OpenSSL SNI documentation

[hannesfostie]

We had an issue where we had to figure out a way to make the following command work through Ruby's stdlib:

echo | openssl s_client -connect google.com:443 -servername google.com 2>/dev/null | openssl x509 -noout -fingerprint

Note the -servername option

I spent a lot of time looking around, first looking at the servername_cb callback (which in itself is poorly documented if at all), only later realizing there's a hostname attribute on OpenSSL::SSL::SSLContext

In case you're not familiar with the servername option, it's used to get the correct certificate on a domain name where the host uses Server Name Indication or SNI in short.

[zzak]

@hannesfostie Thanks for the report!

[zzak]

@hannesfostie Sorry I haven't had time to get to this, would this be something you'd be interested in helping out with?

[hannesfostie]

@zzak I'm afraid I know far too little about all this to be able to pull that off