Your own computer may be a trouble spot for Internet security. If you have a DSL line, broadband cable modem or other connection to the Internet that is up and running 24 hours (including T1 at the office without a firewall or NAT), unlike a modem-and-phone-line connection, be sure to turn your computer off when you are not using it. Most home PCs have pitifully poor security compared to the Unix workstations that power most commercial Web sites.

System crackers search for vulnerable, unattended DSL-connected home computers, and can invade them with surprising ease, sniffing through files looking for credit card numbers or other sensitive data, or even "taking over" the computer and quietly using it for their own purposes, such as launching attacks on other computers elsewhere - attacks you could initially be blamed for. Firewall hardware and software is another option that can protect you from these kinds of attacks.

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