[tor-talk] Adblock for everyone

Joe Btfsplk joebtfsplk at gmx.com
Mon Oct 7 21:42:46 UTC 2013

On 10/6/2013 3:14 PM, Joe Btfsplk wrote:
> Thanks for your insight.
> On 10/6/2013 10:18 AM, Andrew Lewman wrote:
>> Adblock whitelists certain advertising companies and ads themselves:
> These white lists can easily be disabled, but then that conflicts w/ 
> Tor's concept of damaging sites' acceptance of Tor (interesting point).
> However, fingerprinting NOT with standing, millions? of Firefox & 
> other browser users, having Adblock Plus, Ghostery, etc., enabled, are 
> never turned away from websites, AFAIK.
> Just curious - by that analogy, should Fx, Chrome & others maybe 
> disallow using extensions that block ads or other things, as it may 
> cause some sites' non acceptance of browsers that allow such extensions?
> Could be wrong, but I'd bet if sites "reject" TBB, it might be because 
> of several other reasons that come before blocking ads. But...
>> Users are free to install these addons if they wish, but doing so is
>> not recommended, as it will alter the browser request fingerprint. "
> That brings up a good question.  I assume that TBB freely gives up 
> info to sites that use the query:  "navigator.plugins" - where sites 
> can query whether specific plugins are installed:
> |var isSupported = navigator.plugins['Shockwave Flash'];|... if users 
> install any plugins.
> Since TBB doesn't ship with plugins, why does TBB honor requests for 
> plugin info, at all?
> Would TBB ignoring requests for "navigator.plugins" from sites break 
> too many browser functions or ?
> As I understand, in Fx there's no equivalent method to find out all 
> installed EXTENSIONS (distinguished from plugins; collectively called 
> "addons").  But presence of SOME extensions are detectable by their 
> effect on a web site's function, such as ads or trackers being 
> blocked.  Correct?  But, not all extensions in Fx (TBB) are detectable 
> - correct?
> Thanks.
No comments from more experienced users about the possibility of TBB 
ignoring sites' requests for *most* plugins?

On 10/6/2013 10:18 AM, Andrew Lewman wrote:
> Users are free to install these addons if they wish, but doing so is
> not recommended, as it will alter the browser request fingerprint.
The word "will" means no exceptions.  Is it true that for extensions 
(not plugins), how they change TBB's fingerprint (if at all) may depend 
on their function?  Specifically, their effect, if any, on the web page 
and if that effect could be detected by the web page (or an adversary)?  
And then, only if the extension's (not plugins') specific effect on a 
web page is actually being monitored?

What site or adversary would or could monitor if an extension was 
installed, that only shows the download status / progress of a page, etc.?
If an extension doesn't alter sites' functions - at all (not talking 
about AdBlock here), doesn't send / receive data, no pinging, etc., how 
would its presence be detected, thus changing TBB's fingerprint?

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