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Q183607: HOWTO: Configure DCOM for Visual Basic Using DCOMCNFG.EXE

Article: Q183607
Product(s): Microsoft Visual Basic for Windows
Version(s): 5.0
Operating System(s): 
Keyword(s): kbVBp kbVBp500 kbOSWin98 kbGrpDSVBDB kbDSupport
Last Modified: 11-JAN-2001

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The information in this article applies to:

- Microsoft Visual Basic Learning Edition for Windows, version 5.0 
- Microsoft Visual Basic Professional Edition for Windows, version 5.0 
- Microsoft Visual Basic Enterprise Edition for Windows, version 5.0 
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SUMMARY
=======

This article explains how to use the DCOM configuration utility DCOMCNFG.EXE to
configure DCOM for remote client/server applications created using Microsoft
Visual Basic 5.0.

Incorrectly setting up security for DCOM client/server applications will
typically result in the following errors:

  Run-time error '429'
  ActiveX component can't create object.

  -or-

  Run-time error '70'
  Permission denied.

This article does not discuss the settings required to enable client access
through firewalls. Please contact Microsoft Technical Support to obtain
assistance regarding firewalls, proxy servers, or domain controllers.

MORE INFORMATION
================

The following settings will enable Windows NT or Windows 2000 to communicate
with an NT or Windows client and back (assuming that there are no firewalls or
proxy servers involved).

To configure your Visual Basic DCOM "Server" on an NT or Windows 2000machine,
follow these steps: (Note that DCOMCNFG will only show servers that are EXEs. It
will not show DLL servers.)

1. Run DCOMCNFG.EXE.

2. From the Applications tab, select the DCOM Server application (which will be
  represented by its ProgID - a friendly name, such as "Your DCOM Server") or
  by its CLSID (a GUID - Globally Unique Identifier) such as
  {5BD7512F-3F2B-11D0-B4D2-02E0C911A7B1}).

3. Double-click the Server application or click the Properties button to view
  the properties of the server application.

4. Select the Security Tab.

5. Make the following changes:

  IMPORTANT: The following changes will allow anyone at all to launch the
  server. These settings are just for getting the servers up and running in
  development mode for debugging purposes. They are not intended for specific
  DCOM security on a target platform distribution.

  CUSTOM ACCESS PERMISSIONS:
    Everyone    -allow access
    System      -allow access
    Interactive -allow access

  CUSTOM LAUNCH PERMISSIONS:
    Everyone    -allow launch
    System      -allow launch
    Interactive -allow launch

6. Select the Identity Tab, and then select "The Interactive User."

7. Click OK, and then click OK again.

If your DCOM server is raising events to your clients or using client callbacks,
then you will also need to make the following changes to the default settings
for your NT or Windows 2000 'Server' machine:


On the NT or Windows 2000 SERVER machine:

1. Using DCOMCNFG.EXE, select the Default Properties Tab.

2. Set the Default Authentication Level to "None."

3. Set the Default Impersonation Level to "Identify."

NOTE: Make sure you test your DCOM application where the client and the server
are running under different user accounts.

If your application works at this point, then you should not need to make any
configuration settings on the client machines.

If your client is receiving events raised from the server or has enabled the
server to call it back, then the following steps might be necessary, depending
upon your specific network:

To configure your Visual Basic DCOM "Clients:"

On the NT or Windows CLIENT machines:

1. Using DCOMCNFG, select the Default Properties Tab.

2. Set the Default Authentication Level to "None."

3. Set the Default Impersonation Level to "Impersonate."

On the WIN95 CLIENT machines (if receiving events):

1. Using DCOMCNFG.EXE, select the Default Security Tab.

2. Click Edit Default.

3. Grant Access to "The World" user.

Modifying and setting security settings should be done with caution and
awareness. Before modifying security settings, be sure that you understand the
security implications involved. The above client settings are only necessary in
certain network situations and can be added via setup code to the clients
registry. For more information about writing such code see the References
section later in this article.

NOTE: DCOM registry keys are intended for Legacy software and not for Proprietary
software or programming convenience.

REFERENCES
==========

For more detailed information regarding DCOM security settings, please see the
following articles in the Microsoft Knowledge Base:

  Q176799 : INFO: Using DCOM Config (DCOMCNFG.EXE) on Windows NT

  Q182248 : HOWTO:: Use DCOM Config (DCOMCNFG.EXE) on Windows 95

For more information regarding using WIN95 as a DCOM server, please see the
following article in the Microsoft Knowledge Base:

  Q165101 : HOWTO: Use Windows as a DCOM Server

Visual Basic 5.0 can use remote events callbacks to enable two-way communication
between DCOM clients and a DCOM server application.

For more information regarding using remote events or callbacks with DCOM and
Visual Basic 5.0, please see the following article in the Microsoft Knowledge
Base:

  Q175510 : FILE: VB5DCOM.EXE: Using Callbacks and WithEvents with DCOM

(c) Microsoft Corporation 1998, All Rights Reserved.
Contributions by Randy Russell, Microsoft Corporation

Additional query words: 429 70

======================================================================
Keywords          : kbVBp kbVBp500 kbOSWin98 kbGrpDSVBDB kbDSupport 
Technology        : kbVBSearch kbAudDeveloper kbZNotKeyword6 kbZNotKeyword2 kbVB500Search kbVBA500 kbVB500
Version           : :5.0
Issue type        : kbhowto

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