Kerberos Authentication Requires SPNs for Multiple Worker Processes
can isolate Web sites that are in different worker processes and
running under different identities; however, unexpected IIS behavior
might occur if you use Integrated Windows authentication. Integrated
Windows authentication attempts to use Kerberos authentication, which
might not work, depending upon the identity of the worker process. To
use Kerberos authentication, a service must register its Service
Principal Name (SPN) in the account in the Microsoft Active Directory®
directory service under which the service is running. By default,
Active Directory registers the NetBIOS name or computer name and allows
the Network Service or LocalSystem user accounts to use Kerberos.
However, for Kerberos to work with the following configurations, you
must first register an SPN:
can use the Setspn.exe command-line tool to register an SPN on the
account under which the worker process is running. You must be a domain
administrator to set an SPN. The Setspn.exe tool is included in
Resource Kit Tools for Windows Server 2003, available on the Windows Server 2003 Deployment Kit companion CD, or on the Web at http://www.microsoft.com/reskit.
this behavior occurs when the application pool is running under a local
account, follow the steps in the "Workaround" section.
resolve this behavior when the application pool is running under a
domain user account, set up an HTTP SPN with the NetBIOS name and the
fully qualified domain name (FQDN) of the domain user account that the
application pool is running under. To do this, follow these steps on a
Important An SPN for a service can
only be associated with one account. Therefore, if you use this
suggested resolution, any other application pool that is running under
a different domain user account cannot be used with Integrated Windows
|1.||Install the Setspn.exe tool. To obtain the Microsoft Windows 2000 version of the tool, visit the following Microsoft Web site:
|2.||Start a command prompt, and then change to the directory where you installed Setspn.exe.|
|3.||At the command prompt, type the following commands. Press ENTER after each command:
setspn.exe -a http/IIS_computer's_NetBIOS_name DomainNameUserName
setspn.exe -a http/IIS_computer's_FQDN DomainNameUserName
Note UserName is the user account that the application pool is running under.
you set the SPN for the HTTP service to the domain user account that
the application pool is running under, you can successfully connect to
the Web site without being prompted for your user credentials.
work around this behavior if you have multiple application pools that
run under different domain user accounts, you must force IIS to use
NTLM as your authentication mechanism if you want to use Integrated
Windows authentication only. To do this, follow these steps on the
server that is running IIS:
|1.||Start a command prompt.|
and then change to the directory that contains the Adsutil.vbs file. By
default, this directory is C:InetpubAdminscripts.
|3.||Type the following command, and then press ENTER:
cscript adsutil.vbs set w3svc/NTAuthenticationProviders "NTLM"
|4.||To verify that the NtAuthenticationProviders metabase property is set to NTLM, type the following command, and then press ENTER:
cscript adsutil.vbs get w3svc/NTAuthenticationProviders
The following text should be returned:
NTAuthenticationProviders : (STRING) "NTLM"