he security of networked computers is all about making sure that the
right people have access to the right information, and that they get it intact
without anyone listening in as the information is transmitted. To accomplish
those goals, you have to be sure that people are who they claim to be. You
also have to have a way of dealing with security breaches while—and after—
they occur, so you can figure out what is (or was) going wrong in order to
correct the problem. The difference between security on a local area network
(LAN) and security on the Internet is largely one of scale. The threats...