Azure Files and AD DS – Part 1

Azure Files and AD DS – Part 1

Welcome back folks.

I recently had a few customers reach out to me with questions around Azure Files integration with Windows Active Directory Domain Services (AD DS). Since I had never used it, I decided to build a small lab and test the functionality and better understand the service. In this series I’ll be walking through what the functionality provides, how I observed it working, and how to set it up.

In any enterprise you will have a number of Windows file shares hosting critical corporate data. If you’ve ever maintained or supported those file shares you’re quite familiar with the absolute sh*t show that occurs across an organization with the coveted H drive is no longer accessible. Maintaining a large cluster of Windows Servers backing corporate file shares can be significantly complex to support. You have your upgrades, patches, needs to scale, failures with DFS-R (distributed file system replication) or FRS-R (file replication service replication) for some of you more unfortunate souls. Wouldn’t it be wonderful if all that infrastructure could be abstracted and managed by someone else besides you? That is the major value proposition of Azure Files.

Azure Files is a PaaS (platform-as-a-service) offering provided by Microsoft Azure that is built on top of Azure Storage. It provides fully managed file shares over a protocol you know and love, SMB (Server Message Block). You simply create an Azure File share within an Azure Storage account and connect to the file share using SMB from a Windows, Linux, or MacOS machine.

Magic right? Well what about authentication and authorization? How does Microsoft validate that you are who you say you are and that you’re authorized to connect to the file share? That my friends will be what we cover from this point on.

Azure File shares supports methods of authentication:

  1. Storage account access keys
  2. Azure AD Domain Services
  3. AD DS (Active Directory Domain Services)

Of the three methods, I’m going cover authentication using AD DS (which I’ll refer to as Windows AD).

Support for Windows AD with Azure Files graduated to general availability last month. As much as we’d like it to not be true, Windows AD and traditional SMB file shares will be with us many years to come. This is especially true for enterprises taking the hybrid approach to cloud, which is a large majority of the customer base I work with. The Windows AD integration allows organizations to leverage their existing Windows AD identities for authentication and protect the files using Windows ACLs (access control lists) they’ve grown to love. This provides a number of benefits:

  • Single sign-on experience for users (via Kerberos)
  • Existing Windows ACLs can be preserved if moving files to a Azure File share integrated with Windows AD
  • Easier to supplement existing on-premises file servers without affecting the user experience
  • Better support for lift and shift workloads which may have dependencies on SMB
  • No infrastructure to manage
  • Support for Azure File Sync which allows you to store shares in Azure Files and create cache on Windows Servers

There are a few key dependencies and limitations I want to call out. Keep in mind you’ll want to visit the official documentation as these will change over time.

  • The Windows AD identities you want to use to access the file shares must be synchronized to Azure AD (we’ll cover the why later)
  • The storage account hosting the Azure File share must be in the same tenant you’re syncing the identities to
  • Linux VMs are not supported at this time
  • Services using the computer account will not be able to access an Azure File share so plan on using a traditional service account (aka User account) instead
  • Clients accessing the file share must be Window 7/Server 2008 R2 ore above
Lab Environment

So I’ve given you the marketing pitch, let’s take a look at the lab environment I’ll be using for this walkthrough.

For my lab I’ve provisioned three VMs (virtual machines) in a VNet (virtual network). I have a domain controller which provides the jogcloud.local Windows AD forest, an Azure AD Connect server which is synchronizing users to the jogcloud Azure AD tenant, and a member server which I’ll use to access the file share.

In addition to the virtual machines, I also have an Azure Storage account where I’ll create the shares. I’ve also configured a PrivateLink Endpoint which will allow me to access the file share without having to traverse the Internet. Lastly, I have an Azure Private DNS zone hosting the necessary DNS namespace needed to handle resolution to my Private Endpoint. I won’t be covering the inner workings of Azure Private DNS and Private Endpoints, but you can read my series on how those two features work together here.

In my next post I’ll dive in how to setup the integration, walk through some Wireshark and Fiddler captures, and walk through some of the challenges I ran into when running through this lab for this series.

See you next post!