[tor-bugs] #8215 [Tor]: Simple Relay: random unknown UDP port in listen mode

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#8215: Simple Relay: random unknown UDP port in listen mode
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     Reporter:  elgo         |      Owner:
         Type:  enhancement  |     Status:  reopened
     Priority:  normal       |  Milestone:  Tor: unspecified
    Component:  Tor          |    Version:
   Resolution:               |   Keywords:  tor-relay dns
Actual Points:               |  Parent ID:
       Points:               |
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Changes (by cypherpunks):

 * keywords:  tor-relay => tor-relay dns


Comment:

 This raises four questions for me:

  - Why does Tor do its own DNS lookups, instead of using the system's
 resolver?

  - Why does a Tor relay need to do DNS lookups at all?

  - If Tor actually needs to do its own DNS lookups, shouldn't it be using
 a randomized source port for every query? (Otherwise it is relatively
 trivial to send it spoofed answers, no?)

  - Is it bad that my Tor relay where I just noticed this port (leading me
 to find this ticket) can only make TCP connections? It seems to be
 relaying traffic nonetheless, but now I'm worried perhaps I'm failing
 circuits to relays which only have DNS names in their descriptors? (Do
 such relays exist?)

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Ticket URL: <https://trac.torproject.org/projects/tor/ticket/8215#comment:10>
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