Attach NDIS LWF driver to a Virtual Network Adapter? (Kerio)

Question

We have an NDIS LWF driver, and it seems like it cannot get attached to Virtual Network Adapters, for example the one that Kerio Control VPN client creates (Kerio Virtual Network). When i try to install the NDIS LWF in the network adapter manually by giving it our INF file (Install -> service -> Have disk), the driver doesn't appear in the network service list.

Then i found out that i if add nolower in the FilterMediaTypes in the inf file, it does appear in the network service list, but even then, when i click on OK, it doesn't get added to the list of items and doesn't get attached.

My question is, How can i attach to this Kerio Virtual Network Adapter in order to monitor its packets?

Answer 1

LWFs cannot bind to a network interface that has HKR, Ndi\Interfaces,LowerRange,,nolower in its INF. Generally speaking, the network interface ought to have at least one real LowerRange, and it's reasonable to ask the vendor to add one. For whatever it's worth, we (the Windows OS team) originally shipped the Bluetooth PAN adapter with nolower, and then later realized we needed to update it to have something there, so LWFs could bind to it. Perhaps that anecdote helps motivate this vendor to update their INF.

If the NDIS datapath uses a 14 byte Ethernet-like header and is roughly compatible with Ethernet's ideas of unicast & multicast, then ethernet is the correct thing to put in LowerRange. See the docs for more details.

It's not supported to try and add the nolower token to your LWF driver INF's FilterMediaTypes; you can't reasonably expect to bind to any unknown type of interface. What if the next network adapter indicates packets in some yet-to-be-invented framing layer — how could your LWF possibly make sense of those packets? For that reason, nolower is not a binding interface; it's a special token that means "the empty list".

LWFs also cannot bind to CoNDIS network adapters. This is simply because the LWF programming model has never been extended to cover all the additional signaling for connection management.

I am not personally familiar with the "Kerio" network interface — I don't know if it has nolower in its INF or whether it's CoNDIS (!ndiskd would tell you this). If it's the former, you should ask that vendor to update their INF.