Norse, a security start up, has been gathering astounding evidence of hackers taking control of Internet-connected appliances, everything from web cams, baby monitors and medical devices to climate-control systems. What the bad guys really want is the IP address of the device to use for credit card fraud. "We are seeing credit card transactions from baby monitors, DVRs, TVs, printers, medical devices, you name it," says Tommy Stiansen, Norse founder and chief technology officer. "It's coming from all types of industries and from homes." This is leading to the assembling of digital appliances into niche networks, called botnets, under the control of a single operator. Botnets have been the foundation of the cyber underground for more than a decade. Traditionally comprising infected personal and server computers, botnets are the engine that drives multibillion-dollar markets for spam, phishing, account hijacking, identity theft, and denial-of-service attacks. Take a look at some ideas on protecting yourself from botnets.