How To Check A Site For SPDY Support With OpenSSL

A Stack Overflow thread with an example on how to check a server for SPDY support with OpenSSL:

openssl s_client -connect google.com:443 -nextprotoneg ''

The result I got from “OpenSSL 1.0.1f 6 Jan 2014” looked like this ( emphasis mine ):

CONNECTED(00000003)
Protocols advertised by server: spdy/5a1, h2-14, spdy/3.1, spdy/3, http/1.1
139790806673056:error:140920E3:SSL routines:SSL3_GET_SERVER_HELLO:parse tlsext:s3_clnt.c:1061:
---
no peer certificate available
---
No client certificate CA names sent
---
SSL handshake has read 110 bytes and written 7 bytes
---
New, (NONE), Cipher is (NONE)
Secure Renegotiation IS supported
Compression: NONE
Expansion: NONE
Next protocol: (2) 
SSL-Session:
    Protocol  : TLSv1.2
    Cipher    : 0000
    Session-ID: 
    Session-ID-ctx: 
    Master-Key: 
    Key-Arg   : None
    PSK identity: None
    PSK identity hint: None
    SRP username: None
    Start Time: 1417496091
    Timeout   : 300 (sec)
    Verify return code: 0 (ok)
---

The “Protocols advertised by server:” is the line you need.