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DCOM port range configuration problems

Article ID: 217351 - View products that this article applies to.

This article was previously published under Q217351

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SYMPTOMS

You may notice the following symptoms:

World Wide Web Publishing fails to start, and the following event appears in the Event log:
Event ID: 7023
Source: Service Control Manager
Description: The World Wide Web Publishing Service terminated with the following error: The endpoint cannot be created.
If you try to stop services such as W3SVC, MSFTPSVC, SMTPSVC, SS LDAP, or SS Messaging, the attempt fails with the following error message:
Error 1721: Not enough resources are available to complete this operation
Distributed Component Object Model (DCOM) clients that try to connect to the DCOM server fail with the following error message:
RPC_S_SERVER_UNAVAILABLE (0x800706ba) - The RPC server is unavailable

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CAUSE

This problem occurs because of improper configuration of the port range settings in the

HKEY_LOCAL_MACHINE\Software\Microsoft\Rpc\Internet

registry key or because the port restrictions for a protocol are configured through the DCOMCNFG protocol property page.

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Important This section, method, or task contains steps that tell you how to modify the registry. However, serious problems might occur if you modify the registry incorrectly. Therefore, make sure that you follow these steps carefully. For added protection, back up the registry before you modify it. Then, you can restore the registry if a problem occurs. For more information about how to back up and restore the registry, click the following article number to view the article in the Microsoft Knowledge Base:

322756

(http://support.microsoft.com/kb/322756/ )

How to back up and restore the registry in Windows

To resolve this problem, use one of the following methods:

If you do not want to configure DCOM to use a range of ports, delete the registry key, and then restart your computer.
If you want to configure DCOM on your computer to use a range of ports, use the
HKEY_LOCAL_MACHINE\Software\Microsoft\Rpc\Internet
registry key to configure the range of ports, and follow the instructions in the following white paper:
Using Distributed COM with Firewalls
http://msdn.microsoft.com/en-us/library/ms809327.aspx
(http://msdn.microsoft.com/en-us/library/ms809327.aspx)
If you used the DCOMCNFG utility to configure port restrictions, you may be encountering a known DCOMCNFG bug. For more information, click the following article number to view the article in the Microsoft Knowledge Base:
201911
(http://support.microsoft.com/kb/201911/ )
DCOMCNFG writes ports named value in incorrect format
Rather than use the DCOMCNFG utility, use Regedt32.exe to configure the port restrictions as described in the white paper.

The number of ports to be opened depends on the number of DCOM applications and other services that are running on the computer. For example, each instance of a DCOM application process uses one port; Microsoft Internet Information Server (IIS) uses a minimum of five ports.

In addition, it is important to determine the range of ports to be opened. For instance, Microsoft SQL Server uses port 1433 for incoming requests and ports 1024-5000 for outgoing calls. Considering these factors, it is recommended that you open a minimum of 100 ports and use a port range that is above 5000. For example, configure DCOM to use port range 5000-5100.

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MORE INFORMATION

Configuring the computer to use a range of ports can break other applications on the system. On systems that are running Microsoft Windows NT 4.0 Service Pack 4 and later, the best alternative is to configure the DCOM application to use the static endpoint by using the AppId key.

To configure the DCOM application to use a static port by using TCP/IP as the DCOM protocol, follow these steps:

On the Client Computer:

From the Start menu, click Run, type DCOMCNFG, and then click OK.
On the Default Protocols tab, move Connection-oriented TCP/IP protocol to the top of the list, and restart the computer.

On the Server Computer:

From the Start menu, click Run, type DCOMCNFG, and then click OK.
On Default Protocols tab, move Connection-oriented TCP/IP protocol to the top of the list.
Using tools such as OLEVIEW, find your application's AppId globally unique identifier (GUID).
Start the Registry Editor (Regedt32.exe).
Locate the following key in the registry:
HKEY_CLASSES_ROOT\AppId\{AppId GUID}
On the Edit menu, click Add Value, and then add the following registry value:
Value Name: Endpoints
Data Type: REG_MULTI_SZ
Value: ncacn_ip_tcp,0,<port number>
where <port number> is the static port that you want to use.
Quit the Registry Editor.
Restart the computer.

Note that your application may not pick up the static endpoint from the registry if the mapping for the .exe name to the AppId does not exist in the registry.

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