The internet cafe across the street from La Ciutat operates a wireless network with no encryption. Originally, it was wide open, and there was no billing for time used as there is if you go in and log onto one of the computers. To fix this, NetKiosk added an authentication system like those used by Georgia Tech and UPC FIB (the local equivalent of the College of Computing). In general, systems like this are much more secure in terms of restricting access, since you cannot get online unless you first log in.
This of course does not keep others from reading the messages you sent. A few people who had used the wireless system before the authentication was added noticed they could close the login screen instead of logging in, and were still able to browse just fine. It turns out the authentication system at NetKiosk has a hole, and still allows the original users access, since their MAC addresses were already given access, since timing used to be done manually. Other users can now clone the MAC addresses of these cards to also have free access, just not at the same time.
Upon further investigation, it also seems there is an error in the accouting of registered users. All registered users are able to connect, then disconnect, and the connection continues to work without affecting the amount of credit they have left