Abstract
Firewalls are crucial for the security of most networks and implemented by packet filters. Those packet filters can be considered the direct opposite of a simple-to-use system. Configured with complex commands in plain text files, only experts are able to understand or even modify such a setup. Recently, this process has been improved by using a combination of external tools, a graphical modeling environment, and a model checker, enabling more users to participate in the process and clearing the way to automatic testing. This paper revists this concept from a simplicity perspective and shows how the whole process can be simplified while simultaneously the level of abstraction is increased and new ways of verifying the result are possible.