▪ Spread out your computer numbers; you might even use different telephone exchanges. Don’t have numbers adjacent to each other—like 555-1212 next to 555-1213. If you do, your computers will be easier targets for hackers with WarGames-style dialing programs that scan local exchanges for computer numbers.
That’s good advice from Zap. In the same vein, even if you have just one micro, you might consider trying to get a phone number in an exchange miles from your actual location. You might even want to use a tie line to another city. It all depends on whether you think the costs would justify the added protection; for many businesses they wouldn’t.
Also, you might keep your modem number secret from people who don’t need to know. A Hollywood director, fearful that computer-smart science-fiction fans might tap into his dial-up machine, used such a precaution. Only he and his regular callers knew the number. His super-secretive approach obviously wouldn’t have worked in a typical business, especially one with many phone lines coming in. Also, nothing’s foolproof; suppose an electronic snoop unlocks your building’s wire closet.
▪ If possible, use modems faster than 1,200 baud. Then, says Zap, “most hackers’ modems can’t keep up.” Most small computers’ modems transmit at 300 baud, about 300 letters or numbers a second.
▪ Remember that hackers can be ingenious. “Don’t be smug just because you have a dial-back modem. That’s a device that makes callers tap out a special code, and then it rings them back at their authorized location. You can get around it by tying into the central office and setting up a three-way call—without anyone hearing you. I know hackers can set up three-way calls. I’ve done it myself.”
▪ Protective devices, however, are better than nothing at all. “Despite their limitations, I’d still install a call-back arrangement or a device that asked you for a code—or maybe a combination of the two. A combination usually would be much better.”
▪ Don’t get hung up on protecting your dial-up computer with just hardware or just software—use both. “Black boxes can help keep the wrong people from breaking in. But you also need good security software to control how deeply even authorized people can get into your computer. You want some people—like customers—to have only partial access to the goodies inside your system.”
▪ Watch what you throw away. “Some hackers can log onto your dial-up computer after first poking through your trash—for printouts with passwords and similar material.” Another hacker jokingly refers to “The Dempster Dumpster Library.”
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Don’t lose track of security threats around your office itself while worrying about modems and encryption. Would you believe that you can’t absolutely erase an electronic file—say, a letter or report on your disk—just by following the directions in your software? A snoop might recover the information with a special program like Disk Doctor. Luckily, however, you can zap a sensitive file by magnetically “writing” over its part of the disk. Say you want to wipe out a letter 500 words long, File A. Well, do the following: