About Tor Browser Extensions

Why Tor devs doesn’t add built in Ad blocker & Tracker blocker to Tor Browser?? They did added some extensions too like NoScript, Https Everywhere etc. Nobody wants to see annoying ads plus more or less all the ads tracks users activities. And there has trackers hidden beneath. Isn’t it be more effective as per privacy & anonymity aspect if there has ads & trackers blocker? So, we can’t be tracked by some rouge individuals? It’s a privacy oriented feature of course. But I’m wondering why Tor devs doesn’t even care yet. It would be great if Tor browser comes with uBlock Origin by default.

Also I heard that in ‘Tails OS’ the Tor browser has built in uBlock Origin addon. So, what Tails OS devs thinking? Isn’t it makes more vulnerable to fingerprint? If Tor devs added the uBlock Origin too then there would be no more fingerprinting issue.

All I want to block all the annoying ads & don’t want to be tracked while browsing Tor network. Hope, Tor devs will add this near future.

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I have asked myself the same question. But after careful consideration, it is probably correct that the browser ships without a pre-installed adblocker.
First of all, here is the official statement: Should I install a new add-on or extension in Tor Browser, like AdBlock Plus or uBlock Origin? | Tor Project | Support
I think it would be a lot of work to integrate a blocker. You have to make sure that nothing is logged. And you have to make sure that the blocker doesn’t send unwanted data to the internet that you don’t know about.
But there is another reason. The Tor browser is supposed to guarantee people a free internet. But with a pre-installed adblocker, it will happen that you will not be able to read a lot of content, because some websites block adblocker users. Now you and I know about the function of an adblocker. Especially how to add exceptions and so on. But not everyone knows that.So it could happen that you exclude less knowledgeable users who are looking for a borderless internet from content or impose a fallback to a paywall.

So, in my opinion, it is not only a technical question, but also a political one.

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From the Tor Browser design document:

  1. No filters: Site-specific or filter-based addons such as AdBlock Plus, Request Policy, Ghostery, Priv3, and Sharemenot are to be avoided. We believe that these addons do not add any real privacy to a proper implementation of the above privacy requirements, and that development efforts should be focused on general solutions that prevent tracking by all third parties, rather than a list of specific URLs or hosts. Implementing filter-based blocking directly into the browser, such as done with Firefox’ Tracking Protection, does not alleviate the concerns mentioned in the previous paragraph. There is still just a list containing specific URLs and hosts which, in this case, are assembled by Disconnect and adapted by Mozilla. Trying to resort to filter methods based on machine learning does not solve the problem either: they don’t provide a general solution to the tracking problem as they are working probabilistically. Even with a precision rate at 99% and a false positive rate at 0.1% trackers would be missed and sites would be wrongly blocked. Filter-based solutions in general can also introduce strange breakage and cause usability nightmares. For instance, there is a trend to observe that websites start detecting filer extensions and block access to content on them. Coping with this fallout easily leads to just whitelisting the affected domains, hoping that this helps, defeating the purpose of the filter in the first place. Filters will also fail to do their job if an adversary simply registers a new domain or creates a new URL path. Worse still, the unique filter sets that each user creates or installs will provide a wealth of fingerprinting targets. As a general matter, we are also generally opposed to shipping an always-on Ad blocker with Tor Browser. We feel that this would damage our credibility in terms of demonstrating that we are providing privacy through a sound design alone, as well as damage the acceptance of Tor users by sites that support themselves through advertising revenue. Users are free to install these addons if they wish, but doing so is not recommended, as it will alter the browser request fingerprint.



What do you think of uMatrix? Some say that it is more effective than any ad blocker and noscript combined. If it doesn’t change fingerprints, then we could consider it as a universal solution for the Tor browser.