Firefox 4 beta 11 has landed a useful security feature for people who are sick of "stalkertizements," those cookie-based ads that use your browsing history to target ads at your perceived tastes. The new "Do Not Track" feature in Firefox 4 beta 11 for Windows, Mac, and Linux sends out a header that tells Web sites that you want to opt out of behavioral tracking, though Mozilla cautions in a blog post that it will take some time for sites and advertisers to respond to the header.
The feature can be toggled via a check box in the Advanced tab of Firefox's Options window.
Mozilla privacy lead Alex Fowler said that the engineers decided to base the feature in the header sent from the browser because it's something that all Web pages read as they load. A blacklist or cookie-based solution would be harder to implement across different browsers. He acknowledged that successful implementation of "Do Not Track" also depends on advertisers and site owners respecting that incoming header.
He added that the initial stages of a legislative fix are under way as at least one member of Congress--Rep. Jackie Speier (D-Calif.)--plans to introduce a bill ordering the Federal Trade Commission to create a "Do Not Track" program for advertisers. However, a second bill also being proposed does not include the "Do Not Track" option. Both might have a hard time passing in today's antiprivacy climate, although a bill with "Do Not Track" would be the harder sell because of its stronger privacy controls.
Mozilla security and privacy engineer Sid Stamm has documented the technical implementation of "Do Not Track."
Other changes in Firefox 4 beta 11--which Mozilla hopes will be the penultimate Firefox 4 beta--include moving connection status messages to a small overlay window, re-enabling WebGL on Linux, disabling automatic switching to offline mode when no network connection is detected, and a redesign of the default about:home page. The full changelog is available here.