Use an Azure file share with Windows

• 06/07/2018
• 11 minutes to read
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Azure Files is Microsoft's easy-to-use cloud file system. Azure file shares can be seamlessly used in Windows and Windows Server. This article discusses the considerations for using an Azure file share with Windows and Windows Server.

In order to use an Azure file share outside of the Azure region it is hosted in, such as on-premises or in a different Azure region, the OS must support SMB 3.0.

You can use Azure file shares on a Windows installation that is running either in an Azure VM or on-premises. The following table illustrates which OS versions support accessing file shares in which environment:

¹Windows Server 2019 is available in preview through the Windows Server Insiders program. Although Windows Server 2019 is not supported for production use yet, please let us know if you have any issues connecting to Azure file shares beyond what is covered in the troubleshooting guide for Windows.
²Windows 10, versions 1507, 1607, 1703, 1709, and 1803.
³Windows Server, version 1709 and 1803.

Prerequisites

• Storage account name: To mount an Azure file share, you will need the name of the storage account.

• Storage account key: To mount an Azure file share, you will need the primary (or secondary) storage key. SAS keys are not currently supported for mounting.

• Ensure port 445 is open: The SMB protocol requires TCP port 445 to be open; connections will fail if port 445 is blocked. You can check to see if your firewall is blocking port 445 with the Test-NetConnection cmdlet. Remember to replace your-storage-account-name with the relevant name for your storage account.

  Test-NetConnection -ComputerName <your-storage-account-name>.core.windows.net -Port 445
  

  If the connection was successful, you should see the following output:

  ComputerName     : <storage-account-host-name>
  RemoteAddress    : <storage-account-ip-address>
  RemotePort       : 445
  InterfaceAlias   : <your-network-interface>
  SourceAddress    : <your-ip-address>
  TcpTestSucceeded : True
  

  Note

  The above command returns the current IP address of the storage account. This IP address is not guaranteed to remain the same, and may change at any time. Do not hardcode this IP address into any scripts, or into a firewall configuration.

Using an Azure file share with Windows

To use an Azure file share with Windows, you must either mount it, which means assigning it a drive letter or mount point path, or access it via its UNC path.

Unlike other SMB shares you may have interacted with, such as those hosted on a Windows Server, Linux Samba server, or NAS device, Azure file shares do not currently support Kerberos authentication with your Active Directory (AD) or Azure Active Directory (AAD) identity, although this is a feature we are working on. Instead, you must access your Azure file share with the storage account key for the storage account containing your Azure file share. A storage account key is an administrator key for a storage account, including administrator permissions to all files and folders within the file share you're accessing, and for all file shares and other storage resources (blobs, queues, tables, etc) contained within your storage account. If this is not sufficient for your workload, Azure File Sync may address the lack of Kerberos authentication and ACL support in the interim until AAD-based Kerberos authentication and ACL support is publicly available.

A common pattern for lifting and shifting line-of-business (LOB) applications that expect an SMB file share to Azure is to use an Azure file share as an alternative for running a dedicated Windows file server in an Azure VM. One important consideration for successfully migrating a line-of-business application to use an Azure file share is that many line-of-business applications run under the context of a dedicated service account with limited system permissions rather than the VM's administrative account. Therefore, you must ensure that you mount/save the credentials for the Azure file share from the context of the service account rather than your administrative account.

Persisting Azure file share credentials in Windows

The cmdkey utility allows you to store your storage account credentials within Windows. This means that when you try to access an Azure file share via its UNC path or mount the Azure file share, you will not need to specify credentials. To save your storage account's credentials, run the following PowerShell commands, replacing <your-storage-account-name> and <your-resoure-group-name> where appropriate.

$resourceGroupName = "<your-resource-group-name>"
$storageAccountName = "<your-storage-account-name>"

# These commands require you to be logged into your Azure account, run Login-AzureRmAccount if you haven't
# already logged in.
$storageAccount = Get-AzureRmStorageAccount -ResourceGroupName $resourceGroupName -Name $storageAccountName
$storageAccountKeys = Get-AzureRmStorageAccountKey -ResourceGroupName $resourceGroupName -Name $storageAccountName

# The cmdkey utility is a command-line (rather than PowerShell) tool. We use Invoke-Expression to allow us to 
# consume the appropriate values from the storage account variables. The value given to the add parameter of the
# cmdkey utility is the host address for the storage account, <storage-account>.file.core.windows.net for Azure 
# Public Regions. $storageAccount.Context.FileEndpoint is used because non-Public Azure regions, such as sovereign 
# clouds or Azure Stack deployments, will have different hosts for Azure file shares (and other storage resources).
Invoke-Expression -Command "cmdkey /add:$([System.Uri]::new($storageAccount.Context.FileEndPoint).Host) " + `
    "/user:AZURE\$($storageAccount.StorageAccountName) /pass:$($storageAccountKeys[0].Value)"

You can verify the cmdkey utility has stored the credential for the storage account by using the list parameter:

cmdkey /list

If the credentials for your Azure file share are stored successfully, the expected output is as follows (there may be additional keys stored in the list):

Currently stored credentials:

Target: Domain:target=<storage-account-host-name>
Type: Domain Password
User: AZURE\<your-storage-account-name>

You should now be able to mount or access the share without having to supply additional credentials.

Advanced cmdkey scenarios

There are two additional scenarios to consider with cmdkey: storing credentials for another user on the machine, such as a service account, and storing credentials on a remote machine with PowerShell remoting.

Storing the credentials for another user on the machine is very easy: when logged into your account, simply execute the following PowerShell command:

$password = ConvertTo-SecureString -String "<service-account-password>" -AsPlainText -Force
$credential = New-Object System.Management.Automation.PSCredential -ArgumentList "<service-account-username>", $password
Start-Process -FilePath PowerShell.exe -Credential $credential -LoadUserProfile

This will open a new PowerShell window under the user context of your service account (or user account). You can then use the cmdkey utility as described above.

Storing the credentials on a remote machine using PowerShell remoting is not however possible, as cmdkey does not allow access, even for additions, to its credential store when the user is logged in via PowerShell remoting. We recommend logging into the machine with Remote Desktop.

Mount the Azure file share with PowerShell

Run the following commands from a regular (i.e. not an elevated) PowerShell session to mount the Azure file share. Remember to replace <your-resource-group-name>, <your-storage-account-name>, <your-file-share-name>, and <desired-drive-letter> with the proper information.

$resourceGroupName = "<your-resource-group-name>"
$storageAccountName = "<your-storage-account-name>"
$fileShareName = "<your-file-share-name>"

# These commands require you to be logged into your Azure account, run Login-AzureRmAccount if you haven't
# already logged in.
$storageAccount = Get-AzureRmStorageAccount -ResourceGroupName $resourceGroupName -Name $storageAccountName
$storageAccountKeys = Get-AzureRmStorageAccountKey -ResourceGroupName $resourceGroupName -Name $storageAccountName
$fileShare = Get-AzureStorageShare -Context $storageAccount.Context | Where-Object { 
    $_.Name -eq $fileShareName -and $_.IsSnapshot -eq $false
}

if ($fileShare -eq $null) {
    throw [System.Exception]::new("Azure file share not found")
}

# The value given to the root parameter of the New-PSDrive cmdlet is the host address for the storage account, 
# <storage-account>.file.core.windows.net for Azure Public Regions. $fileShare.StorageUri.PrimaryUri.Host is 
# used because non-Public Azure regions, such as sovereign clouds or Azure Stack deployments, will have different 
# hosts for Azure file shares (and other storage resources).
$password = ConvertTo-SecureString -String $storageAccountKeys[0].Value -AsPlainText -Force
$credential = New-Object System.Management.Automation.PSCredential -ArgumentList "AZURE\$($storageAccount.StorageAccountName)", $password
New-PSDrive -Name <desired-drive-letter> -PSProvider FileSystem -Root "\\$($fileShare.StorageUri.PrimaryUri.Host)\$($fileShare.Name)" -Credential $credential -Persist

If desired, you can dismount the Azure file share using the following PowerShell cmdlet.

Remove-PSDrive -Name <desired-drive-letter>

Mount the Azure file share with File Explorer

1. Open File Explorer. This can be done by opening from the Start Menu, or by pressing Win+E shortcut.

2. Navigate to the This PC item on the left-hand side of the window. This will change the menus available in the ribbon. Under the Computer menu, select Map network drive.

   

3. Copy the UNC path from the Connect pane in the Azure portal.

   

4. Select the drive letter and enter the UNC path.

   

5. Use the storage account name prepended with AZURE\ as the username and a storage account key as the password.

   

6. Use Azure file share as desired.

   

7. When you are ready to dismount the Azure file share, you can do so by right-clicking on the entry for the share under the Network locations in File Explorer and selecting Disconnect.

Accessing share snapshots from Windows

If you have taken a share snapshot, either manually or automatically through a script or service like Azure Backup, you can view previous versions of a share, a directory, or a particular file from file share on Windows. You can take a share snapshot from the Azure Portal, Azure PowerShell, and Azure CLI.

List previous versions

Browse to the item or parent item that needs to be restored. Double-click to go to the desired directory. Right-click and select Properties from the menu.

Select Previous Versions to see the list of share snapshots for this directory. The list might take a few seconds to load, depending on the network speed and the number of share snapshots in the directory.

You can select Open to open a particular snapshot.

Restore from a previous version

Select Restore to copy the contents of the entire directory recursively at the share snapshot creation time to the original location.

Securing Windows/Windows Server

In order to mount an Azure file share on Windows, port 445 must be accessible. Many organizations block port 445 because of the security risks inherent with SMB 1. SMB 1, also known as CIFS (Common Internet File System), is a legacy file system protocol included with Windows and Windows Server. SMB 1 is an outdated, inefficient, and most importantly insecure protocol. The good news is that Azure Files does not support SMB 1, and all supported versions of Windows and Windows Server make it possible to remove or disable SMB 1. We always strongly recommend removing or disabling the SMB 1 client and server in Windows before using Azure file shares in production.

The following table provides detailed information on the status of SMB 1 each version of Windows:

Auditing SMB 1 usage

Applies to Windows Server 2019 (preview), Windows Server semi-annual channel (versions 1709 and 1803), Windows Server 2016, Windows 10 (versions 1507, 1607, 1703, 1709, and 1803), Windows Server 2012 R2, and Windows 8.1

Before removing SMB 1 in your environment, you may wish to audit SMB 1 usage to see if any clients will be broken by the change. If any requests are made against SMB shares with SMB 1, an audit event will be logged in the event log under Applications and Services Logs > Microsoft > Windows > SMBServer > Audit.

To enable auditing, execute the following cmdlet from an elevated PowerShell session:

Set-SmbServerConfiguration –AuditSmb1Access $true

Removing SMB 1 from Windows Server

Applies to Windows Server 2019 (preview), Windows Server semi-annual channel (versions 1709 and 1803), Windows Server 2016, Windows Server 2012 R2

To remove SMB 1 from a Windows Server instance, execute the following cmdlet from an elevated PowerShell session:

Remove-WindowsFeature -Name FS-SMB1

To complete the removal process, restart your server.

Removing SMB 1 from Windows client

Applies to Windows 10 (versions 1507, 1607, 1703, 1709, and 1803) and Windows 8.1

To remove SMB 1 from your Windows client, execute the following cmdlet from an elevated PowerShell session:

Disable-WindowsOptionalFeature -Online -FeatureName SMB1Protocol

To complete the removal process, restart your PC.

Disabling SMB 1 on legacy versions of Windows/Windows Server

Applies to Windows Server 2012, Windows Server 2008 R2, and Windows 7

SMB 1 cannot be completely removed on legacy versions of Windows/Windows Server, but it can be disabled through the Registry. To disable SMB 1, create a new registry key SMB1 of type DWORD with a value of 0 under HKEY_LOCAL_MACHINE > SYSTEM > CurrentControlSet > Services > LanmanServer > Parameters.

You can easily accomplish this with the following PowerShell cmdlet as well:

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

After creating this registry key, you must restart your server to disable SMB 1.

SMB resources

• Stop using SMB 1
• SMB 1 Product Clearinghouse
• Discover SMB 1 in your environment with DSCEA
• Disabling SMB 1 through Group Policy

Next steps

See these links for more information about Azure Files:

• Planning for an Azure Files deployment
• FAQ
• Troubleshooting on Windows