Service Principals and Azure AD

There are a few scenarios with Azure AD that folks commonly run in to.

I have not blogged about the relationships of an Azure Tenant and Azure AD.  So let me briefly mention the relationship between these two.
(I will be repeating this all in future posts, as this relationship is important to grok)

An Azure Tenant is the Account that you or your company has in Azure.  It is divided into Subscriptions. 
Each Subscription is where you 'consume' in Azure; and it also serves as an isolation boundary (as in, resources in different services can only talk to each other through public entry points - they cannot directly touch each other).
Below that you have Resource Groups, which are management containers (not isolation).
And then you have the actual resources that you get billed for consuming.

All of this together is an Azure Tenant - or phrased another way, you are a Tenant of Azure and this is your playground and thus billing entity.
I will keep using the phrase Azure Tenant in this way.
(I run across MSFT folks that use the word Subscription when referring to the Tenant, and it is just plain incorrect and thus confusing as to the ramifications)

Azure AD is an entirely separate thing.  It is this huge multi-tenant cloud based identity provider, with a number of cool features and touch points.
An Azure Tenant must have an associated Azure AD, but an Azure AD has no dependency on an Azure Tenant (or an Office365 tenant - which is yet another entity).

A single company can have multiple Azure AD's (which is highly likely), they could also have multiple Azure Tenants (which is not very likely, but possible).

A single Azure Tenant can only be associated with one Azure AD.  Nuance here; the tenant has one Azure AD, but people from other Azure ADs can be granted access.  But the invited accounts are foreign accounts.

I bring all of this up since it is this multi-pronged association that usually gets folks into a pickle.

The "Service Principal" is a term that has been within the IT world for a long time.  It describes the user account that a particular application or service runs under.  If that application needs to access resources on the network, the Service Principal user account for that particular service is used.

This has worked well for decades in the enterprise with Active Directory.  And now we need to take this to the cloud.  And it works a bit differently with Azure Active Directory.

Within Azure Active Directory the service principal is called an "App Registration".  And just like with the enterprise, you would have a unique app registration for each application.

This is different than a user account that you simply grant access to Azure resources.  While it really appears to be the same thing, it actually isn't.

Now, as we put things together a number of questions arise.  Which Azure AD should my app registration reside in?  Is there any limitation on the user account?  What resources does the app registration need to access?

Most likely you are using the app registration to interact with your Azure tenant resources.  For example, the app registration is used to provision new machines, or to power machines on and off.  Essentially to perform lifecycle events on your Azure resources.

This means that the app registration must be "native" to the Azure Tenant Azure AD - regardless of what Azure AD your user accounts reside in.  You cannot simply use a random user account.

If you manually create your app registration, you need to be a user administrator in your Azure AD.  And then you can grant the permissions to the Subscription or Resource Groups and you are golden.

https://itproctology.blogspot.com/2017/04/manually-creating-service-principal-for.html

If you are using some other app to create the app registration programmatically things immediately get unique.  All of a sudden your user account matters.

And to programmatically create an app registration, your user account needs to be native to the 

Azure AD.

This is a special kind of native.  The Azure AD account that you use must be an "onMicrosoft" account within that Azure AD.  You cannot use a user account that is synchronized with your on-premises Active Directory.  It does not even matter if your user is a domain admin.

Each Azure AD begins life as an "onMicrosoft" entity.  If you look at the properties of the Azure AD, you will see the information about its original creation, such as brianeh.onmicrosoft.com.  And this remains even if you add a vanity domain, such as ITProctology.com to the Azure AD.

I mention all of this because you might be in a position where you need to create a special Azure AD account, so that your app can create its own app registration (Citrix Cloud does this, RDMI does this).

In your Azure AD, create a new cloud user, using name@domain.onmicrosoft.com  This will create a cloud user that is native only to the Azure AD, and this user will have the full permissions to the API that it needs to create an app registration.

In your app you need to then use the credentials of this new user account so that it can access the API and self create its app registration.

A lot of explanation just to get you to the answer, but the why is often as important as the what.

The gotchas of Azure AD Domain Services in ARM

Not too awful long ago Azure Active Directory Domain Services moved over to the ARM portal from the Azure Classic portal.

Yea! the world said.  And there was much rejoicing.

Now, the real world impacts of this.

There are a few scenarios with Azure AD that folks commonly run in to.

I have not blogged about the relationships of an Azure Tenant and Azure AD.  So let me briefly mention the relationship between these two.
(I will be repeating this all in future posts, as this relationship is important to grok)

An Azure Tenant is the Account that you or your company has in Azure.  It is divided into Subscriptions. 
Each Subscription is where you 'consume' in Azure; and it also serves as an isolation boundary (as in, resources in different services can only talk to each other through public entry points - they cannot directly touch each other).
Below that you have Resource Groups, which are management containers (not isolation).
And then you have the actual resources that you get billed for consuming.

All of this together is an Azure Tenant - your phrased another way, you are a Tenant of Azure and this is your playground and thus billing entity.
I will keep using the phrase Azure Tenant in this way.
(I run across MSFT folks that use the word Subscription when referring to the Tenant, and it is just plain incorrect and thus confusing as to the ramifications)

Azure AD is an entirely separate thing.  It is this huge multi-tenant cloud based identity provider, with a number of cool features and touch points.
An Azure Tenant must have an associated Azure AD, but an Azure AD has no dependency on an Azure Tenant (or an Office365 tenant - which is yet another entity).

A single company can have multiple Azure AD's (which is highly likely), they could also have multiple Azure Tenants (which is not very likely, but possible).

A single Azure Tenant can only be associated with one Azure AD.  Nuance here; the tenant has one Azure AD, but people from other Azure ADs can be granted access.  But the invited accounts are foreign accounts.

Now.  Some background into the processes that get us into the strange places that folks end up in.

When an Azure Tenant is created an Azure AD is created for it.
So you end up with some Azure AD such as you@tenantName.onmicrosoft.com

This is fine.  It gets you up and running and then you add your admins which might be your.admin@yourcomapny.com  and they get invited.  Everything in the Azure Portal works.  Now, lets get into the cases that won't work in this scenario.

This actually puts you in a very common scenario, the scenario where the Azure AD associated with your Azure Tenant is not the same Azure AD where your corporate user accounts reside.

Now, if you only want to use Azure AD RBAC to add your IT folks to the Azure Tenant for administrative purposes, this is fine.  And thus, a more common scenario than most folks want to realize.

Now, lets get to Azure AD Domain Services in ARM.  There is a security boundary here.  The Azure Tenant.  Therefore, when you enable AAD DS in ARM you are restricted to the Azure AD that is associated with the Azure Tenant.

Oh, your Azure Tenant Azure AD is not the one with your users?  Oh my!  How do we resolve this?
(trust me, the sarcasm is real here, I can't tell you how many times I have spoken to folks about this and it takes a while for all the dots to connect before they realize the dilemma).

There are three ways to resolve this:

1. 're-parent' the Azure Tenant.  What does this mean?  It means that you make some other Azure AD the primary Azure AD for your Azure Tenant.  There is an option in the Azure Portal "Move to another Directory".  The impacts:  If you had any RBAC set up, you will break it, and therefore need to set it up all over again.
2. Use a vNet.  When logged on to the Azure AD where the users are, create a new Azure Tenant and subscription.  Turn on AAD DS there.  Then set up a gateway between the vNet in this subscription where your AAD DS and user accounts are, and a vNet in a subscription of the Azure Tenant where your workloads are that require the domain services provided by AAD DS.
3. Don't use AAD DS.  Stand up a Windows Server Domain Service VM (more than one for a proper deployment) and use Azure AD Connect to sync the users with the AD domain.

In the end, this is about your user accounts, the reasons why you wanted AAD DS in the first place (you need NTLM or Kerberos for any reason).

Yes, AAD DS is convenient, but the security models that forced it into this particular assumption is not always in line with reality.

Isolating Citrix Cloud in your Azure Tenant

I have recently been studying issues that customers are having when trying to stand up a proof-of-concept environment for Citrix Cloud in Azure.

Most of these customers are standing up the full XenApp and XenDesktop Service.  However, our Citrix Cloud Services all have the same basic needs for any customer:

1. Azure Subscription (for workers and infrastructure)
2. App Registration (this is an Azure Tenant service account for our cloud based control plane to perform worker lifecycle events within a subscription)
3. Virtual Network (the machines need IP addresses)
4. Active Directory (there is a much larger discussion here, but either a read / write Domain Controller VM  or the Azure Active Directory Domain Service will work)
5. The DNS setting for the Virtual Network must be your Active Directory 
6. Cloud Connector machines (the connection between the machines in the subscription and the control plane)
7. Some type of 'golden' image that is provisioned into the worker machines your end customers get their work done on.

Growing this conversation from the bottom up;

Each customer of Azure has at least one Azure Tenant.

This is your account in Azure.  It is the highest level of connection between Azure and you the customer.

Within your Azure Tenant you have Subscriptions.

Subscriptions are billing boundaries and service boundaries (services within subscription cannot 'talk' to each other without extra work, as if they are in different buildings).

Isolating Citrix Cloud in your tenant;

Can you isolate Citrix Cloud to its own Subscription in your Azure Tenant?  Yes!  And that is actually the topology that I am going to describe here.  How to isolate Citrix Cloud from your corporate infrastructure.

Common project slow down points that I have heard are:  modifications to existing virtual networks and protecting Active Directory.  

Focusing on the Virtual Network issue first;

You CAN create a virtual network dedicated to your Citrix Cloud deployment. 

The important things to remember are:

• You need a route to your Active Directory
• You must update the DNS settings of the Citrix Cloud virtual network to be the AD

The DNS setting is the most common place where customers trip up.  The DNS setting must be set. The Azure default results in the machines not being able to resolve the Active Directory.

The three models as pictures;

It is often that pictures tell a story faster and easier, I wanted to provide those to get you started thinking about your individual topology as well.

If your Active Directory is on the same Virtual Network you are most likely golden.

If your Active Directory machine(s) is on a different Virtual Network in the same subscription, you can use peering between the two virtual networks.

If your Active Directory machine(s) is on a different Virtual Network in a different subscription, you must use a gateway between the two virtual networks.

Virtual Network permissions for Citrix Cloud

In a previous post I covered how to manually create a Service Principal (App registration) for XenDesktop Essentials.  (this also applies to the XenApp and XenDesktop Service)

If you recall, this is the identity that Citrix Cloud will be using when it performs machine lifecycle actions in your Azure Subscription.

Things with permissions can get a bit strange in Azure pretty quickly.  One such area is Virtual Networks.

First of all, a Virtual Network exists within a Subscription.  It can belong to any Resource Group for management, but can be used by any machines or services within the subscription.

Now, in the world of assumptions, this is all fine and easy if you grant the Service Principal account the Contributor role AND the resource group that your virtual network belongs to is within a resource group under that same subscription.  You can take advantage of the inheritance.

This is not always the case.  In fact, it might not be the case for you at all.  You might be putting very tight controls on that Virtual Network to ensure it never gets messed up.

The minimum permissions that the Service Principal needs to your Virtual Network is the VM Contributor Role.  This level of access is necessary for the automated provisioning and lifecycle of desktop or session workers.

If you have a need to grant access to your Virtual Network or want to constrain access to your virtual network, here is how.

Remove the inheritance at the Virtual Network Resource Group from the subscription if it is enabled.
Explicitly grant the App Registration the VM Contributor role on the Virtual Network where worker machines will be attached when provisioned.

You can find more about the permissions in this article that I authored:  Manually granting Citrix Cloud Access to your Azure Subscription

Azure Resource Manager Templates for Citrix Cloud workloads

At Citrix we recognize that different customers need different tools to accomplish their goals.  In the end, it is all about selecting the right tools for your environment and business processes to get you moving forward in an efficient way.

It has been brought to our attention that getting started in Azure with Citrix Cloud is not necessarily as straightforward as it needs to be, especially when customers go it alone (without the aid of a sales engineer or an integrator).

You will be seeing different tools, recommendations, updated documentation, and product enhancements to help get you (the customer) moving forward with your demonstration project, that Proof-of-Concept project, and moving into full production.

One of those tools was recently mentioned on this blog: Citrix Cloud XenDesktop Resource Location ARM Template

Without modification of the template this Azure Resource Manager template is focused on getting you up an going with that very first Demo environment.
It provides everything from an Active Directory Domain to NetScaler VPX.  And the glue in between to make it all work.

Additionally, there are other Azure Resource Manager templates that are componentized to support you in building out the infrastructure in your own way or integrating with your current Azure environment for any of the Citrix Cloud offerings.

These are being built to bring success to your Proof-of-Concept and production deployments. You can find the PoC and Production template repository here: https://github.com/citrix/CitrixCloud-ARMTemplates

This is a community repository and we would love to see your additions and suggestions.

I would also like to hear your stories and questions about using Azure to deploy your Citrix Cloud service, whether it be XenApp Essentials, XenDesktop Essentials, or XenApp and XenDesktop Service. 

Lets make it better together.

Getting started with Citrix Essentials on Azure

Earlier this month two Citrix Essentials products hit the Azure Marketplace;

XenApp Essentials and XenDesktop Essentials. https://www.citrix.com/blogs/2017/04/03/xendesktop-essentials-xenapp-essentials-now-available-in-azure-marketplace/

In this short period of time, there has been  customers who have purchased the services or are kicking the tires.

While I didn't give a number, I can say that it has been a pretty exciting first two weeks, and the interest from customers has been great.  Really great.

Both Essentials offerings run on Azure (exclusively) and are managed through Citrix Cloud.

Since these are new services, the documentation is constantly coming on-line. Here are some references that should get you over the initial hurdles of understanding how to implement it all.

The newly updated XenDesktop Essentials guide: http://docs.citrix.com/en-us/citrix-cloud/xenapp-and-xendesktop-service/xendesktop-essentials.html

If you were wondering if you could take advantage of Azure Active Directory Domain Service? Yes, you can: https://www.citrix.com/blogs/2017/04/11/xenapp-xendesktop-services-support-azure-ad-domain-services/

If you are in a hybrid cloud scenario (user workers in Azure with a VPN back to the datacenter where they need Kerberos or Windows pass-through authentication) you will need to setup up an Active Directory replica server in Azure: https://docs.microsoft.com/en-us/azure/active-directory/active-directory-install-replica-active-directory-domain-controller

Are you setting up Windows Desktops in Azure? 
Be aware that you must implement Azure Active Directory. More details on the way.

And take advantage of the Hybrid Use Benefit Windows 10 image in the Azure Gallery if you create a new golden desktop image.

Active Directory with XenDesktop Essentials in Azure

XenDesktop Essentials and XenApp Essentials have hit the Azure Marketplace, and they are catching on.

For those of you that remember Azure RemoteApp, XenApp Essentials is the replacement for that.  And for those of you that want to give Windows Client desktops to your user-base, XenDesktop Essentials is for that.
And, for those that want it all, There is XenApp and XenDesktop Service.  Which offers it all.

Now, the reason for my post.  Active Directory and Azure Active Directory.
There is a requirement of all of these solutions that the provisioned machines are joined to a domain.  This is where I see many folks getting confused between all of the various Active Directory options.

In reality, there are only two models that will work today (at the date of this post).  Let me describe them in terms of what you need to accomplish.

In both models, you have the user side running in Azure.  Whether that be XenApp Servers (Terminal Servers for you really old folks) or Desktops (Windows Client or Windows Server desktops).

Your answer to this next question defines the path that you need to head down.

Do your Azure based user sessions need to access resources in some other cloud / datacenter?
A different way to ask this - do you need a VPN between your users in Azure and whatever other resources they need to access in some other cloud / datacenter.

If your answer was no; 
Then I am calling you 'cloud born' or 'Azure based'.
Knowing this you can use Azure AD plus Azure Active Directory Domain Service.

AD Sync is built in, and most likely Azure AD is your source for users.  But you need the additional service to support domain join, group policy, and those traditional things that Active Directory provides.

I personally love the following guide for getting AADDS all up and running: Azure Active Directory Domain Services for Beginners

The trick here is that you need to use FQDNs for domain joins and domain references.  If you customize your Azure AD domain, use that.  If you don't it is YourDomain.onmicrosoft.com.

When you need to add Group Policy to lock things down; https://docs.microsoft.com/en-us/azure/active-directory-domain-services/active-directory-ds-admin-guide-administer-group-policy

If your answer was yes;
Then you are more of a 'traditional' enterprise that is in some hybrid deployment model.
Knowing this you need to use Azure AD plus Active Directory.

You will need to enable AD Sync, you will need to establish a replica domain controller in Azure, and you (probably) already have a VPN between your datacenter and Azure virtual network.

The replica domain controller in Azure: https://docs.microsoft.com/en-us/azure/active-directory/active-directory-install-replica-active-directory-domain-controller
Active Directory Sync / Connect to Azure AD: https://docs.microsoft.com/en-us/azure/active-directory/connect/active-directory-aadconnect
(It does not matter where you install / run that, just that you do).

In both cases; Don't forget to update the DNS settings of your Virtual Network with these new machine IP addresses.