Mysql：Changes in MySQL 5.6.30 (2016-04-11, General Availability)：--ssl-mode：

In MySQL 5.7 and higher, the C client library provides native support for requiring encrypted connections: call the mysql_options() C API function, passing the MYSQL_OPT_SSL_MODE option with a value of SSL_MODE_REQUIRED. In MySQL 5.6, the client library provides no such support because doing so would break binary compatibility with previous library versions within the series. Clients that require encrypted connections must implement the logic themselves.

To require encrypted connections in MySQL 5.6, the standard MySQL client programs use this technique: If --ssl-mode=REQUIRED was specified, the client program turns on SSL, connects to the server, and checks whether the resulting connection is encrypted. If not, the client exits with an error. Third-party applications that must be able to require encrypted connections can use the same technique. For details, see mysql_ssl_set().