[tor-bugs] #16420 [Tor]: Hide number of tor clients running on a shared network

[Tor Bug Tracker & Wiki]

#16420: Hide number of tor clients running on a shared network
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 Reporter:  Warr1024     |          Owner:
     Type:  enhancement  |         Status:  new
 Priority:  normal       |      Milestone:
Component:  Tor          |        Version:
 Keywords:               |  Actual Points:
Parent ID:               |         Points:
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 For multiple machines/users behind a single network, each machine should
 run its own tor instance (more than one, in the case of TBB's), but this
 leaks metadata about the quantity and timing of tor usage to
 eavesdroppers/ISP's.  For instance, each TBB instance will open a
 connection to its own guard on startup, so an eavesdropper can enumerate
 the number of different TBB users (for long-lived installs) and the times
 when they're most likely to be active.

 Ideally, tor should provide a mechanism to obscure the number of different
 instances running on a network, either making them all look like a single
 client, or an indeterminite number of clients with random start/stop
 times.

 To do this, at least the guards will need to be synchronized between tor
 instances (#15243).  Even with guards synchronized, each instance will
 open its own TCP connection to that guard; the TCP connections would
 either need to be multiplexed into a single connection, or split into a
 random number of independent-looking streams.

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Ticket URL: <https://trac.torproject.org/projects/tor/ticket/16420>
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