February 2008: A company that boasts it provides “total fire protection systems” went up in flames. Smoke was seen coming from the warehouse-like buildings that house Atlantica Mechanical of Dartmouth控制工程网版权所有, Nova Scotia —a contracting business that oversees the design控制工程网版权所有, installation and maintenance of fire protection systems. The local fire department struck the blaze, but the building and contents were lost.
　　Ask a diverse crowd of people to define the term “security” and the responses will likely

include financial securities; fire protection; natural disaster protection; protection against unauthorized access to propertywww.cechina.cn, computers, and personal I.D.; protection against un-insured motorists; and many more similar concepts that tend to center on physical things.
　　Conduct a similar exercise with business executives and the responses will likely include cyber security; protection of intellectual properties; protection of critical business information; protection of personnel, facilities, assets, and the environment.
　　What these and the many other responses you hear illustrate is that most people consider security synonymous with defense—defense against unexpected interruptions to our daily activities.
　　Frequently, businesses will approach security using a domain-by-domain approach—protect the perimeter, protect the people, protect the intellectual propertywww.cechina.cn, protect the environment, and so forth. However, when you step back and look at itwww.cechina.cn, security is really about ensuring business continuity and it is best achieved by designing a unified defense-in-depth strategy and architecture that can defend against myriad possible business interruptions.

　　Medieval concepts of defense-in-depth still apply in newer forms. Source: control Engineering

　　Businesses have been aggressively engaged in establishing a strong defense against unauthorized access to their digital systems for about the last 20 years. Today we generally refer to these defensive efforts as cyber security, and