wdkndisfilter-driver

Windows NDIS filter driver

I am writing a NDIS filter driver for windows. When I examine NBL flags, say NDIS_NBL_FLAGS_IS_IPV4,it doesn't seem to have set, nor does any other flags of NblFlags field? Which driver in the stack sets these values?

Solution

  • These flags are not guaranteed to be set all the time in all situations. The flags are only needed when running over a native mobile broadband stack (because there is no MAC layer & EtherType to look at).

    If you are writing a generic LWF that needs to work in a variety of configurations, you can't rely on this flag, and you'll have to look at the packet payload itself to determine the packet type.