you without -- as you pick up a magazine to read it, you don't want the magazine to be reading you. >> reporter: recently the ftc weighed in calling for a do not track system like a do not call system but eckersley says the technology is already there to put this button on your browser but won't happen until congress creates a whole new set of rules. >> people don't understand what's out there about them personally linked to their online digital fingerprint. >> reporter: this man tsays it' using for customized political messaging and advertising but there's a danger they will be used with malicious intent. what if i'm at a wireless place like this and people are everywhere. can that guy right there be track snd. >> absolutely. he is being tracked right now. everything you do online, if you use a public website or any kind