PRB: DCOM Does Not Work over Network Address Translation-Based Firewall (248809)


The information in this article applies to:

  • Microsoft COM, when used with:
    • the operating system: Microsoft Windows 2000
    • the operating system: Microsoft Windows NT 4.0
This article was previously published under Q248809

SYMPTOMS

When you try to make Distributed Component Object Model (DCOM) calls over a Network Address Translation (NAT)-based Firewall, you receive the error 0x800706BA (RPC_S_SERVER_UNAVAILABLE).

CAUSE

For DCOM to work, the client must be able to reach the server by its actual IP address. If you use firewalls that translate network addresses, the client cannot use the actual IP address to reach the server.

COM inserts the IP address of the server computer into the interface marshaling packets that are returned to the client. Instead of using the translated IP/header, Remote Procedure Call (RPC, or DCOM) uses the actual IP address to reach the server. Because the firewall prevents the client from directly accessing the server, the client receives the above-mentioned error message.

REFERENCES

For more information on using DCOM with firewalls, see the following Microsoft Web site:

http://www.microsoft.com/com/wpaper/dcomfw.asp

For additional information, click the article numbers below to view the articles in the Microsoft Knowledge Base:

154596 HOWTO: Configure RPC Dynamic Port Allocation to Work with Firewall

193230 PRB: Server.CreateObject Fails When Object Is Behind Firewall

249726 HOWTO: Search for COM and DCOM Knowledge Base Articles

Modification Type:MajorLast Reviewed:11/17/2003
Keywords:kbClient KbClientServer kbDCOM kbprb kbServer KB248809
©2003 Microsoft Corporation. All rights reserved.