[tor-relays] About running an Exit node

[Tom Ritter]

On 7 May 2014 10:09, Pika ohc <pikaonthefly at outlook.com> wrote:
>    Thanks for your kindly reply. According to [1], i am still wondering if
> it is possbile to make the minimum route path length as 1 (which default is
> set to 3) and set Exitnodes to my server as default exit nodes in the
> clients' torrc. Moreover, if the setting I mentioned is possible, the client
> can send all the traffic directly to my server and ask my server(exit node)
> to relay to the destination, where the scenario may be as the same as that
> described on [1]. Sorry for asking the question again with your answer.  And
> looking forward to the answers. :)

An exit node checks the prior node in the path, and if it is not part
of the Tor Network, will not allow a single-hop path to be built
through it*.  This settings can be disabled on the ExitNode (that is,
you can explicitly allow that behavior) by setting
ExcludeSingleHopRelays.
(https://www.torproject.org/docs/tor-manual.html.en#ExcludeSingleHopRelays)

I suspect that someone could trick the Exit Node by running a tor
relay and building a SingleHop circuit through your exit node from the
same machine running the relay - but generally speaking this is not
something you should worry about, as it affects everyone equally.

-tom

* Take these statements at a high level, and if you want to know
_exactly_ how it 'checks if it's part of the network' or 'checks the
prior node in the path', you should read the source.