Ok, we could use randomly chosen live media for the control computer in the middle instead of changing the hardware several times a day, but it's more risky. Anyway, instead of my USB stick I guess you're right, the manually disconnected and connected ethernet cable is the most save way, but really no wlan, we are talking about a cable connection and we insert and remove the cable after looking out of our windows, to ensure that there are no black helicopters in front of our houses.
