Head to this web site for a thorough, free check of your PC's vulnerabilities.
Do you really know how secure your PC is from intruders? Probably not. But there's a free online tool that will probe your PC for online security vulnerabilities and report to you on the results.
The site is run by the Gibson Research Corporation, and it tests your machine, trying to make connections to a handful of the most well-known and vulnerable Internet ports on your PC. The site runs two tests, reports to you on the results, and then explains what the reports mean?where you're vulnerable and how serious those vulnerabilities are. It also has a great deal of useful information about Internet security, as well as free and for-pay security software you can download. Visit the site at http://www.grc.com. You may have to do some clicking around to find the tests, but keep clicking on Shields Up! and you'll eventually get there.
The best use for the site is to test your PC's vulnerabilities, then install a firewall [Hack #46] and [Hack #48] and see the results of what you've done. It'll tell you whether there are any remaining vulnerabilities you need to fix. Figure 5-5 shows the results of a probe of a PC without a firewall. It's relatively secure, but could be more secure, because the site has found ports, even though they're closed. Figure 5-6 shows that the PC is operating in "stealth mode" after the installation of the firewall?the PC doesn't even appear to exist.