These are scary. It all started one day with this guy, the origional Etherkiller, developed with a few misc parts to warn new users that the IT department is not to be messed with. You too can make one at home, connect the transmit pins of the RJ-45 to HOT on 110VAC and the recieve pins to Common. Modify to suit tase by varying pinout. This led to some general discussion that this particular device really is in a class of devices, now called the “killers”, which need to be made. Link.