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The security layer is not as static as other parts of the information infrastructure; it changes and evolves new countermeasures constantly. I don't try to keep up with everything, but I do pay attention. Two books have caught my attention, one because it is a cookbook for Linux security, a time saver, and the other because it covers other things I don't deal with, but having the knowledge helps one make connections. My third and more personal reason is I do not like being surprised. When you have enough bad experiences with security issues, you come to understand this.
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