Enumerating Objects in an ActiveDirectory OU via C#

The goal.

My corporation employes Microsoft Active Directory to control (for lack of better word) its users and machines.

I have several computer labs under my control, and I want to list all of the machines in these labs, defined as Organizational Units in my domain's Active Directory.

I want this done via C#.

The straightforward solution.

Use this code:
http://www.codeproject.com/Articles/18102/Howto-Almost-Everything-In-Active-Directory-via-C#19

Which requires an OuDn parameter, which you can find (for your OU of interest) using this tool:
http://technet.microsoft.com/en-us/sysinternals/bb963907.aspx

Voila!

And now for the back story.

I often intend to post stuff in this blog, but then give up. I got to implement some cool stuff lately. But sadly, all of these things were already done better by others, or will be made easier by the framework in the future. One example is branding (that is, matching the language and culture, texts and CSS for users entering your site from different domains). The second is a synchronous service bus. We originally intended to use it until we'll need something "real" such as RabbitMQ; but now it seems we'll resort to using some readymade library anyway.

So this post is not about anything cool, but about something that is 1) terribly annoying and 2) will probably not be improved in its future versions. Why? Because it's delving into the Active Directory of my workplace and extracting some information out. It's Microsoft, it's Active Directory (which is legacy-code all over AFAIK), and it's not intuitive in any way.

Let's make things clear - I am not an expert on Active Directory, nor do I want to be. From my point of view, as a (somewhat privileged) user of this system but not its maintainer here in any way - this is just the odd cloud of Microsoft nonsense that hovers over the network and make authentication work. I was exposed to some of its nice features (such as group policy), but I came to deal with it for a particular reason (more below) and I couldn't care less about its internals until after I get this thing working. With some other technology I would gladly read some documentation or open a book. But in a jungle-o-spaghetti such as Active Directory - no way!

So let's break it down.

After some Googling and executing failing code from different sources, I got to this example - "Howto: (Almost) Everything In Active Directory via C#" by thund3rstruck:
http://www.codeproject.com/Articles/18102/Howto-Almost-Everything-In-Active-Directory-via-C#19

This article from 2008 is still relevant today - more than 5 years later. Note that according to this article, most of the MSDN examples are irrelevant or incorrect. Surprising...

For this code to execute, one must instantiate a DirectoryEntry object:

new DirectoryEntry("LDAP://" + OuDn);

with the OuDn parameter defined like this:

The parameter OuDn is the Organizational Unit distinguishedName such as OU=Users,dc=myDomain,dc=com




As a user I have access the Active Directory Users and Computers tool installed on our server which queries the corporate Active Directory server. I know exactly what I want - an Organizational Unit called "Labs", which contains several OUs - each representing a computer lab, and each of the labs contents - the machines in this lab. But what are the OuDn's for this?

Luckily, some good guys in the SysInternals team came out with this tool - Active Directory Explorer v1.44:http://technet.microsoft.com/en-us/sysinternals/bb963907.aspx

This tool allows you to browse through the Active Directory tree - but it gives you the OuDn's for everything you go through!

Using the OuDn with thund3rstruck's code, I could obtain the list of machines I wanted. And then I could pass them to some PowerShell script which did some maintenance over them. Nice!

As for the code - again, do enter this link:
http://www.codeproject.com/Articles/18102/Howto-Almost-Everything-In-Active-Directory-via-C#19
I used the code exactly as he posted it - I only got the OuDn using the explorer tool.
http://technet.microsoft.com/en-us/sysinternals/bb963907.aspx

Credit for thund3rstruck and to Bryce Cogswell and Mark Russinovich of Microsoft. I just patched things together.