[tor-bugs] #17605 [Tor]: Tell caches to remove X-Your-IP-Address-Is from Tor Directory documents

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#17605: Tell caches to remove X-Your-IP-Address-Is from Tor Directory documents
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 Reporter:  teor      |          Owner:
     Type:  defect    |         Status:  new
 Priority:  High      |      Milestone:  Tor: 0.2.8.x-final
Component:  Tor       |        Version:
 Severity:  Normal    |     Resolution:
 Keywords:  tor-auth  |  Actual Points:
Parent ID:            |         Points:
  Sponsor:            |
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Comment (by arma):

 What if we went a step further and didn't include the header at all in
 unencrypted connections? That is, we include it in the begin_dir response
 but not in the naked dirport responses.

 The main effect would be that relays, who use the naked dirport, would no
 longer be able to learn their IP address from their directory authority
 interactions.

 We could work around that by finally moving all dir traffic to begin_dir
 (which still makes me uncomfortable because of the extra scaling and load,
 but maybe this is a good additional kick for why we should do it anyway),
 or by having relays who don't know their address launch a begin_dir
 connection just for finding it out.

 Actually, wait a minute, don't netinfo cells have your address in them now
 too? Does that mean x-your-address-is on naked dirport answers is
 redundant? And thus we should try to phase it out in favor of the
 encrypted, authenticated mechanism that we built?

 The reason I want to get rid of the caching situation is because this is
 an information leak, from one user to another. Now, it's mostly just
 relays who suffer, since they're the ones who use naked dirport requests.
 But this is still an uncomfortable state of affairs to leave in place.

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Ticket URL: <https://trac.torproject.org/projects/tor/ticket/17605#comment:4>
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