Can the MAC address of a mobile device be easily determined?

This is somewhat of a general questi开发者_如何转开发on, is it realistic to assume that a router can resolve any mobile device's MAC address without being already connected via wifi or bluetooth?

If the device is broadcasting, or if it's connected to another access point, then capturing the wifi data would allow you to capture the device's MAC address. Routers aren't generally set up to listen in that way, and I don't think it would be simple to configure that kind of behavior.

In general, if a device isn't connected to a wireless router/access point, you aren't going to be able to capture its MAC.