Encryption is missing

[wonderix]

It's not possible to open TLS encrypted connections

[stakach]

Looking at this article you need to start SSL after the connection is established.
https://www.datasunrise.com/blog/professional-info/encryption-in-microsoft-sql-server/

LDAP works in a similar way, this is an example of negotiating SSL / TLS on an exising connection
(the last line of this function)
https://github.com/spider-gazelle/crystal-ldap/blob/master/src/ldap/client.cr#L127-L139

Hope that helps

[wonderix]

Thanks for this link. It really explains the handshake quite well. It's easier to understand compared to studying the freetds code.