSMB10 needs to be removed from the entry for LanmanWorkstation so that it can start normally without requiring MRxSMB10 to first start.

This will update and replace the default values in the following 2 items in the registry:


HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\services\mrxsmb10

Registry entry: Start REG_DWORD: 4 = Disabled

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\LanmanWorkstation

Registry entry: DependOnService REG_MULTI_SZ: “Bowser”,”MRxSmb20″,”NSI”


Note The default included MRxSMB10 which is now removed as dependency


To configure this by using Group Policy:

  1. Open the Group Policy Management Console. Right-click the Group Policy object (GPO) that should contain the new preference item, and then click Edit.
  2. In the console tree under Computer Configuration, expand the Preferences folder, and then expand the Windows Settings folder.
  3. Right-click the Registry node, point to New, and select Registry Item.

Registry - New - Registry Item

In the New Registry Properties dialog box, select the following:

  • Action: Update
  • Hive: HKEY_LOCAL_MACHINE
  • Key Path: SYSTEM\CurrentControlSet\services\mrxsmb10
  • Value name: Start
  • Value type: REG_DWORD
  • Value data: 4

Start Properties - General

Then remove the dependency on the MRxSMB10 that was just disabled

In the New Registry Properties dialog box, select the following:

  • Action: Replace
  • Hive: HKEY_LOCAL_MACHINE
  • Key Path: SYSTEM\CurrentControlSet\Services\LanmanWorkstation
  • Value name: DependOnService
  • Value type REG_MULTI_SZ
  • Value data:
    • Bowser
    • MRxSmb20
    • NSI

Note These three strings will not have bullets (see the following screen shot).

DependOnService Properties

The default value includes MRxSMB10 in many versions of Windows, so by replacing them with this multi-value string, it is in effect removing MRxSMB10 as a dependency for LanmanServer and going from four default values down to just these three values above.

Note When you use Group Policy Management Console, you don't have to use quotation marks or commas. Just type the each entry on individual lines.

Restart required

After the policy has applied and the registry settings are in place, the targeted systems must be restarted before SMB v1 is disabled.

Summary

If all the settings are in the same Group Policy Object (GPO), Group Policy Management displays the following settings.

Group Policy Management Editor - Registry

Testing and validation

After these are configured, allow the policy to replicate and update. As necessary for testing, run gpupdate /force at a command prompt, and then review the target computers to make sure that the registry settings are applied correctly. Make sure SMB v2 and SMB v3 is functioning for all other systems in the environment.