An access control system (200) enables a computer network (1) to prevent execution of computer code that may contain computer viruses. An access control console (201) generates an access control message (260) including control parameters such as a time limit (255). Said time limit (255) is disseminated...http://www.google.com.hk/patents/US7483993?utm_source=gb-gplus-share專利 US7483993 - Temporal access control for computer virus prevention
