[tor-onions] Retrieving a list of connections to own hidden service

[Taylor R Campbell]

> Date: Thu, 24 Sep 2020 12:46:13 +0200
> From: Vasil Dimov <vd at freebsd.org>
> 
> Which creates a hidden service addrwhatever.onion. Later somebody
> connects to addrwhatever.onion:8333 and the tor daemon opens a TCP
> connection like 127.0.0.1:46153 -> 127.0.0.1:8333. Next, some other
> application (not the tor daemon) connects directly to 127.0.0.1:8333
> and that is 127.0.0.1:52490 -> 127.0.0.1:8333.
> 
> What if the application running at 127.0.0.1:8333 wants to distinguish
> incoming tor connections from the rest? From its point of view the
> connections from the example above are just TCP connections coming from
> 127.0.0.1:46153 and 127.0.0.1:52490.

Can you just use two different sockets, one for connections via Tor
and one for non-Tor connections?  Then you won't have to go to the
trouble of communicating with the tor daemon, worrying about race
conditions, &c.

You can use local sockets instead of IP sockets too -- just do:

ADD_ONION <secretkey> Port:8333,unix:/var/service/torsocket

to make the tor daemon connect to /var/service/torsocket instead of
127:0.0.1:8333.  Then you can use ordinary file system permissions to
control access to it so nobody other than the tor daemon can connect
to that socket.

This is the mechanism that my ucspi-onion tool uses:

https://mumble.net/~campbell/hg/ucspi-onion