physical and metaphorical sense, hacker attendees of this year's Chaos Communication Congress in Berlin are paying 10 euros to don RFID tags that track their movements all over the conference. What's different about this, in comparison to the RFID-based privacy invasion that these hackers usually eschew, is the visibility and open source nature of the system being used. "The idea was that most of this surveillance technology slowly faded into our lives, and we accepted them," says Milosch Meriac, one of the leaders of the project. The "CCC Sputnik" badges, as they're known, are tracked by 35 monitoring stations, which in turn export a public XML feed so that anyone who wants to can track the wearers around the expo. To generate an accurate position, the tags broadcast at five different power levels, with far-away receivers only receiving the highest powered signals, and close receivers receiving all five, the system can then triangulate the location of the wearer. The technology is par of the OpenBeacon surveillance suite that Meriac is prepping for release under the GPL and Creative Commons licenses.