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-5901597ad...
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.