Abstract:Widely available, lowcost Internet Protocol (IP) devices are now replacing specialized proprietary control protocols in Distributed Numerical Control (DNC) system, which increases the possibility of cyber security vulnerabilities and incidents. In order to analyze the security of protocol in DNC system, in this paper, a cyber range technique for building DNC system is proposed. The potential risks against DNC system are then revealed based on the security analysis on the acquired boundary protocol. Respective to the risks, the boundary protection policies are formulated at last, suggesting the protection measures taken for real manufacturing industry.