List all SPNs used in your Active Directory

There are a lot of hints & tips out there for troubleshooting SPNs, or Service Principal Names. Listing duplicate SPNs is fairly easy, just use setspn -X on your command-line and you’ll find out. But how do you find out which SPNs are used for which users and computers are used for this?

An SPN or Service Principal Name is a unique identity for a service, mapped with a specific account (mostly service account). Using an SPN, you can create multiple aliases for a service mapped with an Active Directory domain account.

SetSPN command-line

To set, list or delete the SPN, we use an in-built command line tool SETSPN (setspn.exe) provided by Microsoft. It Reads, modifies, and deletes the Service Principal Names (SPN) directory property for an Active Directory service account. You use SPNs to locate a target principal name for running a service. You can use setspn to view the current SPNs, reset the account’s default SPNs, and add or delete supplemental SPNs.

Setspn is a command-line tool that is built into Windows Server 2008. It is available if you have the Active Directory Domain Services (AD DS) server role installed.

Quite some scripts assume you’re looking for a specific SPN (HTTP/…), a specific user, or a specific computer. For example, you can use setspn to find (query) Service Principal Names (SPNs) linked to a certain computer:

setspn.exe -L <ServerName>Code language: PowerShell (powershell)

Or you can use setspn to find (query) SPNs linked to a certain user account:

setspn.exe -L <domain\user>Code language: PowerShell (powershell)

And now you need a general script to list all SPNs, for all users and all computers…

Use -SearchBase with Get-ADComputer for faster results

Retrieve SSH public key from Active Directory for SSH authentication

You delete arbitrary SPNs, or Service Principal Names, using the -D switch:

setspn.exe -D <spn> accountnameCode language: HTML, XML (xml)

List SPNs using Powershell

Nice to know fact, Service Principal Names (SPNs) are set as an attribute on the user or computer accounts. That makes it fairly ease to query for that attribute. And modern admins do PowerShell, right?

So… Save the following code into a new PowerShell .ps1 file and run it in your domain. It will query and list the Service Principal Names – SPNs.

# Source / credit:
# https://social.technet.microsoft.com/wiki/contents/articles/18996.active-directory-powershell-script-to-list-all-spns-used.aspx

cls
$search = New-Object DirectoryServices.DirectorySearcher([ADSI]"")
$search.filter = "(servicePrincipalName=*)"

## You can use this to filter for OU's:
## $results = $search.Findall() | ?{ $_.path -like '*OU=whatever,DC=whatever,DC=whatever*' }
$results = $search.Findall()

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 ""
}Code language: PowerShell (powershell)

Or use dsquery on your CMD.exe command-line:

dsquery * "ou=domain controllers,dc=yourdomain,dc=com" -filter "(&(objectcategory=computer)
(servicePrincipalName=*))" -attr distinguishedName servicePrincipalName > spns.txtCode language: PowerShell (powershell)

This is a valuable script and information reference for your own documentation.

Conclusion

In this post, I showed you multiple methods of listing Service Principal Names, or SPNs. Using appropriate tools like setspn.exe dsquery.exe or PowerShell, you can query your Active Directory for service accounts. For example duplicate SPNs or SPNs used for specific users and computers.

Frequently Asked Questions