[tor-bugs] #25723 [Circumvention/Snowflake]: Multiplex - one client splits traffic across multiple proxies

[Tor Bug Tracker & Wiki]

#25723: Multiplex - one client splits traffic across multiple proxies
--------------------------------------------+--------------------------
 Reporter:  dcf                             |          Owner:  dcf
     Type:  defect                          |         Status:  assigned
 Priority:  Low                             |      Milestone:
Component:  Circumvention/Snowflake         |        Version:
 Severity:  Normal                          |     Resolution:
 Keywords:  anti-censorship-roadmap-2020Q1  |  Actual Points:
Parent ID:  #19001                          |         Points:
 Reviewer:                                  |        Sponsor:
--------------------------------------------+--------------------------

Comment (by dcf):

 A design sketch for accomplishing this, extending the code changes that
 enabled Turbo Tunnel:

 https://lists.torproject.org/pipermail/anti-censorship-
 team/2020-February/000059.html
 > I think we can ultimately do a lot better, and make better use of the
 available proxy capacity. I'm thinking of "striping" packets across
 multiple snowflake proxies simultaneously. This could be done in a round-
 robin fashion or in a more sophisticated way (weighted by measured per-
 proxy bandwidth, for example). That way, when a proxy dies, any packets
 sent to it would be detected as lost (unacknowledged) by the KCP layer,
 and retransmitted over a different proxy, much quicker than the 30-second
 timeout. The way to do this would be to replace
 [https://gitweb.torproject.org/pluggable-
 transports/snowflake.git/tree/common/turbotunnel/redialpacketconn.go?id=7043a055f9fb0680281ecffd7d458a43f2ce65b5
 RedialPacketConn]—which uses one connection at a time—with a
 MultiplexingPacketConn, which manages a set of currently live connections
 and uses all of them. I don't think it would require any changes on the
 server.

--
Ticket URL: <https://trac.torproject.org/projects/tor/ticket/25723#comment:8>
Tor Bug Tracker & Wiki <https://trac.torproject.org/>
The Tor Project: anonymity online