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Q241812: DUN Clients Cannot Obtain Access to the LAN

Article: Q241812
Product(s): Microsoft Windows NT
Version(s): winnt:4.0
Operating System(s): 
Keyword(s): kbnetwork
Last Modified: 08-AUG-2001

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The information in this article applies to:

- Microsoft Windows NT Server version 4.0 
- Microsoft Routing and Remote Access Service Update for Windows NT Server version 4.0 
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SUMMARY
=======

When you install Microsoft Proxy 2.0 on your Microsoft Windows NT 4.0-based
computer, the common recommendation is to disable Internet Protocol (IP)
forwarding. This is usually recommended to prevent the computer from routing
packets to the internal network. This article describes the behavior of remote
access Dial-Up Networking (DUN) clients based on whether this setting is enabled
or disabled.

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

When your Windows NT 4.0-based computer is running Remote Access Service (RAS)
or Routing and Remote Access Service (RRAS) in addition to Microsoft Proxy 2.0,
the IP forwarding setting controls the following behavior for remote access DUN
clients:

IP Forwarding Is Disabled
-------------------------

Remote access DUN clients are able to obtain access to the Proxy 2.0 RAS (or
RRAS) Proxy 2.0 server only.

IP Forwarding Is Enabled
------------------------

Remote access DUN clients are able to obtain access to the Proxy 2.0 RAS (or
RRAS) Proxy 2.0 server, and to resources on the local area network (beyond the
proxy).

NOTE: Proxy 2.0 Autodial is not affected by the IP forwarding setting, because
the DUN connections are outgoing.

To configure IP forwarding on your Windows NT 4.0-based computer:

1. Click Start, point to Settings, click Control Panel, and then double-click
  Network.

2. Click the Protocols tab, and then double-click TCP/IP Protocol.

3. Click the Routing tab, and then click to select or click to clear the Enable
  IP Forwarding check box.

Additional query words:

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Keywords          : kbnetwork 
Technology        : kbWinNTsearch kbWinNT400search kbWinNTSsearch kbWinNTS400search kbWinNTS400 kbAudDeveloper kbRRASNTSearch kbRRASNT400
Version           : winnt:4.0
Issue type        : kbinfo

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