How secure is your computer anyway?

YOU CAN PULL your blinds and shut your door, but when you go online you still might be sacrificing your privacy, often without your knowledge.

From advertisers and other corporations tracking your movements on the Web by placing innocuous sounding "cookies" on your hard drive, to rogues filling your e-mail box with offers of bogus university degrees or cheap printer toner, every bit of spam -- the wired word for junk e-mail -- and news item about abuses of privacy on the Net raises the hackles of Web watchers.

It was recently discovered that DoubleClick, the Internet's largest advertising company, was tracking Web users by name and address as they moved from one Web site to the next. Before that, Intel -- the makers of Pentium processors which power many of the PCs in homes and offices -- took some flak when it was discovered that some of its Pentium II and Celeron chips were shipped with an activated serial number which could ultimately identify its users. The company eventually released a program which would turn off the serial number function, designed to link users' movements on the Internet for marketing and other purposes, but many privacy experts said "not enough."

Cookies, however, are an easier matter to deal with. Stored in a folder called Cookies (in your Windows folder) or a text file called cookies.txt, cookies are strings of seemingly random characters which a Web server places on your computer. The next time you visit that Web site, its Web server can retrieve that cookie, or bit of information about you, allowing the site or advertiser to "remember" you. What is even spookier is that Web sites which you've never visited can also access your information if the original Web site is sharing its data with others.

The easiest way to avoid cookies is to simply turn them off in your browser. To disable cookies in your browser, follow the instructions at <http://www.junkbusters.com/ht/en/ cookies.html#disable>. It's simple enough to do, but there are too many different versions of Netscape Navigator and Internet Explorer to detail the various methods in a column of this size. Be warned: once you've disabled your cookies (what an odd turn of phrase), you may not be able to use some Web sites which rely on them, like Amazon and Yahoo. One option is to tell your browser to advise you before accepting any cookie. You can then use your discretion which cookies to accept. Another option is to opt out of cookie tracking. Some of the larger online advertising companies allow this, but in each case, you must go to their sites to find out how to do it. See <http:// www.precipice.org/privacy/> for a list of ad companies, including the aforementioned DoubleClick, which offer an opt-out feature.

One useful exercise to test how otherwise secure your computer is can be found at <http://grc.com>. This site opens with an invitation to use its free online diagnostic tools. If you take it up on its offer by clicking on the "Shields UP!" link, you'll likely be welcomed by name (that's the first thing the site could find out about you by rooting around your system) and the vaguely pornographic sounding invitation to use its free online diagnostic tools: "test my shields" and "probe my ports". If it finds security holes, it will make recommendations on how to plug them.

Next time, I'll examine the issue of spare, how to avoid it and, happily, how to get even with the senders.