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A Closer Look at Azure AD Connect – Part 4

imagesWelcome to the fourth part of this article series about Azure AD Connect. In the previous article, I discussed permissions for a custom installation, and we dived a little deeper into the upgrade capabilities. Before jumping into the 'advanced' customization options such the filtering abilities, I wanted to take a look at some of the additional (preview) features that Azure AD Connect offers to date.

In this article, we'll focus on Azure AD App & attribute filtering as well as the password write-back feature. In part five, we'll explore the various preview features. The support for hybrid deployments and password sync have already been covered in previous articles. 

You can enable additional features in the Azure AD Connect configuration wizard. If you haven't enabled them when installing the tool, you can always re-run the wizard later to enable/disable certain features.

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Image 1: List of Azure AD Connect (optional) features

Azure AD App & Attribute Filtering

The default configuration of Azure AD Connect will synchronize almost all object and object attributes from your Active Directory to Azure AD. This means it might also synchronize object attributes that you do not necessarily need in Office 365. While this isn't necessarily a problem, I imagine that some customers might want to limit what attributes are synchronized to Office 365. High-security environments can be especially 'paranoid' about what gets synchronized to Azure AD.

If the feature is selected, two additional steps are added to the wizard:

  • Azure AD Apps, which allow you to select which services you will be using in Office 365. The following options are available to choose from: Office 365 Pro Plus, Exchange Online, SharePoint Online, Lync (Skype) Online, Azure RMS, Intune, Dynamics CRM or a third-party application. By unselecting the applications you will not be using in Office 365, Azure AD Connect will automatically remove object attributes that are synchronized for the sole purpose of these services. As such, an administrator does not need to keep a list of what attributes are used for what service.
  • Azure AD Attributes allow you to further restrict the attributes that you are synchronizing to Azure AD. Based on what you selected on the Azure AD Apps page, a list of synchronized attributes are shown. Attributes that are mandatory and should not be removed are marked as gray, and you cannot unselect them. This prevents an admin from removing attributes and, as such, causing services to stop working correctly. What happens in the back is that the wizard will remove the attribute from the list of synced attributes in the Azure Active Directory Connector.

For instance, if you remove the ExtentionAttribute15 from the list, it is automatically unselected in the list, too. If you use the Synchronization Service Manager, you can view the properties of the Connector by right-clicking it and selecting properties. Afterward, click Select Attributes:

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Image 2: filtered attribute

Password writeback

The password write-back feature is a very interesting one. It's the perfect way to enable users to change their own password using Azure’s Self-Service Password Reset capabilities AND ensure that the password change is synchronized back into the on-premises Active Directory. This feature can be used in conjunction with Password Hash Synchronization or Active Directory Federation Services.

In the former scenario, it prevents the situation where a password is changed in Office 365 but not in the on-premises environment and, as such, creates an inconsistency between both environments. After password hash synchronization is enabled and the initial "seeding" of the passwords has been completed, only on-premises password changes are synced back to Azure AD. If a user would then be able to change his password in Office 365 (without password write-back enabled), the password would only be changed in Office 365 and thus be out of sync with the on-prem password. If the user then changes his password on-premises, the password in Office 365 is overwritten by the on-prem password, which potentially creates very confusing situations.

The password write-back feature is part of the Azure AD Premium license. You must first ensure that you have enabled premium licenses for your tenant and your users. A trial provides you with 100 licenses, more than enough to test the feature! Enabling the trial is done through the Azure AD portal. You can get to the portal from within the Office 365 Portal and clicking Azure AD under services.

Once you have enabled the trial (or purchased licenses), go to Configure and navigate to the User Password Reset policy section in the Azure AD Portal. If not yet enabled, now would be a good time to enable the Password Reset capability. Note that you may need to assign the Azure AD Premium licenses before this section becomes visible.

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Image 3: activating the password reset capability.

The password reset functionality allows users to proactively change their password or reset passwords when they forget it.

Before you can use the password write-back feature, you must also enable it on the directory synchronization server. After running through the wizard, verify that Password write-back has been successfully enabled on the synchronization server by running the following PowerShell command:

[PS] C:\> Import-Module ADSync
[PS] C:\> Get-ADSyncAADPasswordResetConfiguration -Connector (Get-ADSyncConnector | ? Subtype -eq "Windows Azure Active Directory (Microsoft)").name

After this, ensure that the Azure AD Connect service account has the necessary permissions to reset/change passwords. You can do this using the Active Directory management tools, but it's easier to run the following PowerShell cmdlet from a server, which has the cmd-line utility dsacls.exe installed:

#Enable  Password Hash Synchronization

#Service  Account Name
  $accountName =  "Exchangelab\svc-AADC2"

#Organization  Unit or Domain Tree DN
  $scope =  "DC=Exchangelab,DC=BE"

#Configure  Password Write-Back
  Write-Host "-------------------------------------------"  -ForegroundColor Yellow
  Write-Host "Configuring  Password write-back Permissions" -ForegroundColor  Yellow
  Write-Host "-------------------------------------------"  -ForegroundColor Yellow
  Invoke-Expression "dsacls.exe  '$scope'  /I:S /G `"`"$accountName`":CA;Reset Password;User`" `"`"$accountName`":CA;Change  Password;User`" `"`"$accountName`":WP;LockoutTime;User`" `"`"$accountName`":WP;pwdLastSet;User`""

The scope ($scope) determines whose user passwords can be reset. Technically, it controls to what container (or Organizational Unit) the permissions are applied. From there, permissions are applied to underlying objects, such as user objects. If you have a specific OU which contains the users that are synchronized with Azure AD, feel free to specify that instead. Just make sure to specify it in the Distinguished Name format!

Note: After running the script, it's worth double-checking the permissions in Active Directory. The permissions are propagated down from the object on which they have been applied. If you set the scope to the domain root, but have blocked inheritance on some OUs, the objects under that OU will not have the proper permissions.

Testing the password write-back feature

To reset your password in Office 365, log in to the portal and navigate to the Office 365 settings. From there, select Change your password as illustrated in the image below:

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The user is now taken to a page where he can reset his password. Once the user clicks on Submit, several things happen:

  1. The selected password is encrypted using a special key that was created when the write-back feature was enabled.
  2. The encrypted password is sent over HTTPS to a tenant-specific service bus. This bus is used to communicate with the on-premises Azure AD Connect instance (and write-back service). The communications are additionally protected by a shared password which is only known to Azure and the local installation of Azure AD Connect.
  3. The write-back service in Azure AD Connect then looks for the user account in the on-premises Active Directory. First, it looks up the sourceAnchor (provided in the password reset request) in the connector space. If an object is found, it is traced back through the metaverse all the way to Active Directory.
  4. Once the user object is located, the password is reset – or at least an attempt to reset the password is made. If the reset is successful, the user is notified of it.
  5. If the password reset operation fails, for instance because the password does not match the complexity requirements or because permissions are missing, the user will see an error instead.

As mentioned before, the lack of the correct permissions might cause a password reset to fail. It is important to understand that the on-premises password reset policy controls what passwords you can use and how often you can change it. Even though password synchronization or write-back is set up, Office 365 is not aware of the on-premises password policy. If users try to reset a password that strokes with the on-premises policy, they might get a simple error message, which does not always reveal why the password cannot be reset. Properly informing your users on what they can expect is important, too!

That's it for this part of the article series. As stated earlier, we will take a look at the preview features in part five.

Have fun!

Other articles in this series: