The McAfee software has three more active components, however, that can protect you if a Trojan appears before they've detected and issued a fix, as well as to help you identify malicious Web sites you should avoid. These components let you review programs before allowing them to launch, use a firewall to prevent intrusions (useful to prevent unintended access to file sharing, even), and a Firefox extension that brands the safety of search engine results.
An Application Protection component, configured via the program's preferences, monitors software when it launches, and puts itself in the way with a pop-up prompt. You choose whether to launch with or without network access provided to the program, and allow the program to be launched once (just when you approve it) or always thereafter. Or you can deny a launch altogether. You can modify choices for individual programs or background processes later through preferences.
Such controls generally prevent software that you didn't intentionally install from being able to run and take over your Internet connection. Of course, this can't protect against exploits that use techniques to gain root access to your Mac, and install software that runs beneath the user interface's service. Apple has patched many such holes, although there is little evidence that such attacks were made from Web sites or via email.
Firewall and Firefox
The firewall is simpler than many full-featured programs, and I appreciate that. For most people, being able to click a few buttons is better than an ocean of pulldown menus and configurations. I particularly like that you can shut down all incoming or outgoing traffic or both with a couple of clicks without having to disable your network interface. You can create custom rules--only certain kinds of traffic may originate from your computer to specific addresses, or block all but a handful of services from receiving signals from the outside world. You can also define trusted networks.
Firewalls have the benefit of keeping normal services you may have switched on, like VNC-based screen-sharing (a somewhat insecure option in the Screen Sharing service in the Sharing system preferences), from being accessible or crackable when you're on an open network, such as at a coffeeshop.
If you use Firefox, McAfee's Site Advisor add-on is a big help in examining search results on Google and other engines. It's more tightly integrated with Yahoo (where it disables dangerous links entirely), but works just fine with others. When you perform a search, the advisor tags each result with a green, yellow, red, or question mark icon. McAfee constantly spiders Web sites looking for malware and other problems, and rates sites accordingly. A McAfee seal of approval appears on ecommerce sites that the firm separately evaluates.
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