How to detect if a server is using SPDY

Question

Any way to detect if a remote website supports SPDY and what version it is?

Something I can use from the command line like a bash script.

Tried sending custom User-Agent headers with curl but can't get any kind of response headers that would help me.

The idea is to be able to get SPDY:true/false Version:3.1/3.0... for any domain.

Answer 1

openssl s_client -connect google.com:443 -nextprotoneg ''
CONNECTED(00000003)
Protocols advertised by server: spdy/3.1, spdy/3, http/1.1