I'm trying to figure out what information about my infrastructure can leak through Wi-Fi.
I ran Kismet and was surprised to see that a few minutes later, Kismet displayed not only the MAC addresses of mobile devices connected to my Wi-Fi, but also MAC addresses of devices which don't use Wi-Fi, such as the Ethernet surveillance camera or a bunch of virtual machines hosted on the servers which have no Wi-Fi access. This, obviously, is not very pleasing, since I don't expect anyone parked outside the building for a few hours to get an exact picture of the infrastructure.
How does Kismet know about those devices? I'm quite sure virtual machines I've seen in the list don't broadcast anything, so what is happening here?
What do I do in order to prevent this sort of information from leaking to anyone ready to listen to it? Wi-Fi access points are on the same network (i.e. they are connected to the same switch as the servers, and use the same network parameters), which, as I imagine, is a really bad idea. Should I get a dedicated network for them (with a router in the middle), or are there alternatives?