\section{Preface}
\subsection{Summary}
In this paper a general overview of firewalling is presented, and some
basic terms used in the Linux firewall implementation is given. Based
on requirements of a firewall, a design is presented which will ease
the setup of a firewall. The resulting implementation is briefly
described and configuration is explaind in detail.

\subsection{Prerequisites}
In this paper, it is assumed that the reader is familiar with network
theory, routing and network traffic. Basic Linux knowledge is
preferable in order to setup the software described in this paper,
though not a requirement.







