5.9 Tutorial: Using SSL with MySQL Connector/Net

In this tutorial you will learn how you can use MySQL Connector/Net to connect to a MySQL server configured to use SSL. Support for SSL client certificates was added with MySQL Connector/Net 6.2.

MySQL Server uses the PEM format for certificates and private keys. This tutorial will use the test certificates from the server test suite by way of example. You can obtain the MySQL Server source code from MySQL Downloads. The certificates can be found in the directory ./mysql-test/std_data.

To carry out the steps in this tutorial, you must have Open SSL installed. This can be downloaded for Microsoft Windows at no charge from Shining Light Productions.

Further details on the connection string options used in this tutorial can be found at Chapter 7, Connector/Net Connection String Options Reference.

Configuring the MySQL Server to use SSL

  1. In the MySQL Server configuration file, set the SSL parameters as follows:

    ssl-ca=path/to/repo/mysql-test/std_data/cacert.pem 
    ssl-cert=path/to/repo/mysql-test/std_data/server-cert.pem 
    ssl-key=path/to/repo/mysql-test/std_data/server-key.pem 
    

    Adjust the directories according to the location in which you installed the MySQL source code.

  2. In this step you create a test user and set the user to require SSL.

    Using the MySQL Command-Line Client, connect as root and create the user sslclient.

  3. To set privileges and requirements, issue the following command:

    GRANT ALL PRIVILEGES ON *.* TO sslclient@'%' REQUIRE SSL;
    

Creating a certificate file to use with the .NET client

  1. The .NET client does not use the PEM file format, as .NET does not support this format natively. You will be using test client certificates from the same server repository, for the purposes of this example. Convert these to PFX format first. This format is also known as PKCS#12. An article describing this procedure can be found at the Citrix website. From the directory server-repository-root/mysql-test/std_data, issue the following command:

    openssl pkcs12 -export -in client-cert.pem -inkey client-key.pem -certfile cacert.pem -out client.pfx
    
  2. When asked for an export password, enter the password pass. The file client.pfx will be generated. This file is used in the remainder of the tutorial.

Connecting to the server using a file-based certificate

  1. You will use PFX file, client.pfx you created in the previous step to authenticate the client. The following example demonstrates how to connect using the SSL Mode, CertificateFile and CertificatePassword connection string options:

    using (MySqlConnection connection = new MySqlConnection( 
      "database=test;user=sslclient;" +  
      "CertificateFile=H:\\bzr\\mysql-trunk\\mysql-test\\std_data\\client.pfx" +  
      "CertificatePassword=pass;" + 
      "SSL Mode=Required ")) 
    { 
        connection.Open(); 
    }
    

    The path to the certificate file will need to be changed to reflect your individual installation.

Connecting to the server using a store-based certificate

  1. The first step is to import the PFX file, client.pfx, into the Personal Store. Double-click the file in Windows explorer. This launches the Certificate Import Wizard.

  2. Follow the steps dictated by the wizard, and when prompted for the password for the PFX file, enter pass.

  3. Click Finish to close the wizard and import the certificate into the personal store.

Examine certificates in the Personal Store

  1. Start the Microsoft Management Console by entering mmc.exe at a command prompt.

  2. Select File, Add/Remove snap-in. Click Add. Select Certificates from the list of available snap-ins in the dialog.

  3. Click Add button in the dialog, and select the My user account radio button. This is used for personal certificates.

  4. Click the Finish button.

  5. Click OK to close the Add/Remove Snap-in dialog.

  6. You will now have Certificates – Current User displayed in the left panel of the Microsoft Management Console. Expand the Certificates - Current User tree item and select Personal, Certificates. The right-hand panel will display a certificate issued to MySQL. This is the certificate that was previously imported. Double-click the certificate to display its details.

  7. After you have imported the certificate to the Personal Store, you can use a more succint connection string to connect to the database, as illustrated by the following code:

    using (MySqlConnection connection = new MySqlConnection( 
       "database=test;user=sslclient;" +  
       "Certificate Store Location=CurrentUser;" +  
       "SSL Mode=Required")) 
    { 
       connection.Open(); 
    }
    

Certificate Thumbprint Parameter

If you have a large number of certificates in your store, and many have the same Issuer, this can be a source of confusion and result in the wrong certificate being used. To alleviate this situation, there is an optional Certificate Thumbprint parameter that can additionally be specified as part of the connection string. As mentioned before, you can double-click a certificate in the Microsoft Management Console to display the certificate's details. When the Certificate dialog is displayed click the Details tab and scroll down to see the thumbprint. The thumbprint will typically be a number such as ‎47 94 36 00 9a 40 f3 01 7a 14 5c f8 47 9e 76 94 d7 aa de f0. This thumbprint can be used in the connection string, as the following code illustrates:

using (MySqlConnection connection = new MySqlConnection( 
      "database=test;user=sslclient;" + 
      "Certificate Store Location=CurrentUser;" + 
      "Certificate Thumbprint=479436009a40f3017a145cf8479e7694d7aadef0;"+ 
      "SSL Mode=Required")) 
{ 
    connection.Open(); 
}

Spaces in the thumbprint parameter are optional and the value is case-insensitive.