How to use SSL in PHP Data Objects (PDO) mysql

Here is the code snippet to set PDO properties for your SSL/TLS secured connection to MySQL.

<?php
$servername = "db_hostname";
$username = "db_username";
$password = "db_password";
$options = array(
  PDO::MYSQL_ATTR_INIT_COMMAND => 'SET NAMES utf8',
  PDO::MYSQL_ATTR_SSL_CA => '/path/to/cacert.pem',
  PDO::MYSQL_ATTR_SSL_VERIFY_SERVER_CERT => false,
);

try {
    $conn = new PDO("mysql:host=$servername;port=3306;dbname=db_name", $username, $password, $options);
    // set the PDO error mode to exception
    $conn->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
    echo "Connected successfully"; 
        var_dump($conn->query("SHOW STATUS LIKE 'Ssl_cipher';")->fetchAll());
        $conn = null;
}
catch(PDOException $e)
    {
    echo "Connection failed: " . $e->getMessage();
}
?>

Please note that the above code should only work correctly on Windows Server, due to path to cacert.pem. See below. The PDO option MYSQL_ATTR_SSL_VERIFY_SERVER_CERT is important to disable checking of the server certificate. If omitted, you'll receive an error: `SQLSTATE[HY000] [2002]`.

Cross-platform MYSQL_ATTR_SSL_CA usage in PHP

As you may know, in your Windows Server IIS PHP config, you need to set an [openssl.cafile](/posts/dont-turn-off-curlopt_ssl_verifypeer-fix-php-configuration/) directive, providing the path to a Certificate Authority (CA) file. This is not necessary on Linux, where the system default is used. MYSQL_ATTR_SSL_CA needs this path on Windows, and may be omitted on Linux.

To add this logic into your PDO test script, add an extra variable with your OS information and change the MYSQL_ATTR_SSL_CA line:

$OS = ( strtoupper( substr( PHP_OS, 0, 3 ) ) === 'WIN' );
PDO::MYSQL_ATTR_SSL_CA => $OS ? 'c:/path/to/cacert.pem' : '',

Your $options array becomes:

$OS = ( strtoupper( substr( PHP_OS, 0, 3 ) ) === 'WIN' );

$options = array(
  PDO::MYSQL_ATTR_INIT_COMMAND => 'SET NAMES utf8',
  PDO::MYSQL_ATTR_SSL_CA => $OS ? 'c:/path/to/cacert.pem' : '',
  PDO::MYSQL_ATTR_SSL_VERIFY_SERVER_CERT => false,
);

If $OS === true (e.g $OS === 'WIN') use c:/path/to/cacert.pem as PDO::MYSQL_ATTR_SSL_CA file path, else we're on Linux and omit the path. This way you are sure you can use this PHP code cross-platform on both Windows Server and Linux!

Secure MySQL connections in WordPress with SSL/TLS

In WordPress you can define a MYSQL_CLIENT_FLAGS constant with MYSQLI_CLIENT_SSL as its value. This makes WordPress make SSL/TLS secured connections to your MySQL database.

Add to your WordPress wp-config.php file:

define( 'MYSQL_CLIENT_FLAGS', MYSQLI_CLIENT_SSL );