I. Introduction
The massive proliferation of traditional information and communication technologies (ICT) hardware and software into the heart of industrial control systems (ICS) has given birth to a unique technological ecosystem. Modern ICS encompass a variety of objects ranging from sensors and actuators, industrial radio-frequency identification (RFID), e.g., product tracking devices, video surveillance cameras to generic PCs, networking and security devices such as industrial Ethernet, firewall, and intrusion detection systems. These advanced ICS deliver various services and features; they improve operational benefits of control, reliability, and safety and facilitate the implementation of novel infrastructural paradigms such as smart grid.