SETSPN.exe (Windows 2003+ or via AD DS)

Read, modify, or delete the Service Principal Names (SPN) for an Active Directory service account.

Syntax
      SETSPN [modifiers switch] [accountname]

Key
   accountname  The name or domain\name of the target computer or user account

   Edit Mode Switches:
   -R = reset HOST ServicePrincipalName
        Usage:  setspn -R accountname

   -A = add arbitrary SPN  
        Usage:  setspn -A SPN accountname

   -S = add arbitrary SPN after verifying no duplicates exist
        Usage:  setspn -S SPN accountname

   -D = delete arbitrary SPN
        Usage:  setspn -D SPN accountname

   -L = list SPNs registered to target account
        Usage:  setspn [-L] accountname   

  Edit Mode Modifiers:
   -C = accountname is a computer account
   -U = accountname is a user account
   
        Note: -C and -U are exclusive.  If neither is specified, setspn
        will interpret accountname as a computer name if such a computer
        exists, and a user name if it does not.

  Query Mode Switches:
   -Q = query for existence of SPN
        Usage:  setspn -Q SPN

   -X = search for duplicate SPNs
        Usage:  setspn -X

searching for duplicates, especially forestwide, can take a long period of time and a large amount of memory.
-Q will execute on each target domain/forest.
-X will return duplicates that exist across all targets. SPNs are not required to be unique across forests, but duplicates can cause authentication issues when authenticating cross-forest.

  Query Mode Modifiers:
   -P = suppress progress to the console, use when redirecting output to a file or 
        in an unattended script. There will be no output until the command is complete.

   -F = perform queries at the forest, rather than domain level

   -T = perform query on the specified domain or forest (when -F is also used)
        Usage:  setspn -T domain (switches and other parameters)
        "" or * can be used to indicate the current domain or forest.

Note: these modifiers can be used with the -S switch in order to specify where the check for duplicates should be performed before adding the SPN. Note: -T can be specified multiple times.

SPNs are set up automatically when a computer joins a domain (and when some services are installed). Some services and applications (e.g. SharePoint) require manual modification of a service account's SPN information to authenticate correctly.

If the computer name or Alias is changed, the SPNs for installed services must be changed to match.

Use Setspn -S in preference to Setspn -A, the -S will verify that there are no duplicate SPNs. However, on Windows Server 2003, the -S switch is only available if you update to the SetSPN version from Q970536. Alternatively verify manually that there are no duplicates by running Setspn -L

setspn must be run from an elevated command prompt.

Administrators with only delegated authority (non domain administrators) will require the Validated write to service principle name permission to configure service principal names (SPNs).

Duplicate SPNs will cause Kerberos to fail and fall back to NTLM, run setspn -x periodically to check for this.

SPN Format

When you manipulate SPNs with setspn, the SPN must be entered in the correct format. The format of an SPN is serviceclass/host:port/servicename, in which each item represents a name or value.
Unless the service name and port are non standard, you do not have to enter them.

For example, the default SPNs for a server named Server64 that is providing remote desktop (RDP) services (TERMSRV) over the default port (TCP 3389) register the following two SPNs in its own Active Directory computer object:
TERMSRV/Server64
TERMSRV/Server64.ss64.com

Examples

View a list of the SPNs that the computer server64 has registered with Active Directory from a command prompt:

setspn –l server64

View a list of the SPNs that the local computer has registered with Active Directory from a command prompt:

setspn –l hostname

Reset the SPNs for the computer server64 back to the default:

setspn -r server64

Add an SPN for LDAP to an AD domain controller with the host name dc1.ss64.com:

setspn -s ldap/dc1.ss64.com dc1

Delete the SPN for LDAP from an AD domain controller with the host name dc1.ss64.com:

setspn -d ldap/dc1.ss64.com dc1

Create an alias name for a server:

Create a CNAME record (not a normal Host(A) record.) in DNS:

Set the DisableStrictNameChecking key in the registry:
HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\LanmanServer\Parameters
DisableStrictNameChecking
Data type: REG_DWORD
Set Value: 1

On the server create SPN's for the flat name and the fully qualified name of the cname alias:
setspn -S host/your_ALIAS_name ServerName
setspn -S host/your_ALIAS_name.domain.com ServerName

Then reboot the Host.

“I have the world's worst taste in men, so now I simply have wonderful relationships of the friend kind, but trying to settle down with somebody? No, no, no, no, no, no, no. I'm beyond that” ~ Harvey Fierstein

Related commands:

RepAdmin - Diagnose Active Directory replication problems between domain controllers.
DcDiag - Analyze the state of domain controllers and report any problems.
DsMgt - Manage password operations over unsecured connections, AD Lightweight Directory Services application partitions, flexible single master operations (FSMO), and clean up AD metadata.
TechNet - Troubleshooting SPN Issues


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