list all SPNs used in your Active Directory

There are a lot of hints & tips out there for troubleshooting SPNs (service principal names).

Listing duplicate SPNs is fairly easy, use the “setspn -X” command and you’ll find out.

But how do you find out which SPNs are used for which users and computers are used for this?

Quite some scripts  you find on the net assume you’re looking for a specific SPN (HTTP/… ) or a specific user or a specific computer…

Like using setspn to find SPNs linked to a certain computer

setspn -L <ServerName>

Like using setspn to find SPNs linked to a certain user account

setspn -L <domain\user>

The old school system admins go for LDIFDE, like

Ldifde -d "DC=Contoso,DC=Com" -l ServicePrincipalName -F C:\SPN.txt

or

Ldifde -f spnaccount.txt -r serviceprincipalname=*/servername* -l serviceprincipalname,samaccountname

Just recently I got a case where we need to clean up some SPNs, but the configuration was not documented.
The SPNs were unknown, and the user accounts and server names … eh spread all over the place…

So I needed a general script to list all SPNs, for all users and all computers…

Nice fact to know, SPNs are set as an attribute on the user or computer accounts.
So that makes it fairly ease to query for that attribute.

And modern admins do PowerShell, right?

Here you go!

#Set Search
cls
$search = New-Object DirectoryServices.DirectorySearcher([ADSI]“”)
$search.filter = “(servicePrincipalName=*)”
$results = $search.Findall()

#list results
foreach($result in $results)
{
$userEntry = $result.GetDirectoryEntry()
Write-host “Object Name = “ $userEntry.name -backgroundcolor “yellow” -foregroundcolor “black”
Write-host “DN      =      “  $userEntry.distinguishedName
Write-host “Object Cat. = “  $userEntry.objectCategory
Write-host “servicePrincipalNames”        $i=1

foreach($SPN in $userEntry.servicePrincipalName)
{
  Write-host “SPN(“ $i “)   =      “ $SPN       $i+=1
  }
Write-host “”

}

(run this powershell on a DC with admin rights)