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(DCS) and Programmable Logic Controllers (PLC). On the other hand, industrial communications lines are usually based on TCP/IP protocols. In the further text, we provide a brief analysis of industrial control systems and their communications lines. An Overview of Industrial Control Systems Industrial control system (ICS) is a global term that covers several types of control systems such as Supervisory Control and Data Acquisition (SCADA) systems, Distributed Control Systems (DCS), and configurations like Programmable Logic Controllers (PLC). ICS are normally used in industries such as electrical, water, oil and natural gas, chemical, transportation, pharmaceutical, pulp and paper, food and beverage, and discrete manufacturing. These control systems are critical to the operation of critical infrastructures. The high percentage of critical infrastructures are privately owned and operated. Actual implementations of ICS may be hybrids that blur the line between DCS and SCADA systems by incorporating attributes of both. SCADA systems are highly distributed systems used to control geographically dispersed assets, usually scattered over thousands of square kilometers, where centralized data acquisition and control are crutial to system operation. These systems are applied in distribution systems such as water distribution and wastewater collection systems, oil and natural gas pipelines, electrical power grids, and railway transportation systems. A SCADA control center plays role of centralized monitoring and control for field sites over long-distance communications networks which include monitoring alarms and processing status data. Automated or operator-driven supervisory commands from remote stations can be sent to remote station control devices, which are well-known as field devices. Field devices control local operations, collecting data from sensor systems and monitoring the local environment for alarm conditions. DCS are used to control industrial processes such as electric power generation, oil refineries, water and wastewater treatment, and chemical, food, and automotive production. DCS architecture consists of a supervisory level of control overseeing multiple. They are integrated sub-systems which purpose is to control the details of a localized process. The entire control is usually achieved by deploying feed back or feed forward control loops. The desired product and/or process tolerance around a specified set point can be accomplished using specific PLCs in the field and proportional, integral, and/or derivative settings. PLCs are computer-based controllers that control industrial equipment and processes. PLCs are control system components used throughout SCADA and DCS systems. They are often used to provide operational control of discrete processes such as automobile assembly lines and power plant soot blower controls. PLCs are widely applied in almost all industrial processes. Introduction to TCP/IP Protocols Transmission Control Protocol/Internet Protocol (TCP/IP) was a network architecture developed by United States Department of Defense for its research network - ARPANET at the mid-1970s. + % %! ! & , ! . !( %+ ' "! "#+% ' - + % !& , ! % '& % & %) *"% *