There is a nice howto available, which explains how to install a SSL-certificate within ISPConfig for a website. http://www.howtoforge.com/faq/14_49_en.html I took all the steps with ISPConfig 2.2.15 and everything works perfectly, except one thing at the end. When the official SSL-certificate has been saved within the SSL-field, ISPConfig does not restart Apache2. Restarting Apache2 is necesarry, otherwise the certicate is not trusted when you visit the https:// website. For this reason i suggest to add the line: "Restart Apache2 afterwards with: etc/init.d/apache2 restart". It would be more nice if ISPConfig restarts Apache2 after saving the SSL-certificate automaticly.