[tor-dev] exit-node block bypassing

Griffin Boyce griffin at cryptolab.net
Wed Jan 1 06:33:04 UTC 2014

Hey Ximin,

   I don't think it's been discussed in-depth before (at least not 
on-list), but I've thought a fair bit about it. While it's an 
interesting idea, I don't think that the risks for deploying it far 
outweigh any minor reward that could come of it.  This idea has come up 
several times in the context of Cupcake "wouldn't it be great if we 
could" sort of thing.  It really wouldn't.

   Exit node operators take on some pretty serious legal and security 
risks if they operate their exit from home. (NEVER DO THIS).  More than 
one person has been raided by police who didn't do their due diligence 
beforehand.  Expanding that into the territory of people who aren't 
fully aware of their risks would have terrible repercussions.

   It also becomes trivial to flood the Tor network with bad ephemeral 
exits, which disappear before people catch on.  Speed would be an issue 

   While I really believe that expanding Flashproxy and Fog and Bridges 
is extremely important, I don't that's plausible for exit points.  
Educating groups of website owners about censorship would help us a lot. 
  Circumvention isn't something that's thought a lot about in the US, 
which unfortunately is where a lot of large websites are based.  
Unblocking all or portions of [big website] can be extremely helpful to 
at-risk groups of people, and that's not always obvious to sysops.


Il 31.12.2013 06:07 Ximin Luo ha scritto:
> Hey all,
> Flashproxy[1] helps to bypass entry-node blocks. But we could apply
> the general idea to exit-nodes as well - have the exit-node connect to
> the destination via an ephemeral proxy. The actual technology probably
> needs to be different since we can't assume the destination has a
> flashproxy (websocket/webrtc) PT server running, but we could probably
> find a technical solution to that.
> However, I talked this over with a few people and there might be legal
> and security issues. A few points:
> - running an exit node carries a great risk, it would be bad/unethical
> to let ephemeral proxy runners take this risk
> - (for security reasons we don't fully understand) there is a process
> for trusting exit nodes and/or detecting misbehaviour (I see badexit
> emails from time to time). this would be made much harder if exits
> were ephemeral.
> - someone could create a massive number of ephemeral exit nodes and
> capture a lot of exit traffic, giving them extra data to de-anonymise
> people.
> I was wondering if any of these have been discussed in depth before
> already, or if the general topic of exit-node block bypassing is
> something to be explored.
> X
> [1] http://crypto.stanford.edu/flashproxy

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