If you wish to only allow specific addresses to access an app, you can add the following to your app's .htaccess file:
<RequireAny> Require ip 1.2.3.4 Require ip 23.34.45.56 </RequireAny>
Be sure to replace 1.2.3.4 and 23.34.45.56 with the IP addresses you want to allow.
Apache also offers more information on configuring access control from your app's .htaccess file.