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.