Enumerates a TLS server's supported protocols by using the next protocol negotiation extension.
This works by adding the next protocol negotiation extension in the client hello packet and parsing the returned server hello's NPN extension data.
For more information, see:
nmap --script=tls-nextprotoneg <targets>
443/tcp open https | tls-nextprotoneg: | spdy/3 | spdy/2 |_ http/1.1
Author: Hani Benhabiles
License: Same as Nmap--See https://nmap.org/book/man-legal.html