[tor-relays] What are the v1, v2, v3, v4 connections?

[Roger Dingledine]

On Tue, May 17, 2016 at 08:25:33PM -0400, William Denton wrote:
> "Since startup, we have initiated 0 v1 connections, 1 v2
> connections, 0 v3 connections, and 12345 v4 connections."
> 
> What are these different types of connections?  I can't find them in
> the docs, so I assume I'm not looking in the right place.  (And what
> does it mean that the 1 v2 connection sneaked in?)

See
https://gitweb.torproject.org/torspec.git/tree/tor-spec.txt#n467
and
https://gitweb.torproject.org/torspec.git/tree/tor-spec.txt#n535

I wouldn't worry about the 1 v2 connection. I can imagine a variety of
harmless scenarios that could cause it. I admit to some curiosity too,
but life is too short as it is. :)

--Roger