[tor-talk] Identifying use of relay as an Entry node

[grarpamp]

> But I didn't understand the original question. Are you asking if relays
> can enumerate the clients that use them for their first hop? If so, yes.
> See also point f on https://www.torproject.org/download/download#warning

Yes, that is the question being asked. Whether or not any given relay
can tell if a given connection being made to it is in fact as the first of
the three relays (entry node) that a client has chosen for its circuit.
ie: detecting with exclusive certainty the parenthesized relationship below.

(client > EntryNodeRelay) > relay > relay > [to internet/hiddenservice]

And I presume that once the entry knows it is being used as such by a
client, it can be instrumented with code to follow all of that clients network
activity (time/size/etc) resulting from that particular relationship?

And even if the client is also acting as a relay, by further discriminating
in its following of such activity between activity which is a result of the
entry relationship, and the activity of the plain relay relationship where
a third party is serving as the entry node?