[tor-bugs] #21493 [Core Tor/Tor]: When reachable addresses change, mark connections using those addresses

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#21493: When reachable addresses change, mark connections using those addresses
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 Reporter:  teor          |          Owner:
     Type:  defect        |         Status:  new
 Priority:  Medium        |      Milestone:  Tor: unspecified
Component:  Core Tor/Tor  |        Version:
 Severity:  Normal        |     Resolution:
 Keywords:  ipv6          |  Actual Points:
Parent ID:                |         Points:  1
 Reviewer:                |        Sponsor:
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Comment (by cypherpunks):

 Replying to [comment:2 teor]:
 > Replying to [comment:1 cypherpunks]:
 > > Replying to [ticket:21493 teor]:
 > > Are you sure about both? Personally,
 > > > When a client's reachable addresses change, we should:
 > > > * mark connections that are on non-preferred connections as "not for
 new streams".
 > > this seems fine to me
 > > > * close connections that are on newly unreachable addresses
 > > not so sure about this.
 > >
 > > There are situations when it's preferable to leave existing streams
 be, but fewer (I can't think of any) when it would be bothersome to leave
 them alone.
 >
 > I can think of several, in approximate order of prevalence:
 > * the client wants their unreachable connections to fail and be
 reestablished, rather than waiting for them to time out,
 > * the client has moved to a network where data to some IP addresses is
 restricted or costly, and they want to avoid those addresses,
 > * the client has moved to a network where connecting to certain IP
 addresses is bad for their anonymity.
 Good points. Additionally, keeping in mind things like long-running non-
 resumable transfers, IRC, and similar applications where a broken
 connection is a nuisance, and times when the client wants to keep a change
 in their reachable addresses (that could be due to changing location)
 private, it seems best for this behavior to be configurable.

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Ticket URL: <https://trac.torproject.org/projects/tor/ticket/21493#comment:3>
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