6.4.1 Configuring MySQL to Use Encrypted Connections

To enable encrypted connections, your MySQL distribution must be built with SSL support, as described in Section 6.4.5, “Building MySQL with Support for Encrypted Connections”. In addition, several options are available to indicate whether to use encrypted connections, and to specify the appropriate certificate and key files. This section provides general guidance about configuring the server and clients for encrypted connections:

• Server-Side Configuration for Encrypted Connections

• Client-Side Configuration for Encrypted Connections

For a complete list of options related to establishment of encrypted connections, see Section 6.4.2, “Command Options for Encrypted Connections”. If you need to create the required certificate and key files, see Section 6.4.3, “Creating SSL and RSA Certificates and Keys”.

Encrypted connections can be used between master and slave replication servers. See Section 17.3.8, “Setting Up Replication to Use Encrypted Connections”.

Encrypted connections are available through the MySQL C API. See Section 23.8.15, “C API Encrypted Connection Support”.

Server-Side Configuration for Encrypted Connections

These options on the server side identify the certificate and key files the server uses when permitting clients to establish encrypted connections:

• --ssl-ca identifies the Certificate Authority (CA) certificate.

• --ssl-cert identifies the server public key certificate. This can be sent to the client and authenticated against the CA certificate that it has.

• --ssl-key identifies the server private key.

For example, to enable the server for encrypted connections, start it with these lines in the my.cnf file, changing the file names as necessary:

[mysqld]
ssl-ca=ca.pem
ssl-cert=server-cert.pem
ssl-key=server-key.pem

Each option names a file in PEM format. If you have a MySQL source distribution, you can test your setup using the demonstration certificate and key files in its mysql-test/std_data directory.

Client-Side Configuration for Encrypted Connections

These options on the client side identify the certificate and key files clients use when establishing encrypted connections to the server. They are similar to the options used on the server side, but --ssl-cert and --ssl-key identify the client public and private key:

• --ssl-ca identifies the Certificate Authority (CA) certificate. This option, if used, must specify the same certificate used by the server.

• --ssl-cert identifies the client public key certificate.

• --ssl-key identifies the client private key.

Depending on the encryption requirements of the MySQL account used by a client, the client may be required to specify certain options to connect using encryption to a MySQL server that supports encrypted connections.

Suppose that you want to connect using an account that has no special encryption requirements or was created using a GRANT statement that includes the REQUIRE SSL option. As a recommended set of encrypted-connection options, start the server with at least --ssl-cert and --ssl-key, and invoke the client with --ssl-ca. A client can connect using encryption like this:

mysql --ssl-ca=ca.pem

To require that a client certificate also be specified, create the account using the REQUIRE X509 option. Then the client must also specify the proper client key and certificate files or the server will reject the connection:

mysql --ssl-ca=ca.pem \
      --ssl-cert=client-cert.pem \
      --ssl-key=client-key.pem

For additional information about the REQUIRE clause, see the discussion in Section 13.7.1.4, “GRANT Syntax”.

To prevent use of encryption and override other --ssl-xxx options, invoke the client program with --ssl=0 or a synonym (--skip-ssl, --disable-ssl):

mysql --ssl=0

To determine whether the current connection with the server uses encryption, check the value of the Ssl_cipher status variable. If the value is empty, the connection is not encrypted. Otherwise, the connection is encrypted and the value indicates the encryption cipher. For example:

mysql> SHOW SESSION STATUS LIKE 'Ssl_cipher';
+---------------+--------------------+
| Variable_name | Value              |
+---------------+--------------------+
| Ssl_cipher    | DHE-RSA-AES256-SHA |
+---------------+--------------------+

For the mysql client, an alternative is to use the STATUS or \s command and check the SSL line:

mysql> \s
...
SSL: Not in use
...

Or:

mysql> \s
...
SSL: Cipher in use is DHE-RSA-AES256-SHA
...