Hi, now that I’ve almost done with other part I’m
looking back into this connectivity problem.

I mentioned the idea of messaging over IRC, however
after thinking a bit more on that approach, seems that
IRC has no reliability guarantee and I’ll have to implement
tcp-over-irc.el … that already seems like much more work
than expected.

ICE/STUN looks like the usual way to do the NAT traversal,
however I didn’t find any tcp tunnel over ICE/STUN that
I can use directly in Emacs. Does any one know any?

There’s libnice but it’s a C library, we’ll either have to
write more Emacs C code to use it or wrap it in a cli tool
providing tcp tunneling...

> On Sep 29, 2020, at 12:29 PM, Stefan Monnier <monnier@iro.umontreal.ca> wrote:
> 
>>> 1) On one hand such services require some servers (to work like google
>>> spreadsheet) and need to be provided somehow... something difficult as I
>>> don't think gnu or fsf have resources to maintain a service like that
>>> and provide it.
>> CRDT should do it.
> 
> I think CRDT make no difference to the problem referred to here, which
> is that two machines, each behind its own firewall will have difficulty
> talking to each other unless they go through some external server (at
> least to set up the initial connection).  There are *partial* solutions in
> the form of ICE/STUN.
> 
> 
>        Stefan
>