Abstract: A method and a system for providing security to a network by at least identifying an unauthorized user who is attempting to gain access to a node on the network, and preferably by then actively blocking that unauthorized user from further activities. Detection is facilitated by the unauthorized user providing a “mark”, or specially crafted false data, which the unauthorized user gathers during the information collection stage performed before an attack. The mark is designed such that any attempt by the unauthorized user to use such false data results in the immediate identification of the unauthorized user as hostile, and indicates that an intrusion of the network is being attempted. Preferably, further access to the network is then blocked by diverting traffic from the unauthorized user to a secure zone, where the activities of the unauthorized user can be contained without damage to the network.