IP based cameras are the future. They work by turning images and audio into data then transmitting this data over a network or Internet connection. The ultimate benefit of this over analogue CCTV systems is greater flexibility, better performance and easier installation.
IP CCTV systems do not require local recording, they can transmit their images across Local Networks, the Internet and Wide Area Networks to a central location, where they can be recorded, viewed and managed.
Credentials can be passed around, thus subverting the access control list. To prevent this, two-factor authentication can be used. In a two factor transaction, the presented credential and a second factor are needed for access to be granted; another factor can be a PIN, a second credential, operator intervention, or a biometric input.