On 6/19/12 2:30 AM, Jacob Appelbaum wrote:
146 Add new flag to reflect long-term stability
From time to time we get the idea of having clients ship with a reasonably recent consensus (or a list of directory mirrors), so instead of bootstrapping from one of the authorities, they can bootstrap from a regular directory cache. The problem here is that by the time the client is run, most of the directory mirrors will be down or will have changed their IP. This proposal tries to address that. It needs analysis based on behavior of actual routers on the network to see whether it could work, and what parameters might work. Nevertheless, we should really do something like this, so that we can ship a list of initial directory mirrors with Tor (possibly via the "fallback consensus" deisgn), so that new bootstrapping Tor clients don't all hammer the directory authorities. (6/2012)I almost wonder if the guard flag is essentially the same set of constraints? I think we should discuss this at the TorDev in Italy if possible...
A part from the performance reason that's also a censorship-bypass reason.
For example currently in China all the TorDA are fully "IP Filtered" ( not even ping are allowed to those IP addresses).
That means that even if we found a way to fuck the GFW active-probe-filter for a while, the Tor clients already existing and residing in china would not be able to connect because they cannot reach the "software-hard-coded" tor directory authority.
Imho it would be also required to consider, within that proposal, a way to "dynamically" append the latests network-map available when a user is going to download Tor.
That way when a release X is done, it automatically get the map of the build-time.
But if everytime a user download the software, the latests network map is populated, it would increase the chance to bypass static ip filters.
-naif