I know most onion directories use crawlers to collect onion addresses.

If I never share my onion address publicly or with anyone, can onion directories still find ways of discovering the address?

EDIT: And if directories can locate my onion address, can they also discover the port number it's listening on (eg. mysuperlameonion.onion:43155)?

  • i'm not sure how discovery of onion-addresses is done, but if your address is known, the port is no problem: a simple port scan and that's it. Mar 5, 2019 at 10:56
  • hopefully you're asking this out of curiosity resp. for research purposes and not because you want to "hide" your server?! - this would be "Security through obscurity" which is considered to be really bad practice, rather follow "Kerckhoffs's principle" which will provide real security. Mar 5, 2019 at 11:03
  • ...or simply have a "predecessor" of "Murphy's law" in mind: whatever can happen will happen. Mar 5, 2019 at 11:11
  • regarding that (although i don't know exactly how it is done technically - hence no answer) i would say: yes, your server and port can be found, and sooner or later it will be found. Mar 5, 2019 at 11:17

1 Answer 1


As far as I know, only Hidden Service Directories knows the rendezvous point and public key of your hidden service, which they can obtain Onion address from your public key.

However, if you never publish your onion address, no one can find your address unless they use bruteforce search over onion addresses.

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