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We are implementing a system where our clients are Windows XP and our server is Windows Server 2008 R2. Ours clients use DCOM to connect COM+ components in our Windows 2008 Server.

It works fine when the user defined in our COM+ package is a local user. However we need acces to network shares in the COM+ component, so we need to use a AD user in our COM+ package. But then we have Kerberos error : KDC_ERR_S_PRINCIPAL_UNKNOWN

So I read that it was a missing SPN. I used network monitor to trace the name of that SPN. I got a SNAME in the following format : user@domain (see screen)

If I run the following command setspn -s user@domain domain\user

it says the name is invalid. It expect a name in the following format : service\host.

Anyone could point me what I am doing wrong to debug this ?

Also please note that I had a preauthentication issue in my event log before I had this issue. I desactivated the preauthentification for the user in our AD.


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up vote 2 down vote accepted

Instead of using "user@domain" you should use the syntax as documented here.

I found the following commands ("-A" parameter is changed to "-s") in this article.

setspn -s DCOMService/DCOMServer Domain\DCOMServiceAccount
setspn -s DCOMService/DCOMServerFQDN Domain\DCOMServiceAccount
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Asked a domain admin to run the command. Will keep you informed if it works. Thanks ! – Simon May 9 '13 at 17:21
It works !! Thanks !! – Simon May 9 '13 at 18:17

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