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Windows 2000-Based Clients Cannot Use GSSAPI to Delegate to Kerberos Servers

Article ID: 274062 - View products that this article applies to.

This article was previously published under Q274062

SYMPTOMS

When you use Kerberos delegation and the program that is requesting the delegation uses Generic Security Services Application Programming Interface (GSSAPI) instead of Microsoft Security Support Provider Interface (SSPI) to request the session ticket, the GSSAPI delegate does not work.

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CAUSE

This problem can occur because there is a size computation problem in the Windows 2000 code which causes GSSAPI interoperability to be broken for MIT clients. Therefore, if a Kerberos delegation is made to an MIT Kerberos server, the delegation does not work.

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RESOLUTION

To resolve this problem, obtain the latest service pack for Windows 2000. For additional information, click the following article number to view the article in the Microsoft Knowledge Base:

260910

(http://support.microsoft.com/kb/260910/EN-US/ )

How to Obtain the Latest Windows 2000 Service Pack

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WORKAROUND

To work around this problem, apply the following patch to the MIT Kerberos source distribution:

*** accept_sec_context.c.orig   Thu Aug 31 12:27:45 2000
--- accept_sec_context.c        Thu Aug 31 12:28:21 2000
***************
*** 502,508 ****

           i = authdat->checksum->length - 24;

!          while(i>0) {

               TREAD_INT16(ptr, option_id, bigend);

--- 515,521 ----

           i = authdat->checksum->length - 24;

!          while(i>4/*0*/) {    /* Win2000 bug */ 

               TREAD_INT16(ptr, option_id, bigend);

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STATUS

Microsoft has confirmed that this is a problem in the Microsoft products that are listed at the beginning of this article. This problem was first corrected in Windows 2000 Service Pack 2.

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MORE INFORMATION

When you use Kerberos delegation, a service or program on one server can access the services or program on another server on behalf of the original user. This is accomplished by passing the user's Ticket Granting Ticket (TGT) to a Key Distribution Center (KDC) and requesting tickets from the server that is hosting the service or program.

For additional information about GSSAPI, click the article number below to view the article in the Microsoft Knowledge Base:

266080

(http://support.microsoft.com/kb/266080/EN-US/ )

Answers to Frequently Asked Kerberos Questions

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