Powershell – Rename domain computer remotely (within an active directory domain as well)
I wanted to rename a couple of computers within our active directory. After some research i figured out thats it seems to be nearly impossible to rename a computer by just touching one object: the ad computer object, or the computer (client) itself. My first thought was "ok, you have to rename both objects, rejoin the computer and hope everything works". But that's no solution, that makes me happy, because the more steps you do, the more problems can occure. For examples, what happens if the computer has to reboot, after renaming to get correct rejoined? Do i have to create a local admin account at the clientside to have permissions after the computer lost his connection to ad? And so on...
I played around, renamed the ad object, rebooted it - negative, the computer has to be joined again. After that i tried it the "bottom up" way by renaming the computer by hand, and rebooted it instantly. While the computer was shutting down i noticed, that the computerobject in active directory was renamed before the computer was finished with its shutdown process.
So i tried this several times and every time the ad computerobject was renamed properly. YAY!
I had my solution. It can't get more easy to rename a computer without rejoining it.
After this conclusion i tried to do it remotly with powershell, so i googled and found some sites about using netdom.exe. But, yep, right, calling a remote program was not the way i want to solve this problem 
. I found some information on using wmi that suits me, so i started writing a powershell script to test it. As expected it's a bit complicated to rename a computer within a domain by wmi. You have to overcome 3 "hurdles":
- Use Authentication
- Using username and passwort of an administrative account
- Reboot the computer instantly after renaming
Here is a script, that does everything you want. Rename the computer and reboot it if renaming was successfull. Look at line 32 and fill in your admin credentials (~domain admin)
#############################################################################################
# Parameterlist
#############################################################################################
param([string] $computername,$newcomputername)
#############################################################################################
# POWERSHELL Ping tool to check if a computer/ip/hostname is online
#############################################################################################
function isComputerOnline( $comp ){
trap [Exception] {
return $false
}
if ( $(new-object system.net.networkinformation.ping).send( $comp ).status -eq "Success" )
{
return $true
}else{
return $false
}
}
#############################################################################################
# Remote Rename Computer by WMI
#############################################################################################
function COMPUTER_RENAME([string] $oldComputerName, [string] $newComputerName){
# should implement further checks for the computername. If computername uses illegal characters and if computername is longer than 15 characters
# More information here: http://labmice.techtarget.com/articles/computernaming.htm
$oldComputerName = $oldComputerName.replace(" ","");
$newComputerName = $newComputerName.replace(" ","");
# // Check if the computer is online
if ( isComputerOnline $oldComputerName ){
# // Check the active directory if a computer with your provided newcomputername already exists.
# // If you want to use the script without active directory just comment (use: #) this line and the corresponding "else" loop
if ( ! (Get-ADObject -ldapfilter "(CN=$newComputerName)") ){
# // Handle every upcoming error as a stop failure, so you can trap it
$ErrorActionPreference = "Stop"
try{
# // Get the WMI Object of the remote computer
$ComputerWMIObject = Get-WmiObject Win32_ComputerSystem -ComputerName "$oldComputerName" -Authentication 6
if ( $ComputerWMIObject ){
# // Rename the Computer Object with your or some admin credentials (Yes, Passwort is the second parameter and username the third )
$result = $ComputerWMIObject.Rename("$newComputerName","[PASSWORD]","[USERNAME]")
# // Switch Case for the returnvalue of computer renaming function
switch($result.ReturnValue)
{
0 {
# // Reboot the computer instantly if renaming was successfull
Get-WmiObject Win32_OperatingSystem -ComputerName "$oldComputerName" |
ForEach-Object {$restart = $_.Win32Shutdown(6)}
write-host "Computer $oldComputerName was renamed ($newComputerName) and restarted"
}
5 { write-host "Computer was not renamed. Please check if you have admin permissions (ReturnCode 5)"; exit; }
default { write-host "ReturnCode $($result.ReturnValue)"; exit;}
}
}else{
write-host "Couldn't create WMI Object on $oldComputerName"
}
}catch{
write-host $_
}
}else{
write-host "There is already a computerobject with the name $($newComputerName)"
}
}else{
write-host "Computer is offline!"
}
}
if ( $computername -and $newcomputername ){
COMPUTER_RENAME $computername $newcomputername
}else{
write-host ""
write-host "Script Usage:
.ps1 -computername ""Current-Computer-Name"" -newcomputername ""New-Computer-Name"""
write-host ""
}
To use this script just copy the source code to a .txt file and rename it to [whateverYouWant].ps1.
Now start your Powershell and go to the directory where your script is and start it with the following command:
.\myrenamescript.ps1 -computername "CurrentCompName" -newcomputername "NewCompName"
There is no check on the computername yet, so every computername you submit is more or less valid.
More information about the limitations of a computername can be found here: http://support.microsoft.com/kb/909264/en-us
Feel free to use this script and leave me a comment!
Active Directory – Supersonic and the directory searcher
Whats the difference between supersonic and the directory searcher? Nothing, because if you get over ~1000 you crash into a wall.
Last week we had to deal with the limitations on the directory searcher.
We performed a user search on an organizational unit (subtree) with more than 1000 users beneath. We where astonished that our userobject only contained 1000 items every time we did the search. I wrote a little test script in powershell to reproduce this behaviour and to see if this limitation is a C# problem or not.
So I wrote this script:
import-module activedirectory
$intCounter = 0
$objDomain = New-Object System.DirectoryServices.DirectoryEntry
$objSearcher = New-Object System.DirectoryServices.DirectorySearcher
$objSearcher.SearchRoot = $objDomain
$objSearcher.Filter = ("(objectclass=user)")
$colResults = $objSearcher.FindAll()
foreach ( $objResult in $colResults ) {$intCounter = $intCounter + 1}
write-host "Found $intCounter entries"
As expected, powershell returned only 1000 objects. Then we tried to find out why and looked at the $objSearcher property list.
$objSearcher | get-member
As you can see, there are two interesting properties: sizelimit and pagesize. So I played around with these two properties and found some explanations for them. Sizelimit is the limit for the maximum returned results, but you can't set this property above 1000. So I looked at the second property, pagesize. This property sets the maximum result items per returned page. So all you have to do is, set sizelimit to 0 and set pagesize to 1000 and you will get all of your items.
import-module activedirectory
$intCounter = 0
$objDomain = New-Object System.DirectoryServices.DirectoryEntry
$objSearcher = New-Object System.DirectoryServices.DirectorySearcher
$objSearcher.SearchRoot = $objDomain
$objSearcher.sizelimit = 0
$objSearcher.pagesize = 1000
$objSearcher.Filter = ("(objectclass=user)")
$colResults = $objSearcher.FindAll()
foreach ( $objResult in $colResults ) {$intCounter = $intCounter + 1}
write-host "Found $intCounter entries"
If you set pagesize to 1000 and expect more than 1000 returned items the active directory returns your first 1000 items, then pause for a split and returns the next x items and so on until all found items are returned. This property has a appreciable impact on your searchresult duration.
After some research I found some tutorials on how to increment these limitations in the active directory, but i don't know what impact such a change would have, so i can live with the pagesize property 
Windows XP – Offer Remote Desktop Assistance with predefined ip
If you want to automate the remote desktop assistance (not remote desktop) with Windows XP you run into some problems. First of all I ran into the problem that "rcimlby.exe", which seems to be a good point to start lacks with its commandline parameter. I thought that "rcimlby.exe" has a hidden parameter to submit a computer netbios name, or a ipaddress to connect directly to the computer after launching the application, but after debugging the exe I didn't find any indication for a computerobject parameter, so I started to look elsewhere and found a pretty simple solution.
As it turns out, rcimlby.exe calls a help website (Windows XP help) from where you can start a remote desktop assistance. But this website hasn't a parameter for the computerobject as well and it seems to be impossible to call this website within the help explorer, so I traced the way rcimlby.exe calls this website and found this call:
c:\WINDOWS\pchealth\helpctr\binaries\helpctr.exe -FromStartHelp -url hcp://CN=Microsoft%20Corporation,L=Redmond,S=Washington,C=US/Remote%20Assistance/Escalation/Unsolicited/UnSolicitedRCUI.htm
But there is no way to add a parameter for the computerobject, so I started to find out where these weird (and never used 
) html helpfiles are stored (especially where UnSolicitedRCUI.htm is stored)
SCCM – Delete computer object via powershell and wmi [edit]
After one hour of research i found a solution on how to delete a computer object in sccm from a remote computer via Powershell. First of all you need to get the computer object from your sccm namespace "ROOT\SMS\site_[yoursite] -> SMS_R_SYSTEM.
All machine items are stored in SMS_R_SYSTEM, so i used a wmi query with a filter to get the object i need.
There are several ways you can get the computer object, another example is a WMI query, that returns the object.
// Powershell $compObject = get-wmiobject -query "select * from SMS_R_SYSTEM WHERE Name='[computername]'" -computername [sccm-server] -namespace "ROOT\SMS\site_[yoursite]"
You should check if the $compObject is empty or not and if not you can just use psbase to delete the object from the sccm server completly (not only from the collection) by using this statement
// Powershell $compObject.psbase.delete()
How to deal with multiple objects [edit]
Special thanks to Leeni, who wrote a comment at this post on how to deal with multiple entries at your SCCM server. If your WMI query returns more than one object you have to handle this a bit different.
To check if your query returned more than one object try this:
$compObject.psbase.length
or
$compObject.psbase.syncroot
Both properties are only set if your result contains more than one object, so you can easily check if these objects are empty or not.
If they are not empty you have to delete your $compObject this way
$compObject.psbase.syncroot | % { $_.delete() }
This pipes your syncroot object to a foreach loop (% is an alias for foreach) and delete every object one after another.