RPC calls to the NNTP Service fail on a Windows Server 2003 SP1-based computer, and you notice the following error information: "System.Runtime.InteropServices.COMException (0x80004005)"

Consider the following scenario:

• On a Microsoft Windows Server 2003 Service Pack 1 (SP1)-based computer, you are running the NNTP Service.
• To synchronize Network News Transport Protocol (NNTP) information among multiple servers, you make programmatic remote procedure calls (RPCs) to the NNTP Service and to the Distributed Transaction Coordinator service.

In this scenario, you experience intermittent RPC failures in your program. Additionally, when you troubleshoot your program, you notice error information that is similar to the following:

This problem occurs because of a code problem in the Nntpapi.dll file. This file contains an incorrect Service Principal Name (SPN).

The Nntpapi.dll file that is included in Windows Server 2003 SP1 adds an additional security control over RPC calls. As client-side code, the Nntpapi.dll process calls the RpcBindingSetAuthInfoEx function when it authenticates the NNTP Service from the client. However, the Nntpapi.dll process passes an incorrect SPN in this function. Specifically, the Nntpapi.dll process passes an SPN of "NNTPSVC." Therefore, the following behavior occurs:

• When a client makes an RPC connection to the NNTP Service (NNTPSVC) and calls the RpcBindingSetAuthinfoW function, the Nntpapi.dll process passes an incorrect SPN. In this situation, the RPC call still works. However, because the SPN is invalid, the RPC runtime does not verify server authentication for the client.
• When the same client makes an RPC call to another server, the RPC runtime must verify whether the same context exists. If the second RPC call also passes an SPN, the RPC runtime performs a string comparison to determine whether this same context exists. In this situation, it is not important whether the SPN is valid. Both the first RPC call and the second RPC call work.
• If the client makes a third RPC connection, and if the client sets a SID in the RpcBidingSetAuthInfoW function, the RPC runtime compares the SID with the SPN to determine whether this context exists. If the SPN is invalid in this situation, verification fails. Therefore, this third RPC call fails.

Service pack information

To resolve this problem, obtain the latest service pack for Windows Server 2003. For more information, click the following article number to view the article in the Microsoft Knowledge Base:

Hotfix information

A supported hotfix is available from Microsoft. However, this hotfix is intended to correct only the problem that is described in this article. Apply this hotfix only to systems that are experiencing this specific problem. This hotfix might receive additional testing. Therefore, if you are not severely affected by this problem, we recommend that you wait for the next software update that contains this hotfix.

If the hotfix is available for download, there is a "Hotfix download available" section at the top of this Knowledge Base article. If this section does not appear, contact Microsoft Customer Service and Support to obtain the hotfix.

Note If additional issues occur or if any troubleshooting is required, you might have to create a separate service request. The usual support costs will apply to additional support questions and issues that do not qualify for this specific hotfix. For a complete list of Microsoft Customer Service and Support telephone numbers or to create a separate service request, visit the following Microsoft Web site: Note The "Hotfix download available" form displays the languages for which the hotfix is available. If you do not see your language, it is because a hotfix is not available for that language.

Prerequisites

No prerequisites are required to apply this hotfix.

Restart requirement

You do not have to restart the computer after you apply this hotfix.

Hotfix replacement information

This hotfix does not replace any other hotfixes.

File information

The English version of this hotfix has the file attributes (or later file attributes) that are listed in the following table. The dates and times for these files are listed in Coordinated Universal Time (UTC). When you view the file information, it is converted to local time. To find the difference between UTC and local time, use the Time Zone tab in the Date and Time tool in Control Panel.

Microsoft Windows Server 2003, x86-based 32-bit versions

Microsoft Windows Server 2003, x64-based 64-bit versions

Microsoft Windows Server 2003, IA64-based 64-bit versions

Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section. This problem was first corrected in Windows Server 2003 Service Pack 2.

For more information, click the following article number to view the article in the Microsoft Knowledge Base:For more information, click the following article number to view the article in the Microsoft Knowledge Base: