A system for intrusion detection in a field area network where data is transmitted via packets, includes a processor for analyzing the packets to ascertain whether the packets conform to a sets of rules indicating an intrusion, and a database for storing an alert indicating an intrusion if the packets conform to at least one rule in the sets. The sets of rules are for field network layer data, internet protocol traffic data and field area application traffic data. A method for detecting intrusion in a field area network where data is transmitted via packets, including analyzing the packets to ascertain whether the packets conform to the sets of rules, and storing an alert indicating an intrusion if the packets conform to at least one rule in the sets of rules.