Say you have a nasty application on your Apache webserver that has been installed by some people from the marketing department and you can neither remove nor patch it. Maybe it is a time problem, a lack of know-how, a lack of source-code, or possibly even political reasons. Consequently you need to protect it without touching it. There is ModSecurity, but they say this is only for experts. A straightforward alternative is Remo, a graphical rule editor for ModSecurity that comes with a whitelist approach. It has all you need to lock down the application.