NOVELTY - The system (12) has a device monitoring component (40) for measuring control system behavior. An intrusion prevention system (10) is communicatively coupled to the monitoring component and a communication network (18). The intrusion prevention system comprises a control system analysis component (38) to analyze the behavior measured by the monitoring component against a first rule set to determine whether an anomaly and an intrusion are present. A network analysis component (36) analyzes network data from the network against a second rule set to determine whether the anomaly occurs.    USE - Industrial control system e.g. gas turbine system, gasification system, steam turbine system, wind turbine system, water turbine system, electrical power generation system and power grid automation system (all claimed), for detecting digital security breaches or intrusions to monitor network connections e.g. network traffic, file system access/modifications and operating system/library calls, in a communication network i.e. internet. Can also be used as a heat recovery steam generator (HRSG) system, combustion system and an automated manufacturing system e.g. chemical plant and oil refinery.    ADVANTAGE - The system allows the intrusion to cause the system to transmit the data through network connections that are not requested, so that the system can reduce the intrusion to monitor the network connections in the system and additional parameters in the system can be monitored to improve security of the system.    DETAILED DESCRIPTION - The control system behavior comprises behavior of a controller (16). INDEPENDENT CLAIMS are also included for the following:    (1) method for detecting security breaches in an industrial control system    (2) a computer program comprising a set of instructions for detecting security breaches in an industrial control system.    DESCRIPTION OF DRAWING(S) - The drawing shows a schematic block diagram of an intrusion prevention system (IPS) within an industrial control system.    Intrusion prevention system (10)    Industrial control system (12)    Controller (16)    Communication network (18)    Network analysis component (36)    Control system analysis component (38)    Device monitoring component (40)