Until recently the term “security,” when applied to SCADA communication systems, meant only the process of ensuring message integrity in the face of electrical noise and other disturbances to the communications. But, in fact, “security” also has a much broader meaning. Security, in the broader sense, is concerned with anything that threatens to interfere with the integrity of the business.

Our focus here will be to examine issues related more narrowly to SCADA security. In an earlier section we discussed the role of the OSI reference model (ISO 7498-1) in defining acommunications architecture. In similar fashion, ISO 7498-2, Information Processing Systems, Open Systems Interconnection, Basic Reference Model – Part 2: Security Architecture, issued in 1989, provides a general description of security services and related mechanisms that fit into the reference model, and it defines the positions within the reference model where they can be provided.

It also provides useful standard definitions for security terms.

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