The Server Message Block (SMB) network protocol is used to share and access folders, files, printers, and other devices over network (TCP port 445). In this article, we will look at which versions (dialects) of SMB are available in different versions of Windows (and how they relate to samba versions on Linux); how to check the SMB version in use on your computer; and how to enable or disable the SMBv1, SMBv2, and SMBv3 dialects.

SMB Protocol Versions in Windows

There are several versions of the SMB protocol (dialects) that have consistently appeared in new Windows versions (and samba) :

• CIFS – Windows NT 4.0
• SMB 1.0 – Windows 2000
• SMB 2.0 – Windows Server 2008 and Windows Vista SP1 (supported in Samba 3.6)
• SMB 2.1 – Windows Server 2008 R2 and Windows 7 (Samba 4.0)
• SMB 3.0 – Windows Server 2012 and Windows 8 (Samba 4.2)
• SMB 3.02 – Windows Server 2012 R2 and Windows 8.1 (not supported in Samba)
• SMB 3.1.1 – Windows Server 2016 and Windows 10 (not supported in Samba)

In SMB network communication, the client and server use the maximum SMB protocol version supported by both the client and the server.

The summary table of SMB version compatibility looks like this. Using this table, you can determine the version of the SMB protocol that is selected when different versions of Windows interact:

For example, if a client computer running Windows 8.1 connects to a file server with Windows Server 2016, the SMB 3.0.2 protocol will be used.

According to the table, Windows XP and Windows Server 2003 can use only SMB 1.0 to access shared folders and files. The SMBv1 is disabled in newer versions of Windows Server (2012 R2/2016). So, if you are still using Windows XP and Windows Server 2003 devices on your network, they won’t be able to access shared folders on the file server running Windows Server 2016.

If Windows Server 2019/2016 with disabled SMB v1.0 is used as a domain controller, then Windows XP/Server 2003 clients won’t be able to access the SYSVOL and NETLOGON folders on domain controllers and authenticate with AD.

You may receive the following error when trying to connect to a shared folder on a file server with SMBv1 disabled:

The specified network name is no longer available

How to Check SMB Version on Windows?

Let’s look on how to find out which versions of the SMB are enabled on your Windows device.

On Windows 10/8.1 and Windows Server 2019/2016/2012R2, you can check the status of various dialects of the SMB protocol using PowerShell:

Get-SmbServerConfiguration | select EnableSMB1Protocol,EnableSMB2Protocol

This command returned that the SMB1 protocol is disabled (EnableSMB1Protocol = True), and the SMB2 and SMB3 protocols are enabled (EnableSMB1Protocol = False).

On Windows 7, Vista, and Windows Server 2008 R2/2008:

Get-Item HKLM:SYSTEMCurrentControlSetServicesLanmanServerParameters | ForEach-Object {Get-ItemProperty $_.pspath}

If there are no parameters named SMB1 or SMB2 in this registry key, then the SMBv1 and SMBv2 protocols are enabled by default.

Also on these Windows versions, you can check which SMB client dialects are allowed to connect to remote hosts:

sc.exe query mrxsmb10

SERVICE_NAME: mrxsmb10
TYPE : 2 FILE_SYSTEM_DRIVER
STATE : 4 RUNNING
(STOPPABLE, NOT_PAUSABLE, IGNORES_SHUTDOWN)
WIN32_EXIT_CODE : 0 (0x0)
SERVICE_EXIT_CODE : 0 (0x0)
CHECKPOINT : 0x0
WAIT_HINT : 0x0

sc.exe query mrxsmb20

SERVICE_NAME: mrxsmb20
TYPE : 2 FILE_SYSTEM_DRIVER
STATE : 4 RUNNING
(STOPPABLE, NOT_PAUSABLE, IGNORES_SHUTDOWN)
WIN32_EXIT_CODE : 0 (0x0)
SERVICE_EXIT_CODE : 0 (0x0)
CHECKPOINT : 0x0
WAIT_HINT : 0x0

In both cases, the services are running (STATE = 4 Running). This means that the current Windows device can connect to both SMBv1 and SMBv2 hosts.

Checking Used SMB Dialects with Get-SMBConnection

When communicating over SMB, computers use the maximum SMB version supported by both the client and the server. The Get-SMBConnection PowerShell cmdlet can be used to check the SMB version used to access a remote computer:

The SMB version used to connect to the remote server (ServerName) is listed in the Dialect column.

You can display information about the SMB versions used to access a specific server:

Get-SmbConnection -ServerName srvfs01

If you want to display if SMB encryption is in use (introduced in SMB 3.0):

Get-SmbConnection | ft ServerName,ShareName,Dialect,Encrypted,UserName

On the Windows SMB server side, you can display a list of the versions of the SMB protocols that the clients are currently using. Run the command:

Get-SmbSession | Select-Object -ExpandProperty Dialect | Sort-Object -Unique

In this example, there are 898 clients connected to the server using SMB 2.1 (Windows 7/ Windows 2008 R2) and 8 SMB 3.02 clients.

You can use PowerShell to enable auditing of the SMB versions used for the connection:

Set-SmbServerConfiguration –AuditSmb1Access $true

SMB connection events can then be exported from Event Viewer logs:

Get-WinEvent -LogName Microsoft-Windows-SMBServer/Audit

Stop Using the Insecure SMBv1 Protocol

Over the past few years, Microsoft has systematically disabled the legacy SMB 1.0 protocol in all products for security reasons. This is due to the large number of critical vulnerabilities in this protocol (remember the incidents with wannacrypt and petya ransomware, which exploited a vulnerability in the SMBv1 protocol). Microsoft and other IT companies strongly recommend that you stop using SMBv1 in your network.

However, disabling SMBv1 can cause problems with accessing shared files and folders on newer versions of Windows 10 (Windows Server 2016/2019) from legacy clients (Windows XP, Windows Server 2003), third-party OS (Mac OSX 10.8 Mountain Lion, Snow Leopard, Mavericks, old Linux distros), old NAS devices.

If there are no legacy devices left on your network that support only SMBv1, be sure to disable this SMB dialect in Windows.

If you have clients running Windows XP, Windows Server 2003, or other devices that only support SMBv1, they should be updated or isolated.

How to Enable and Disable SMBv1, SMBv2, and SMBv3 on Windows?

Let’s look at ways to enable and disable different SMB versions on Windows. We’ll cover SMB client and server management (they are different Windows components).

Windows 10, 8.1, and Windows Server 2019/2016/2012R2:

Disable SMBv1 client and server:

Disable-WindowsOptionalFeature -Online -FeatureName smb1protocol

Disable SMBv1 server only:

Set-SmbServerConfiguration -EnableSMB1Protocol $false

Enable SMBv1 client and server:

Enable-WindowsOptionalFeature -Online -FeatureName smb1protocol

Enable only SMBv1 server:

Set-SmbServerConfiguration -EnableSMB1Protocol $true

Disable SMBv2 and SMBv3 server:

Set-SmbServerConfiguration -EnableSMB2Protocol $false

Enable SMBv2 and SMBv3 server:

Set-SmbServerConfiguration -EnableSMB2Protocol $true

Windows 7, Vista, and Windows Server 2008 R2/2008:

Disable SMBv1 server:

Set-ItemProperty -Path "HKLM:SYSTEMCurrentControlSetServicesLanmanServerParameters" SMB1 -Type DWORD -Value 0 –Force

Enable SMBv1 server:

Set-ItemProperty -Path "HKLM:SYSTEMCurrentControlSetServicesLanmanServerParameters" SMB1 -Type DWORD -Value 1 –Force

Disable SMBv1 client:

sc.exe config lanmanworkstation depend= bowser/mrxsmb20/nsi
sc.exe config mrxsmb10 start= disabled

Enable SMBv1 client:

sc.exe config lanmanworkstation depend= bowser/mrxsmb10/mrxsmb20/nsi
sc.exe config mrxsmb10 start= auto

Disable SMBv2 server:

Set-ItemProperty -Path "HKLM:SYSTEMCurrentControlSetServicesLanmanServerParameters" SMB2 -Type DWORD -Value 0 -Force

Enable SMBv2 server:

Set-ItemProperty -Path "HKLM:SYSTEMCurrentControlSetServicesLanmanServerParameters" SMB2 -Type DWORD -Value 1 –Force

Disable SMBv2 client:

sc.exe config lanmanworkstation depend= bowser/mrxsmb10/nsi
sc.exe config mrxsmb20 start= disabled

Enable SMBv2 client:

sc.exe config lanmanworkstation depend= bowser/mrxsmb10/mrxsmb20/nsi
sc.exe config mrxsmb20 start= auto

You can disable SMBv1 server on domain joined computers by deploying the following registry parameter through the GPO:

• Key: HKEY_LOCAL_MACHINESYSTEMCurrentControlSetServicesLanmanServerParameters
• Name: SMB1
• Type: REG_DWORD
• Value: 0

Set the registry parameter SMB2=0 in order to disable the SMBv2 server.

To disable the SMBv1 client, you need to propagate the following registry setting:

• Key: HKEY_LOCAL_MACHINESYSTEMCurrentControlSetservicesmrxsmb10
• Name: Start
• Type: REG_DWORD
• Value: 4