Microsoft KB Archive/813542

= Change in how self-directed loopback packets are processed for Windows XP =

Article ID: 813542

Article Last Modified on 12/19/2003

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APPLIES TO


 * Microsoft Windows XP Driver Development Kit

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SYMPTOMS
If a network driver interface specification (NDIS) protocol driver sends a packet down the networking stack that is self-directed (that is, the media access control [MAC] destination address is directed at itself), the behavior of other protocol drivers varies among versions of Microsoft Windows.

The way that self-directed loopback packets are processed varies as follows:
 * Microsoft Windows NT 4.0 and Microsoft Windows 2000

Other protocol drivers that are listening for directed packets (NDIS_PACKET_TYPE_DIRECTED) receive these packets.


 * Microsoft Windows XP

By default, these self-directed loopback packets are no longer looped back to other protocol drivers.



CAUSE
This change in Windows XP was made to improve general system security and stability because there is almost no justification for giving a packet that is sent by one protocol driver to another protocol driver.



RESOLUTION
To receive these packets, other protocol drivers must follow these steps:
 * 1) Specify either NDIS_PACKET_TYPE_PROMISCUOUS or NDIS_PACKET_TYPE_ALL_LOCAL.
 * 2) Filter unwanted packets, and then drop unwanted packets.



STATUS
This behavior is by design.

Keywords: kbndis kbprb KB813542

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