Practical UNIX and Internet Security, 3rd Edition

Protecting Your Data

There is a strong overlap between the physical security of your computer systems and the privacy and integrity of your data. After all, if somebody steals your computer, they probably have your data. Unfortunately, there are many attacks on your data that can circumvent the physical measures mentioned in earlier sections.

This section explores several different types of attacks on data and discusses approaches for protecting against these attacks. It recapitulates some advice given elsewhere in the book in the context of physical security.

Eavesdropping

Electronic eavesdropping is perhaps the most sinister type of data piracy. Even with modest equipment, an eavesdropper can make a complete transcript of a victim’s actions—every keystroke and every piece of information viewed on a screen or sent to a printer. The victim, meanwhile, usually knows nothing of the attacker’s presence and blithely goes about his work, revealing not only sensitive information but also the passwords and procedures necessary for obtaining even more information.

In many cases, you cannot possibly know if you’re being monitored. Sometimes you will learn of an eavesdropper’s presence when the attacker attempts to make use of the information obtained. Often, you cannot prevent significant damage at that point. With care and vigilance, however, you can significantly decrease the risk of being monitored.

Encryption provides significant protection against eavesdropping. Thus, in many cases, ...