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Mr. O’Connor, 27, bought some plastic boxes and stuffed them with a $25, credit-card size Raspberry Pi Model A computer and a few over-the-counter sensors, including Wi-Fi adapters. He connected each of those boxes to a command and control system, and he built a data visualization system to monitor what the sensors picked up: all the wireless traffic emitted by every nearby wireless device, including smartphones. Each box cost $57. He produced 10 of them, and then he turned them on – to spy on himself. He could pick up the Web sites he browsed when he connected to a public Wi-Fi – say at a cafe – and he scooped up the unique identifier connected to his phone and iPad. Gobs of information traveled over the Internet in the clear, meaning they were entirely unencrypted and simple to scoop up. (via A Cheap Spying Tool With a High Creepy Factor - NYTimes.com)