Microsoft KB Archive/233387

= RAS Clients Cannot Access LAN When IP Forwarding is Disabled =

Article ID: 233387

Article Last Modified on 11/1/2006

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APPLIES TO


 * Microsoft Windows NT Server 4.0 Standard Edition
 * Microsoft Windows NT Workstation 4.0 Developer Edition

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This article was previously published under Q233387



SUMMARY
When 'IP Forwarding' is disabled, Windows NT 4.0 no longer performs static routing based on the routes defined in its route table. As a result, in addition to not routing IP packets between its distinct local subnets, Windows NT 4.0 does not route IP packets from its RAS clients to its LAN, even if these RAS clients use IP addresses that belong to the same subnet as that of the LAN by design.



MORE INFORMATION
'IP Forwarding' can be enabled or disabled in Control Panel Network, Protocols tab, properties of TCP/IP, Routing tab.

With 'IP Forwarding' enabled, Windows NT 4.0 routes IP packets according to the routes defined in its route table. This enables a Windows NT 4.0 RAS server to route IP traffic to and from a RAS client using the host route whose destination is the RAS client's specific IP address and whose gateway is the RAS server's NdisWAN Adapter.

When IP forwarding is disabled, a Windows NT 4.0 RAS server no longer routes IP traffic according to its route table and so RAS clients, regardless of their IP address, are NOT able to send or receive IP traffic to or from the RAS server's LAN. In this respect, disabling 'IP Forwarding' restricts a RAS client's access to its RAS server, even if the RAS service's TCP/IP configuration is set to permit its RAS clients 'Access to Entire Network.'

Keywords: kbinfo KB233387

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