A structural method used to control access. This function uses access control devices installed both inside and outside the door, so that authentication is required for access to the zone. In the case of card-based access control systems, if a person enters a zone following the person in front without swiping their card on the reader, the door does not open when the person attempts to leave the zone, and subsequently an anti-passback event occurs. Anti-passback is categorized into hard APB and soft APB. If the anti-passback is violated, the anti-passback event is created immediately and hard APB does not permit access to the user while soft APB still permits access to the user.