Oct 23, 2014
How to verify if TLS 1.2 is supported on a remote web server from shell.
Occasionally, it's helpful to know if a remote web server supports TLS 1.2. That can be done a couple ways...
Option 1 - You can check with openssl (versions 1.0.0h+ and 1.0.1+):
openssl s_client -connect examplewebserver.com:443 -tls1_2
The -tls1_2 option forces openssl to use TLS 1.2. So if you can't connect or get a handshake failure with that specific option, the remote server doesn't support it.
Option 2 - You can run nmap to get a list of the supported ciphers:
nmap --script ssl-enum-ciphers -p 443 examplewebserver.com
Among the output there should be a section describing TLSv1.2 ciphers.
Thanks to the fine folks at serverfault for help!