[tor-relays] torservers.net: some exits became guards? (deanonymization risk)

[nusenu]

Hi Paul,

Paul Syverson:
> It shouldn't be possible
> to use the relay in both positions simultaneously.  And even if it
> could serve as both guard and exit simultaneously, the route-selection
> algorithm would preclude it being used as both ends for any
> circuit. And if all torservers.net relays are properly indicated to be
> from the same family, they will never be selected for both ends of a
> circuit.

I'm well aware of how MyFamily works :)

To quote the page I linked (OrNetStats):

> Operators are only listed if they actually have a chance to do end-to-end correlation attacks, that is:
>     their guard and exit probability is > 0%
>     they did not properly configure MyFamily
>     they run in more than a single /16 network block

For more context see:
https://medium.com/@nusenu/some-tor-relays-you-might-want-to-avoid-5901597ad821


> Potentially, a client opening multiple circuits through multiple
> guards (so not using the current standard default of using a single
> guard) could have some guards and some exits of concurrent circuits
> run by torservers.net if they satisfy the /16 separation.
> But that is generally not what is meant by 'end-to-end correlation'.

By end-to-end correlation I mean "a tor client has a chance to use
torservers.net relays in their entry (guard) and exit position in a
single circuit.


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