Remove a user in domainA from a group in domainB

I'm writing a script in Posh (that seems to be the popular acronym for PowerShell--so I'll go with it as well) that finds all of the inactive users in the domain and moves them to an OU to be disabled one month later if the manager of the user doesn't respond to the email that the script sends.  I finished that part and and now I'm at the point that I disable user accounts where there was no response.

The moving and disabling the users is rather straight forward in Posh. The problem I encounterd was removing the group memberships of the users (a business requirement when we disable the user account).  Now removing the group memberships of groups in the same domain as the user account is also very straight forward, but what happens when you try to remove the user account from a group that is located in a sibling domain in the same forest.
Well here's what happens:

Remove-ADGroupMember : Cannot find an object with identity: 'CN=Smith\, John,OU=Users,OU=location,DC=DomainA,DC=example,DC=com' under: 'DC=DomainB,DC=example,DC=com'.
At line:1 char:21
+ Remove-ADGroupMember <<<<  -Identity $group.ObjectGUID -Members $group.member[12] -Credential $myAdminCreds.DomainB -server DomainB.example.com
    + CategoryInfo          : ObjectNotFound: (CN=Smith\, Joh...,DC=example,DC=com:ADPrincipal) [Remove-ADGroupMember], ADIdentityNotFoundException
    + FullyQualifiedErrorId : SetADGroupMember.ValidateMembersParameter,Microsoft.ActiveDirectory.Management.Commands.RemoveADGroupMember

 All in nice bright red wording.

Here is a script similar to the one that generated that error:

Import-Module ActiveDirectory

$adminCreds = @{domainA = Get-Credential "domA\admin";domainB = Get-Credential "domB\admin"}

$user = Get-ADUser johndoe -Properties memberof -Credential $adminCreds.domainA
$groups = $user.memberof | where{$_ -match "dc=domainB"}

foreach($group in $groups){
    Remove-ADGroupMember -Identity $group -Members $user.distinguishedName -Server domainB.example.com -Credential $adminCreds.domainB
}

Had I chosen groups from domainA, the script would have run without error.

So I posted my problem on every forum I could find including 'The Official Scripting Guys Forum!' as well on #powershell irc chat on freenode.net.  To date no one has responded.  So I delved into a work-a-round.

At first I tried straight up ADSI:

$group = [adsi]"LDAP://$($group.distinguishedName)"
$group.putEx(4,"member",@($user.distinguishedName))
$group.setinfo()

However, because my account is not an administrator in the sibling domain I got an access denied error.  I did a bunch of research again and low-and-behold the best I got was that there is no specific way to provide credentials to a foreign domain with [adsi] (albeit a sibling domain in the same forest).  I even mapped a drive to the domain controller in domainB using my admin credentials in that domain--nadda!

So after a ton of unfruitful research I developed my own work-around. If one of you Posh gurus wants to post an easier way I'd be delighted.  I use WinRM 2.0 to accomplish this (I read a ton of help pages):

Import-Module ActiveDirectory

$adminCreds = @{domainA = Get-Credential "domA\admin";domainB = Get-Credential "domB\admin"}

#Get the user object
$user = Get-ADUser johndoe -Properties memberof -Credential $adminCreds.domainA
#Find groups with distinguishedNames that are in domainB
$groups = $user.memberof | where{$_ -match "dc=domainB"}

#Create a remote session on domainB's domain controller
$s = New-PSSession -ComputerName domb-dc1 -Credential $adminCreds.domainB

<#Unfortunately you can't just reference variables in your local ps session while in the remote session so some setup 
work is needed.  Cycling through the collection of group DNs you first create a hash table (I love hash tables) with 
the parameters you will need to work with in the remote session.#>
foreach($group in $groups){
    $LHparams = @{userDN = $user.distinguishedName;groupDN = $group} #Local Host parameters.
    <#We need to send those parameters to the remote session.  The variable '$multivars' is an arbitrary name. 
    You can use what ever you makes sense in that spot. 'RHparams' Remote Host parameters will be set in the remote pssession.
    $multivars becomes $LHparams and can be used to set a variable on the remote host.  
    
    You can send multiple arguments and must have multiple parameters (param($a, $b))to hold those arguments.
    So this would work:#>
    
    Invoke-Command -Session $s -ScriptBlock {param($rhuserDN, $rhgroupDN) $userDN = $rhuserDN;$groupDN = $rhgroupDN}` 
                                                            -ArgumentList $user.distinguishedName,$group
    
    #However, I like hash tables better-well actually I love hash tables (best thing since sliced bread). so:
    
    Invoke-Command -Session $s -ScriptBlock {param($multivars) $RHparams = $multivars} -ArgumentList $LHparams
    
    <#Now you may be tempted to enter the session in your script--but don't.  My previous post had the script doing that but it
    doesn't work.  The commands issued in the script after entering a PSSession don't do anything.  So do this 
    (check example 5 of Help invoke-command -examples):   #>
    $command = {
        $group = [adsi]"LDAP://$($RHparams.groupDN)"
        $group.putEx(4,"member",@($RHparams.userDN))
        $group.setinfo()
    }
    <#Note that when using the hash table in the remote session the porperties ARE case sensitive.  
    GroupDN gets you nothing groupDN has the data.#>
    
    <#Of course we want as few commands as possible so let's not run the invoke-command twice
    instead let's do this:  #>
    
    $LHparams = @{userDN = $user.distinguishedName;groupDN = $group}
    $command = {
        param($multivars)
        $RHparams = $multivars
        $group = [adsi]"LDAP://$($RHparams.groupDN)"
        $group.putEx(4,"member",@($RHparams.userDN))
        $group.setinfo()
    }
    
    #Now send the commands to the remote session just once.
    Invoke-Command -Session $s -ScriptBlock $command -ArgumentList $LHparams
}

"***The script looks like this without all the extraneous comments***"

#Provided for easier reading of the code.

Import-Module ActiveDirectory

$adminCreds = @{domainA = Get-Credential "domA\admin";domainB = Get-Credential "domB\admin"} #Hash table woohoo!!!
 
$user = Get-ADUser johndoe -Properties memberof -Credential $adminCreds.domainA
$groups = $user.memberof | where{$_ -match "dc=domainB"}

$s = New-PSSession -ComputerName domB-dc1 -Credential $adminCreds.domainB

foreach($group in $groups){
    $LHparams = @{userDN = $user.distinguishedName;groupDN = $group} #another hash table woohoo woohoo!!!
    $command = {
        param($multivars)
        $RHparams = $multivars
        $group = [adsi]"LDAP://$($RHparams.groupDN)"
        $group.putEx(4,"member",@($RHparams.userDN))
        $group.setinfo()
    } 
    Invoke-Command -Session $s -ScriptBlock $command -ArgumentList $LHparams
}

PowerShell Blogging

Well there are a number of really good resources out there for PowerShell and I've been using them frequently. However, I've noticed that not a lot of people are using PowerShell v2 RTM that comes with Windows 7 to manage Active Directory. I'm hoping this can become a place where AD and PowerShell V2 can come together to help administrators take advantage of some of the exciting technologies that are available. I'm new to blogging and I'm a 'newbie' with PowerShell. I've spent the last decade VBScripting all over the place now I'm really focused on learning and taking advantage of all the power PowerShell has to offer.

I have to say to all you VBScripters. PowerShell is really a superior scripting platform. I didn't believe it at first but over the past few weeks I'm convinced that I took way too long to come on over to the PowerShell side of scripting.

My problems with PS were:

1. I don't like curly brackets {}.
2. I didn't like putting $ in front of my variables.
3. I really thought I had to pipe everything. Actually, you don't have to pipe anything if (like me) you don't find that sort of thing intuitive. You can write straight script just like you would in VBScript.
4. Almost forgot--I really didn't like that comparison operators like = < > were replaced with -eq -lt -gt.
   

Those things may seem silly to some, but an honest evaluation of my reasoning produced that list as to why I refused to switch to Posh sooner. Now that I've been using it for about three weeks I'm hooked. It really is a superior scripting language. I find myself being able to do all of the things I did in VB plus more and in a more elegant way. I'm glad I switched.

If like me you have problems with the syntax, I can tell you that if you just start using PowerShell you will get used to the syntax fairly quickly. Now curly brackets don't bother me one bit and I'm already used to the $ variables. So trust me, start using PowerShell, you'll love it.

I figure with this blog I'll post some of my projects and share what I learn as I learn it. Hopefully, it'll be useful to someone out there.

Happy scripting...

Cameron Out.