DCOM port range configuration problems (217351)


The information in this article applies to:

  • Microsoft Windows NT Server 4.0
  • Microsoft Windows NT Workstation 4.0
This article was previously published under Q217351
Important This article contains information about how to modify the registry. Make sure to back up the registry before you modify it. Make sure that you know how to restore the registry if a problem occurs. For more information about how to back up, restore, and modify the registry, click the following article number to view the article in the Microsoft Knowledge Base:

256986 Description of the Microsoft Windows registry

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

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.

RESOLUTION

Warning Serious problems might occur if you modify the registry incorrectly by using Registry Editor or by using another method. These problems might require that you reinstall your operating system. Microsoft cannot guarantee that these problems can be solved. Modify the registry at your own risk.
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://www.microsoft.com/com/wpaper/dcomfw.asp

    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 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.

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:
  1. From the Start menu, click Run, type DCOMCNFG, and then click OK.
  2. 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:
  1. From the Start menu, click Run, type DCOMCNFG, and then click OK.
  2. On Default Protocols tab, move Connection-oriented TCP/IP protocol to the top of the list.
  3. Using tools such as OLEVIEW, find your application's AppId globally unique identifier (GUID).
  4. Start the Registry Editor (Regedt32.exe).
  5. Locate the following key in the registry:

    HKEY_CLASSES_ROOT\AppId\{AppId GUID}

  6. 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.
  7. Quit the Registry Editor.
  8. 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.

REFERENCES

For more information regarding the mapping for the .exe name, click the following article number to view the article in the Microsoft Knowledge Base:

216051 FIX: DCOMCNFG NT 4.0 SP4 Does Not Write .exe Name under HKCR\APPID

Modification Type:MajorLast Reviewed:8/16/2005
Keywords:kbnofix kbprb KB217351
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