Why not add the ability to add a proxy in the circuit after the exit node in case a website is blocking Tor?

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Why not add the ability to add a proxy in the circuit after the exit node in case a website is blocking Tor?

I know that this theoretically decreases anonymity but it still provides better anonymity than using nothing or just a proxy.

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Hey there !

I don’t know if it will be implemented one day but you can find a 2016 answer from dcf here : Breaking through censorship barriers, even when Tor is blocked | Tor Blog

Using “exit bridges” as you suggest might not work, because many services (including CloudFlare) don’t block Tor using a blacklist of exit nodes, rather have some automated system that detects abuse (like comment spam) and blocks IP addresses when it gets too high. (See the CloudFlare support page, Does CloudFlare block Tor?)

And here is a recent research paper about it : https://www.freehaven.net/anonbib/cache/exit-bridge-onion-services.pdf

edit : added direct link to the pdf paper

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I think that’s just a palliative solution that wouldn’t help Tor users in the medium term. For regular Tor users, that would not scale well. But, if you’re trying to solve the Captcha issue and/or websites blocking Tor users, there are more interesting projects and approaches.

For example:

  1. Monitoring Exit nodes IP reputation and Captchas. We could work with exit nodes operators to rotate their IP addresses more frequently.
  2. A ‘Privacy-pass’ like solution. A project that would require more engineering work, but it would be interesting is to add tokens to Tor.
  3. Running an unblock Tor campaign. It’s impossible to reach out to all the websites blocking Tor, but what about the most popular one?
  4. Finally, there’s an interesting demo here about the concept of ‘Exit Bridges’:

Tor exit blocking, in which websites disallow clients arriving from Tor, is a growing and potentially existential threat to the anonymity network. We introduce two architectures that provide ephemeral exit bridges for Tor which are difficult to enumerate and block. Our techniques employ a micropayment system that compensates exit bridge operators for their services, and a privacy-preserving reputation scheme that prevents freeloading. We show that our exit bridge architectures effectively thwart server-side blocking of Tor with little performance overhead. Bypassing Tor Exit Blocking
Video presentation: https://dl.acm.org/doi/10.1145/3372297.3417245

edit: added link to video presentation.

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