[tor-dev] Desired exit node diversity

Roger Dingledine arma at mit.edu
Thu Sep 24 05:18:47 UTC 2015

On Wed, Sep 23, 2015 at 06:18:58AM +0000, Virgil Griffith wrote:
> Exit nodes seem a nice place to start concretizing what's meant when we say
> we want relay diversity. Comments immensely appreciated because as-is I
> don't know the answers to these questions.

Hi Virgil,

I've been pondering the opposite of this topic, after looking at the
recent tor-relays thread about some ISP not wanting to let somebody
host an exit relay because they figure a lot of the Tor network is
run by government agencies. My usual answer to that concern is "no, we
*know* the operators of more than half the capacity in the Tor network,
so this cannot be the case". And I think this is increasingly true in
the era of activist non-profits that run relays -- Germany's got one,
and so do the US, the Netherlands, Sweden, France, Luxembourg, etc etc.

But it would be neat to have a mechanism for learning whether this is
actually true, and (whatever the current situation) how it's changing.

The tie-in to Roster would be some sort of "socially connected" badge,
which your relay gets because you're sufficiently tied into the Tor
relay operator community.

And then we'd have something concrete to point to for backing up, or
disputing, the claim that we know a significant fraction of the network.

Of course, the details of when to assign the badge will be tricky and
critical: too loose and you undermine the trust in it (it only takes a
few "omg the kgb runs a relay and look it's got the badge" cases to make
the news), but too strict and you undercount the social connectedness.

In a sense this is like the original 'valid' flag, which you got
by mailing me and having me manually approve your relay (and without
which you would never be used as the entry or exit point in a circuit).
Periodically I wonder if we should go back to a design like that, where
users won't pick exit relays that don't have the "socially connected"
badge. Then I opt against wanting it, since I worry that we'd lose
exactly the kind of diversity we need most, by cutting out the relays
whose operators we don't know.

But both sides of that are just guessing. Let's find out!


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