If you're interested in web privacy, then you need to be running uBlock Origin (uBO) by Raymond Hill and i should point out that the Origin version is the one you want, not one of the many ripoff versions. While many people think of uBO as an ad blocker, it is actually much more than that and this is why i do not recommend any other ad-blocking extension (uBO can be used with uMatrix however). uBlock Origin provides several privacy related settings as well as both static and dynamic filtering of web content which addresses more than just ads.
On the privacy and anti-tracking side, apparently there's a new tracking method being employed by some websites which uses CNAME records and, to my knowledge, uBlock Origin is the only add-on that addresses this method of tracking and, although uBO is available for Chrome, it addresses the new tracking method only for Firefox since the Chrome browsers lack the needed DNS API.
To enable the new CNAME tracking protection in uBlock Origin for Firefox:
- you must be running at least version 1.24.1 beta of uBO (you may want to wait until 1.24 stable lands at AMO)
- enable the "I am an advanced user" option
- click the gear icon next to the the "I am an advanced user" label
- change the value of
If you were not running uBlock in its advanced mode, you can disable the "I am an advanced user" option and the new setting will still work.
If you run only uMatrix, also by Raymond Hill, without uBlock, it looks like this feature will be added at some point.
For more, see uBlock Origin for Firefox addresses new first-party tracking method at ghacks.net and the Address 1st-party tracker blocking · Issue #780 issue on GitHub.