Virtualization, Cloud, Infrastructure and all that stuff in-between

My ramblings on the stuff that holds it all together

Category Archives: Active Directory

Designing Active Directory – Talk by Brian Desmond in London


If you’re in the UK and are interested in Active Directory – Brian Desmond (an MVP for AD) will be giving a talk on Active Directory design on 29th October in London.

Details here on the ADUG website here and – registration is free.

I’ve been working with Active Directory for a long time but it’s always refreshing to have some Q&A with industry peers, so if you can make it it promises to be an interesting evening.

Not sure if it will be recorded/streamed for people that can’t make it – if not can I make that suggestion to the ADUG team- I can bring some recording equipment if you need it.

Redesigning Active Directory for 2010 and on..


Active Directory has been implemented as part of Windows since approx 1998 when the betas of the initial Windows 2000 version were circulating. At the time directory services was Microsoft’s answer to all NT4 scalability woes and the superior management that Novell offered in Netware 4.x, that was a radically different IT world {cue Waynes world flash back}

  • Most people worked in a set of fixed locations, mobile workers were by far the minority
  • Those fixed locations had full all-ports network access to corporate resources internal network and/or personal firewalls were unheard of.
  • People who needed remote access to the network came in by dial-up or VPN type access with token or user/password type authentication
  • Starbucks was NOT your office 🙂
  • your PC/laptop was owned by the company and you had less need to keep your personal on-line life running during work time or using work-resources (you shopped in real shops and people still used the phone to communicate)
  • Viruses were there but the most prevalent forms propagated by infected documents and emails.
  • Network connectivity was slow and/or expensive from remote locations

I’ve worked with Active Directory in a lot of depth during this time and it’s an excellent and flexible tool, however it’s now 2009 and whilst Active Directory has been enhanced over this time it isn’t radically different in terms of supporting the way we work today.

There is still a very tight integration* between a workstation (domain member) and the Domain/Forest – this relies on periodical machine account password changes.

  • All authentication and group policy type activities like interactive logon, policy downloads etc. still require a large number of ports and RPC services to function – this makes firewalls like swiss-cheese, and doesn’t work well in locations with latent or slow network connections (although there are tweaks; most of these involve turning off GPO processing on slow links).
  • To provide remote access to domain and corporate services a VPN layer is required to provision access, this is ok but a large part of the Windows interactive logon process still requires access to a domain controller at the CTRL-ALT-DEL logon screen – support for this is hacky at best when you are not on a full all-ports open network connection to the corporate domain – 3rd parties have custom GINA code that allows you to initiate a VPN connection before the logon is processed but it’s not a one-stop shop and users still *just don’t get it*.
  • Disconnected machines (like roaming sales people) rely heavily on cached credentials, these credentials are only refreshed when you make an interactive logon to the corporate network – which requires VPN, large number of port rules; machine hygiene routines etc.
  • User profiles/folder redirections don’t work particularly well in long-term disconnected scenarios and it’s difficult to maintain a consistent user profile environment for these users.

If you’ve ever had to re-build a user’s machine whilst disconnected from the network this can be a real issue.

*Machines can only be part of one domain at a time, they rely heavily on it for authentication and control.

Building standalone/workgroup machines is one answer but you have no way of managing any of the machines, tracking them, distributing configurations etc. – there is too much all or nothing and there is no middle ground in Active Directory at present – and this also makes multi-tier firewalled application platforms problematic – do you put in multiple domains to support tiers/DMZ’s or compromise security and use a single domain and wider firewall rules? if you put in workgroup machines manging security across all of them is problematic, some Microsoft products (Exchange, etc.) require an Active Directory domain and change is difficult.

In addition, high-speed Internet access is now very common and the move to “the cloud” is underfoot, with end-user devices being little more than very clever terminals.

Microsoft have made moves to support single sign on through web applications with the Active Directory Federation Services (AD-FS) in Windows 2008 but this is still geared at web applications rather than the core authentication and application services Microsoft’s desktop and server OS relies on for normal operations.

This is a list of the things I would like to see in future Active Directory and/or add-on endpoint security checkers to better support the upcoming generations of users who won’t always be on the corporate LAN, or purchase and use their own PC/laptop as well as the needs that virtualization and dynamic scaling infrastructure requires.

  • Move authentication services to HTTP/S interfaces and away from RPC and dynamic ports.
  • Make the group policy services available over the same HTTP/S interfaces
  • This has already been done for Outlook/Exchange via the RPC over HTTP/S interface – Active Directory could use a similar concept for allowing access from external/edge services.
  • Introduce a further class of machine to compliment the traditional “computer” account; an “external managed machine” (or similar) – where it isn’t necessarily a direct member of the domain but you allow a degree of trust – maybe leveraging the AD Federation Services, no local passwords held but hashed with the core AD service with an intermediate service (or core-OS component) to facilitate authentication between applications and the AD to maintain backwards compatibility for anything that runs locally and relies on traditional Windows authentication.
  • Allow all communication between these external managed devices and core infrastructure over HTTP/S – so as to be tolerant of latent connections and carried over common network services.
  • Allow those managed external machines to be locally administered/installed/maintained etc. (think of the Windows Mobile Phone or iPhone model that is used to allow access to Exchange email but give it a representative object in Active Directory that can be managed through policies or even disabled – even if that object is just a certificate for the device or some other representation it should be accessible through the AD tools and scripting interfaces.
  • Add support for configuration compliance scanning for external managed devices (end-point security) and centralised reporting – some of this is in next gen ISA tools.
  • Support for transient (often virtual..) machines that are dynamically added to a domain and removed – think of the VDI model where hundreds of machines could be created and destroyed automatically – leaving hundreds of “dead” machine accounts and reboots to support the domain join operations.
  • Support and manage a corporate PC “out on the Internet" as if it were in the office (..using web services/HTTP wrappers) much like we can with Outlook 2003+ and Exchange 2003+ using RPC over HTTP/s – no complicated and difficult to use local VPN client

What would you like to see?

As an addendum; Apologies for the lack of posting recently on which has been due to the arrival of our second child, which as you might imagine has taken up a lot of my blogging time! hopefully will get a bit more time in the coming months to support my habit!