Microsoft KB Archive/224460

= Err Msg: Error Connecting to  The RPC Service Is Not Available =

Article ID: 224460

Article Last Modified on 6/23/2005

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APPLIES TO


 * Microsoft Internet Information Server 4.0

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This article was previously published under Q224460



We strongly recommend that all users upgrade to Microsoft Internet Information Services (IIS) version 6.0 running on Microsoft Windows Server 2003. IIS 6.0 significantly increases Web infrastructure security. For more information about IIS security-related topics, visit the following Microsoft Web site:

http://www.microsoft.com/technet/security/prodtech/IIS.mspx



IMPORTANT: This article contains information about modifying the registry. Before you modify the registry, make sure to back it up and make sure that you understand how to restore the registry if a problem occurs. For information about how to back up, restore, and edit the registry, click the following article number to view the article in the Microsoft Knowledge Base:

256986 Description of the Microsoft Windows Registry



SYMPTOMS
When you attempt to remotely administer a multihomed IIS 4.0 computer from the Microsoft Management Console (MMC) on a local computer, the following error messages may occur:

Error connecting to The RPC service is not available

When you click OK, you may see a few additional errors similar to the following:

Unable to administer IIS "unable to connect to target machine"



CAUSE
This problem only occurs when you are trying to remotely administer a multihomed IIS 4.0 computer from the MMC on a local computer. The MMC uses the default DCOM protocol for remote communications. By default, DCOM uses the ncadg_ip_udp DCOM protocol for connections instead of ncacn_ip_tcp. Due to a problem with the ncadg_ip_udp DCOM protocol in Windows NT Service Pack 3, if the destination IIS computer is multihomed, ncadg_ip_udp causes the binding IP address to become corrupted.



RESOLUTION
To resolve this problem, obtain the latest service pack for Windows NT version 4.0. For additional information, see the following article or articles in the Microsoft Knowledge Base:

152734 How to Obtain the Latest Windows NT 4.0 Service Pack



WORKAROUND
If you have not yet implemented Windows NT Service Pack 4 in your environment, you can edit the registry to change the DCOM protocols that are used.

WARNING: If you use Registry Editor incorrectly, you may cause serious problems that may require you to reinstall your operating system. Microsoft cannot guarantee that you can solve problems that result from using Registry Editor incorrectly. Use Registry Editor at your own risk.

Follow these steps exactly on the multihomed remote Web server:  Back up the following registry key using Regedt32.exe (not Regedit.exe):

HKEY_Local_Machine\Software\Microsoft\RPC

To do this, highlight the RPC key and choose Registry, and the choose Save Key.

In the RPC key, edit the DCOM Protocols setting by double-clicking on it. Change the values to reflect a different order by removing the ncadg_ip_udp protocol and moving ncacn_ip_tcp to the top of the list. Here is what it will look like before and after the change:

Before

ncadg_ip_udp

ncadg_ipx

ncacn_ip_tcp

ncacn_spx

ncacn_nb_nb

ncacn_nb_ipx

Remove ncadg_ip_udp and move ncacn_ip_tcp to the top of the list.

After

ncacn_ip_tcp

ncadg_ipx

ncacn_spx

ncacn_nb_nb

ncacn_nb_ipx

After the changes are made, close Registry Editor and restart the computer. In the RPC key, edit the DCOM Protocols setting by double-clicking on it. Change the values to reflect a different order by removing the ncadg_ip_udp protocol and moving ncacn_ip_tcp to the top of the list. Here is what it will look like before and after the change:

Before

ncadg_ip_udp

ncadg_ipx

ncacn_ip_tcp

ncacn_spx

ncacn_nb_nb

ncacn_nb_ipx

Remove ncadg_ip_udp and move ncacn_ip_tcp to the top of the list.

After

ncacn_ip_tcp

ncadg_ipx

ncacn_spx

ncacn_nb_nb

ncacn_nb_ipx

After the changes are made, close Registry Editor and restart the computer. After the changes are made, close Registry Editor and restart the computer.

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STATUS
Microsoft has confirmed this to be a problem in Windows NT version 4.0. This problem was first corrected in Windows NT 4.0 Service Pack 4.

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MORE INFORMATION
For additional information about network connection delays, click the article number below to view the article in the Microsoft Knowledge Base:

288886 PRB: Delayed DCOM Activation on Multihomed Computers

Below is an example of how the binding fails.

Note: Binding Vector[4] has the incorrect IP addresses in the binding handle. In this example, it combines both IP addresses from both NICs, thus corrupting the IP address format, and the connection fails.

Display STRING representation for each binding handle in Binding Vector

Binding Handle Count: 7

Binding Vector[0]: ncacn_np:\\\\ServerName[\\pipe\\000000B4.001]

Binding Vector[1]: ncalrpc:ServerName[WMSG000000B4.00000001]

Binding Vector[2]: ncacn_ip_tcp:157.61.239.61[1038]

Binding Vector[3]: ncacn_ip_tcp:157.61.239.5[1038]

Binding Vector[4]: ncadg_ip_udp:157.61.239.61157.61.239.5[1039]

Binding Vector[5]: ncadg_ip_udp:157.61.239.5[1039]

Binding Vector[6]: ncacn_nb_tcp:ServerName[106]

If you use network sniffers, such as Network Monitor, you can see the incorrect IP addresses as in the above example for Binding Vector[4].

Additional query words: mmc, ntop, iis, dcom, rpc, multi-homed, multi, homed sp hot fix qfe

Keywords: kbbug kbfix kbqfe KB224460

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