Abstract: In view of the “Stuxnet” and “Snowden” events, physical isolation exists the fact that network security perimeter has been broken,and its real security isolation effect arouse bitter controversy. This paper introduces three implementation technology approaches and two evolution processes of physical isolation and make safety analysis of each process. Some proposals related to physical isolation security problems are discussed; for instance, to establish global file exchange management system, to unify file exchange format, to establish electromagnetic compromising emanation protection requirements and to prevent memory information leakage. The network connection new methods based on one-way input technology and quantum cryptography are proposed, and its applicable occasions are analyzed. Problems to be solved on security segregation and information-exchanging product are proposed and emerging cryptology technology will be the end of physical isolation. It hope that the research results to the further development of network security perimeter protection work play a positive role.

Key words: physics isolation, electromagnetic compromising emanation, stuxnet, network security perimeter, quantum private communication