[tor-relays] Understanding Reduced Exit Policies..?

[Moritz Bartl]

Hi Jeremy,

On 09/12/2014 05:02 AM, Jeremy Olexa wrote:
> My question: If I want to "try" being an exit node and add allowed
> exit ports slowly, does that help the network or not? For example,
> month 1: allow port 22, month 2: allow IRC ports, and so-on. How does
> the client path selection work in this case - is it smart enough to
> pick my exit when needed?

Yes and no. You can slowly add more ports, but unless you allow port 80,
443 and 6667 your relay won't get the Exit flag. [1] Tor clients
preemptively open some circuits to such exits by default, and will use
existing circuits unless none of the existing circuits allow the
destination address or port. So, if you want to help "best", you should
open at least these three ports. It is a fine strategy to then add more
and more ports over time, but the other way round is also quite
reasonable (starting with the Reduced Exit Policy and remove ports on
complaints).

The Reduced Exit Policy is most helpful in reducing DMCA complaints for
Bittorrent traffic: Bittorrent by default picks a random port, and it
largely reduces the probability of your exit being picked if you just
allow ~200 instead of 65534 ports.

Thanks for running a relay!

Moritz

[1]
https://gitweb.torproject.org/torspec.git?a=blob_plain;hb=HEAD;f=dir-spec.txt