Opened 5 years ago

Last modified 3 years ago

#16420 new enhancement

Hide number of tor clients running on a shared network

Reported by: Warr1024 Owned by:
Priority: Medium Milestone: Tor: unspecified
Component: Core Tor/Tor Version:
Severity: Normal Keywords: guard, topology tor-client shared-state prop247-related
Cc: Actual Points:
Parent ID: Points: large
Reviewer: Sponsor:


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.

Child Tickets

Change History (8)

comment:1 Changed 5 years ago by Warr1024

This can ALMOST be accomplished today by running a private bridge and having each client use that bridge, except that bridges act as entry guards for circuit-building today. The problem is that bridge circuits are { client, bridge, middle, exit } but should really be { client, bridge, guard, middle, exit } for this (and possibly other) applications.

comment:2 Changed 5 years ago by nickm

Milestone: Tor: 0.2.8.x-final

comment:3 Changed 5 years ago by nickm

Points: large

comment:4 Changed 5 years ago by nickm

Milestone: Tor: 0.2.8.x-finalTor: 0.2.???
Severity: Normal

comment:5 Changed 4 years ago by teor

Milestone: Tor: 0.2.???Tor: 0.3.???

Milestone renamed

comment:6 Changed 4 years ago by nickm

Keywords: tor-03-unspecified-201612 added
Milestone: Tor: 0.3.???Tor: unspecified

Finally admitting that 0.3.??? was a euphemism for Tor: unspecified all along.

comment:7 Changed 3 years ago by nickm

Keywords: tor-03-unspecified-201612 removed

Remove an old triaging keyword.

comment:8 Changed 3 years ago by nickm

Keywords: guard topology tor-client shared-state prop247-related added
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