The annual Defcon hacking meetup produces its share of unique creations. You know you're in for something special when even your entrance badge is an adventure. Defcon 20 might be winding to a close, but about 650 guests may just have the fondest memory of all: access to a private, ad hoc GSM carrier from Ninja Networks. While the collective's Ninja Tel is really an invitation to a party at the Rio Hotel, where the lone cell site operates out of a va
