Friday, March 23, 2012

AD Powershell module and managing multiple domains

One of the things I have noticed every time I try using the Microsoft AD powershell commandlets is that they are not very multi-domain friendly. Most of the commandlets have a -server option where you can point to a server. To do this dynamically, you need to discover a DC with Get-ADDomainController first. However, today I was thinking it would be nice to update permissions cross domain with get-acl/set-acl. Unfortunately, there is no -server option here. From the examples I have seen for managing AD permissions with these two, it uses the AD: PSdrive that gets created when the ActiveDirectory Module is loaded. This default drive points to the domain that your machine is a member of, so this may not be helpful. If you try to use get-acl with this drive and point to a distinguishedName in another domain you will see an error like this:

Get-Acl : A referral was returned from the server

Since AD: is a PSDrive, there is no reason you can't add some more for other domains. Lets say you have two domains, and

New-PSDrive -Name "Child" -Root "" -PsProvider ActiveDirectory -server (Get-ADDomainController -domain -discover -writable).name

This will create a PSDrive called Child:, which will reference this domain. So to work with get-acl you can reference child:"objectdn" to get the acl. For other commandlets, set-location child: and try using these to access objects in it.

If you wanted to auto-create a drive for every domain in your forest you could do this easily (though a bit slowly). PSDrive names are limited in that they cannot contain '.', so in this example I'm just stripping a domain's first portion of its name out:

(get-adforest).domains|foreach {$temp = $_.substring(0,$_.indexof('.')); New-PSDrive -Name $temp -Root "" -PsProvider ActiveDirectory -server (Get-AD
DomainController -domain $_ -discover -writable).name}


After trying to work with the Microsoft AD powershell module for this, and having a lot of problems in a mixed 2008/2003 multidomain environment, I ran into the BSonPosh module. This has a much simpler way of reading and writing ACL's in AD which looks like it will run very easily in a multidomain environement, or non-2008 AD domain. I have a extension to the module to Decode AD ACL.

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