[tor-bugs] #4806 [Tor Client]: Detect and warn when running IPv6-using client without IPv6 address privacy

[Tor Bug Tracker & Wiki]

#4806: Detect and warn when running IPv6-using client without IPv6 address privacy
-------------------------+--------------------------------------------------
 Reporter:  nickm        |          Owner:                    
     Type:  enhancement  |         Status:  needs_revision    
 Priority:  major        |      Milestone:  Tor: 0.2.4.x-final
Component:  Tor Client   |        Version:                    
 Keywords:  ipv6         |         Parent:                    
   Points:               |   Actualpoints:                    
-------------------------+--------------------------------------------------
Changes (by rransom):

  * status:  new => needs_revision


Comment:

 cmouse posted a patch to check for MAC-leaking interfaces on Linux on
 startup.  It needs some (cosmetic and non-cosmetic) changes to fit into
 Tor's style (cmouse is working on those), and some further design:

  * The function should report what it learns in a return value, not just
 in log messages, but it's not clear what needs to be returned.  I
 suggested a simple tri-state ((a) no MAC-leaking interfaces found, (b)
 MAC-leaking IPv6 interface found, (c) don't know); Sebastian pointed out
 that that's not enough information to help the user fix a per-interface
 problem (but I'm not sure that's relevant on Linux).
  * This function should be called more often than just once at startup.
 Is calling it whenever Tor detects that the computer's IP address changes
 often enough?  Does Tor detect changes to a computer's set of IPv6
 interface addresses?
  * Someone will want to silence the warnings.
  * Someone will have a horrible connection and change IP addresses often,
 and should not be spammed with warn-level messages if they don't have time
 to (or don't want to) fix their MAC leak.
  * Someone will use a MAC changer, and not want to be warned that their
 computer is leaking its current (one-session-only) MAC.

-- 
Ticket URL: <https://trac.torproject.org/projects/tor/ticket/4806#comment:3>
Tor Bug Tracker & Wiki <https://trac.torproject.org/>
The Tor Project: anonymity online