Step 1: Copy the Certificate files to your server.
Download your intermediate certificate, then copy it to the directory on your server where you will keep your certificate and key files. Make them readable by the root only.
Step 2: Find the Apache config file to edit.
The location and name of this file can vary from server to server -- especially if you use a special interface to manage your server configuration.
Apache configuration files are typically found in /etc/httpd. The main configuration file is usually named httpd.conf. In some cases, the <VirtualHost> blocks will be at the bottom of this httpd.conf file. Sometimes you will find the <VirtualHost> blocks in their files under a directory like /etc/httpd/vhosts.d/ or /etc/httpd/sites/ or in a file called ssl.conf.
If you open the file with a text editor, you should be able to find <VirtualHost> blocks that contain Apache settings.
Step 3: Identify the SSL <VirtualHost> block to configure.
If you need your site to be accessible through both secure (https) and non-secure (http) connections, you will need a virtual host for each type of connection. Make a copy of the existing non-secure virtual host and configure it for SSL as described in step 4.
If you only need your site to be accessed securely, configure the existing virtual host for SSL as described in step 4.
Step 4: Overwrite the DigiCertCA.crt file with the new DigiCert Intermediate.
Overwrite your existing DigiCertCA.crt file on your server with your new DigiCert intermediate certificate by naming your new DigiCertCA.crt.crt file with the same name as your current SSLCertificateChainFile certificate name.
If you overwrite the DigiCertCA.crt file, you can restart your Apache server, and the new DigiCert intermediate certificate will automatically be used.
Below is a very simple example of a virtual host configured for SSL. The parts listed in bold are the parts that must be added for SSL configuration:
DocumentRoot /var/www/html2
ServerName www.yourdomain.com
SSLEngine on
SSLCertificateFile /path/to/your_domain_name.crt
SSLCertificateKeyFile /path/to/your_private.key
SSLCertificateChainFile /path/to/DigiCertCA.crt
Step 5: Restart Apache.
You can use apachectl commands to stop and start Apache with SSL support:
apachectl stop
apachectl start