Rick Huebner rhuebner@radiks.net writes:
I run a bridge from a "semi-static" home internet account, where the address is dynamically assigned but only changes when either the ISP or my hardware router goes down and forces a reconnect, which only happens maybe once every several months. I've read in a few places that Tor bridges with dynamic IP addresses are just as useful as those with static addresses, even if their address changes pretty often, because the bridge user's client will use the bridge's fingerprint to look up its current address and port from the bridge authority if it fails to connect.
Hello Rick,
your intuition is correct. This feature does not work very well.
Here are a few reasons why:
a) As you said, UpdateBridgesFromAuthority is turned off by default. AFAIK, this is the case because the feature is not very useful atm: most places have already blocked all the Tor authorities including the bridge authority.
The feature needs to be slightly reworked. For example, maybe Tor needs to ask any working bridges it has about the descriptor of its dead bridges. Then the working bridges would query the bridge authority themselves and relay the descriptors to the client.
However, a Tor proposal is needed to implement the above feature and further analysis is required (for example, is it a good idea to reveal to a bridge what other bridges you are using). Feel free to help us out with this :)
b) Also, Tor clients are amnesiac with regards to bridges information. That is, even if they learn the fingerprint or the new IP address of a bridge, they don't write it down on a file. So next time they start up, they have to do the whole thing again. Sebastian wrote a proposal for this a few years ago, but it's still unimplemented: https://gitweb.torproject.org/torspec.git/blob/HEAD:/proposals/192-store-bri... Feel free to help with this too :) The first step is probably to reread the proposal, and see if anything needs to be changed to reflect the current state of Tor.
Also, check out this related blog post by Sebastian: https://blog.torproject.org/blog/different-ways-use-bridge
Have a good day and sorry for the sad news :)