On 30 Sep 2015, at 12:01, Nick Mathewson <nickm@torproject.org> wrote:
[This isn't done yet, but I've shown it to enough people that I should share it with the list.]
1. Introduction and background
1.1. Motivation
Frequently, we find that very old versions of Tor should no longer be supported on the network. To remove relays is easy enough: we simply update the directory authorities to stop listing them.
But to disable clients is harder. We can do as we did with v1 directories in Tor 0.2.0.5-alpha, and make them know about no relays at all.
... 1.2. History
Early versions of Tor checked the recommended-versions field in the directory to see whether they should keep running. If they didn't recognize
their own version, they would stop (what?).
... 3.2. Disabling versions prior to 0.2.4.11-alpha.
Starting in version Tor 0.2.4.11-alpha, we implemented proposal 214. This proposal added a new link protocol, version 4. Earlier version versions of Tor never support it; newer versions of Tor always advertise their support for it.
We could treat the presence of any link protocol of version 4 or later as indicating the presence of 0.2.4.11-alpha. Upon receiving a version 3 or earlier as indicating the presence of a version less than 0.2.4.11-alpha. connection from such a version, we could throttle the bytes we give it, drop its circuits, or stop reading.
[TODO: which?]
Tim Tim Wilson-Brown (teor) teor2345 at gmail dot com PGP 968F094B teor at blah dot im OTR CAD08081 9755866D 89E2A06F E3558B7F B5A9D14F