Practical UNIX and Internet Security, 3rd Edition

Planning Your Security Needs

There are many different kinds of computer security, and many different definitions. Rather than present a formal definition, this book takes a practical approach and discusses the categories of protection you should consider. Basically, we know a computer is secure if it behaves the way you expect it to. We believe that secure computers are usable computers and, likewise, that computers that cannot be used, for whatever the reason, are not very secure.

Types of Security

Within our broad definition of computer security, there are many different types of security that both users and administrators of computer systems need to be concerned about:

Confidentiality

Protecting information from being read or copied by anyone who has not been explicitly authorized by the owner of that information. This type of security includes not only protecting the information in toto, but also protecting individual pieces of information that may seem harmless by themselves but can be used to infer other confidential information.

Data integrity

Protecting information (including programs) from being deleted or altered in any way without the permission of the owner of that information. Information to be protected also includes items such as accounting records, backup tapes, file creation times, and documentation.

Availability

Protecting your services so they’re not degraded or made unavailable (crashed) without authorization. If the systems or data are unavailable when an ...