[tor-talk] What is "a.onion"?

[Gisle Vanem]

Trying the C-ares [1] program adig on some .onion addresses
on my local Tor/Windows, I get responses like (short output):

c:\> adig -t A a.onion
Answers:
a.onion . 60 A 127.247.163.198

Or c:\> adig -t A b.onion
Answers:
b.onion . 60 A 127.207.1.12

-----

What are these 127.a.b.c.d addresses and their relations to
'a' and 'b'?

[1] https://github.com/c-ares/c-ares/

[Rusty Bird]

Post by Gisle Vanem
Trying the C-ares [1] program adig on some .onion addresses
c:\> adig -t A a.onion
a.onion . 60 A 127.247.163.198
Or c:\> adig -t A b.onion
b.onion . 60 A 127.207.1.12
-----
What are these 127.a.b.c.d addresses and their relations to
'a' and 'b'?

Your tor daemon picks these .onion <-> IP address associations at
random. They're only valid for your local tor daemon instance, and
only until it is restarted. The IPv4 address range is controlled by
the VirtualAddrNetworkIPv4 option:

https://www.torproject.org/docs/tor-manual.html.en#VirtualAddrNetworkIPv4

It can be used for transparent torification:

https://trac.torproject.org/projects/tor/wiki/doc/TransparentProxy

Rusty