Support TLSv1.1 and TLSv1.2 for the cluster transport encryption
From https://wiki.openssl.org/index.php/SSL/TLS_Client:
SSLv23_method specifies the protocols used and behavior of the handshake.
The method essentially means SSLv2 or above, and includes the TLS protocols.
The protocols are further tuned through SSL/TLS options. By using
SSLv23_method (and removing the SSL protocols with SSL_OP_NO_SSLv2 and
SSL_OP_NO_SSLv3), then you will use TLS v1.0 and above, including TLS v1.2.
You will also use a TLS handshake in the TLS Record.
If you use TLSv1_method, then you will only use TLS v1.0.