KickstartCassiopeia enables you to filter access to your site.

For instance, you want to use your website as an intranet, and only have certain people have access, based on IP numbers. KickstartCassiopeia allows you to simple add these IP numbers to a whitelist, and limit access to only those numbers. In order to do this, go to your module, tab IP. Enable the option, and set ip's that only have access to your site. You can even set an offline-message: