mysql> show variables like "%ssl%";
+---------------+--------------------------------------+
| Variable_name | Value                                |
+---------------+--------------------------------------+
| have_openssl  | YES                                  |
| have_ssl      | YES                                  |
| ssl_ca        | /etc/mysql/ssl-mysql/ca-cert.pem      |
| ssl_capath    |                                      |
| ssl_cert      | /etc/mysql/ssl-mysql/server-cert.pem |
| ssl_cipher    |                                      |
| ssl_key       | /etc/mysql/ssl-mysql/server-key.pem  |
+---------------+--------------------------------------+

$ mysql -h 1.2.3.4 --ssl-ca=/etc/mysql/ssl-mysql/ca-cert.pem --ssl-cert=/etc/mysql/ssl-mysql/client-cert.pem --ssl-key=/etc/mysql/ssl-mysql/client-key.pem -u root -p
Enter password:
ERROR 2026 (HY000): SSL connection error

SSL error: Unable to get certificate from '/etc/mysql/ssl-mysql/client-cert.pem'
[ERROR] Slave I/O: error connecting to master 'replica@1.2.3.4:3306' - retry-time: 60  retries: 1, Error_code:2026

mysql -h 1.2.3.4 --ssl-ca=/etc/mysql/ssl-mysql/ca-cert.pem -u replica -p

mysql> s
--------------
mysql  Ver 14.14 Distrib 5.6.27, for Linux (x86_64) using  EditLine wrapper

Connection id:      6873
Current database:
Current user:       replica@1.2.3.5
SSL:            Cipher in use is DHE-RSA-AES256-SHA