Protecting yourself is very challenging in the hostile environment of the Internet. Imagine a global environment where an unscrupulous person from the other side of the planet can probe your computer for weaknesses and exploit them to gain access to your most sensitive secrets.

Getting access to source code . . . was kind of like the secret ingredient. I wanted to know what the secret was.

Companies spend millions of dollars on firewalls, encryption, and secure access devices and it's money wasted because none of these measures address the weakest link in the security chain: the people who use, administer, operate and account for computer systems that contain protected information.

My hacking involved pretty much exploring computer systems and obtaining access to the source code of telecommunication systems and computer operating systems, because my goal was to learn all I can about security vulnerabilities within these systems.

One of my all-time favorite pranks was gaining unauthorized access to the telephone switch and changing the class of service of a fellow phone phreak. When he'd attempt to make a call from home, he'd get a message telling him to deposit a dime, because the telephone company switch received input that indicated he was calling from a pay phone.

Most of the computer compromises that we hear about use a technique called spear phishing, which allows an attacker access to a key person's workstation. It's extremely difficult to defend against.