I see a problem with installing an NDIS LWF over a Windows 7 SP1 MAC bridge. The configuration is this:
1… Use a configuration with either two LAN adapters, or 1 LAN and 1 WLAN. Disconnect one of the adapters but make sure the connected adapter has a connection to a DHCP server.
2… Create a MAC bridge using these two adapters. Once created, the MAC bridge should have an IP address from the DHCP server (i.e., a non-link-local address).
3… Install the LWF built from the WDK’s NDIS filter sample. You should see that the MAC bridge now loses it’s IP configuration and reverts to a link-local address.
4… Uninstall the LWF and the MAC bridge should regain an IP address from the DHCP server.
I have tried steps 3-4 repeatedly on Windows 7 Ultimate SP1 x86. Occasionally, the MAC bridge does get an IP address but most of the time it doesn’t and reverts to a link-local address. If I debug the LWF through WinDbg, I see that the binding to the MAC bridge miniport is in a media disconnected state even though the icon in Network Connections shows the bridge as connected.
Once in this state, I can clear it by rebooting the system. When the system comes up, the bridge gets an IP address from the server and the LWF shows the MAC bridge miniport binding as media connected.
I have tried this same test on Windows 8 x32, and cannot reproduce it. Every time I install the LWF, the bridge retains its IP address and configuration.
So, my guess is that this is a problem with the Windows 7 MAC bridge miniport driver. However, is there any workaround for this that I can add to my LWF?