tor/doc/spec/proposals/128-bridge-families.txt

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Filename: 128-bridge-families.txt
Title: Families of private bridges
Author: Roger Dingledine
Created: 2007-12-xx
Status: Dead
1. Overview
Proposal 125 introduced the basic notion of how bridge authorities,
bridge relays, and bridge users should behave. But it doesn't get into
the various mechanisms of how to distribute bridge relay addresses to
bridge users.
One of the mechanisms we have in mind is called 'families of bridges'.
If a bridge user knows about only one private bridge, and that bridge
shuts off for the night or gets a new dynamic IP address, the bridge
user is out of luck and needs to re-bootstrap manually or wait and
hope it comes back. On the other hand, if the bridge user knows about
a family of bridges, then as long as one of those bridges is still
reachable his Tor client can automatically learn about where the
other bridges have gone.
So in this design, a single volunteer could run multiple coordinated
bridges, or a group of volunteers could each run a bridge. We abstract
out the details of how these volunteers find each other and decide to
set up a family.
2. Other notes.
somebody needs to run a bridge authority
it needs to have a torrc option to publish networkstatuses of its bridges
it should also do reachability testing just of those bridges
people ask for the bridge networkstatus by asking for a url that
contains a password. (it's safe to do this because of begin_dir.)
so the bridge users need to know a) a password, and b) a bridge
authority line.
the bridge users need to know the bridge authority line.
the bridge authority needs to know the password.
3. Current state
I implemented a BridgePassword config option. Bridge authorities
should set it, and users who want to use those bridge authorities
should set it.
Now there is a new directory URL "/tor/networkstatus-bridges" that
directory mirrors serve if BridgeAuthoritativeDir is set and it's a
begin_dir connection. It looks for the header
Authorization: Basic %s
where %s is the base-64 bridge password.
I never got around to teaching clients how to set the header though,
so it may or may not, and may or may not do what we ultimate want.
I've marked this proposal dead; it really never should have left the
ideas/ directory. Somebody should pick it up sometime and finish the
design and implementation.