With the old v2 hidden services (16 character long onion addresses) it was possible to recover the onion addresses of any service running on the Tor network while the v2 hidden service was running.
However, that issue was only present in v2 hidden services. v2 has been depreciated in favor of the new v3 hidden service protocol (56 character long onion addresses) which is not vulnerable to this issue. This new protocol contains a full ed2559 elliptic curve public key in the onion address. The key in the onion address is used to derive what are called "blind keys". These "blinded keys" are then announced to the Tor network in such a way that nobody can recover the original public key without prior knowledge of the it, leaving them unable to establish a connection with the hidden service.
I have only briefly elaborated on how v3 hidden services work. If you are interested in a more in depth and technical explanation I encourage you to read:
This is incorrect. A Tor hidden service is fundamentally different from port forwarding. If you don't have the hidden services onion address (v3 address) then you physically cannot make a connection to the hidden service. This is because the onion address is the hidden services public key.
You can scan the entire internet for open ports, you can't scan the Tor network for hidden services to connect to unless you already have the hidden services onion addresses.
This is completely incorrect. It is physically impossible to make a connection to a hidden service without the hidden services onion address (I am talking about the current v3 onion addresses, the ones that are 56 characters long). This is thanks to the fact that the onion address itself is the hidden services public key.
If you keep your onion address private then nobody can connect to your hidden service or even know that it exists. Simple as that.
This makes me think of Whoopi Goldberg's introduction to the second volume of the "Tom and Jerry Spotlight Collection" published in 2005 [0]. Warner Bros faced the same kind question that we see these companies grappling with now and decided it was best to keep a majority of the offensive content in the collection. Most importantly, the collection was prefaced by Whoopi Goldberg and she explained why the offensive clips were included. I highly recommend anyone who reads this comment to watch the video below.
I personally feel as though it would be better to do something like this with Dr. Seuss' books rather than ceasing their publication.
However, that issue was only present in v2 hidden services. v2 has been depreciated in favor of the new v3 hidden service protocol (56 character long onion addresses) which is not vulnerable to this issue. This new protocol contains a full ed2559 elliptic curve public key in the onion address. The key in the onion address is used to derive what are called "blind keys". These "blinded keys" are then announced to the Tor network in such a way that nobody can recover the original public key without prior knowledge of the it, leaving them unable to establish a connection with the hidden service.
I have only briefly elaborated on how v3 hidden services work. If you are interested in a more in depth and technical explanation I encourage you to read:
[0] - https://gitweb.torproject.org/torspec.git/tree/rend-spec-v3.... [1] - https://gitlab.torproject.org/legacy/trac/-/wikis/doc/NextGe...