Application layer security proxy for smart Grid substation automation systems

America's electrical power industry, in conjunction with government, is developing Smart Grid technologies to improve electrical power efficiency and reliability. This move is creating challenges in transitioning originally isolated proprietary systems to more open ones, connecting them to enterprise-level and other networks without compromising their original control performance. Application layer communication is the weakest link in terms of security and the unique challenges of Smart Grid applications have not been addressed yet. This paper presents a security solution based on application layer security proxy, which deploys deep packet inspection and role-based access control technologies, for smart grid substation automation systems. The testing of the prototype system shows that it is able to block illegitimate packets without interrupting its communication session.