I am working on setting up a Tor obfs4 bridge. If I understand it correctly ServerTransportListenAddr allows me to choose a port (and an IP) to bind the Pluggable Transport to. However I also need to set an ORPort and Tor logs that it does reachability tests.

Doesn't this defeat the whole point of using a pluggable transport and obfs4 in particular? Couldn't an attacker just look for the normal ORPort and thereby detect the bridge as such?

Do I need to forward the ORPort?

1 Answer 1


The attacker wouldn't be able to find you if nobody tries to connect to your ORPort. If you didn't publish the bridge descriptor, nobody will know your ORPort.

  • But then there are a few open questions: Why not randomize it and why does it have to be open then (having reachability tests)?
    – meee
    Oct 18, 2014 at 17:37
  • It can be random (just input random number) and even unreachable. Even if reachability test fails, your bridge will still run well.
    – nobody
    Oct 19, 2014 at 1:41
  • Okay, thank you. And it will still be propagated to bridge authorities?
    – meee
    Oct 19, 2014 at 10:05
  • It looks like there is a ticket for this
    – meee
    Oct 19, 2014 at 11:06

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