in less than five minutes -- >> three androids, two iphones and ipad. >> reporter: users are logging in. >> when criminals do this they pretend to be famous coffee shop names, hotel names. >> reporter: there is nothing stopping us from going into a starbucks setting up free wi-fi that says, starbucks free wi-fi. chester didn't peek at who jumped on his open network, but someone with bad intentions could. something to think about if you are tempted to save money on data roaming charges by using free wi-fi. so here's what you can do -- use your cell phone data plan instead of free wifi. or might want to consider paying a small monthly fee for vpn, virtual private network, encrypts your data and allows you to access free wi-fi safely. linsey davis, abc news, new york. >> i never knew that people could create their own free wi-fi networks and lure you in to potentially scam you. >> do you use free wi-fi? >> i stay away from free wi-fi