GnuTLS server support?

[Qiantan Hong]

It seems that currently Emacs can act as a TLS client,
not a server. 
This makes it impossible to have secure connection between Emacsen.

Anyone have an idea how much effort will make it works?

Or alternatively, I could outsource it to external gnutls-serv.
It feels going backward in time though, to my understanding
that is the obsolete implementation strategy 
Emacs used to use (using gnutls-cli though).
Do you now recommend against such strategy?

Best,
Qiantan