\section{Related work}
Many tools exists to help setup a firewall, and create the rules
necessary for Linux.  In general, these tools can be categorized into
two major categories:

\begin{description}
\item[Specific tools:] Many firewall scripts help the user to setup a
  firewall for a special purpose. These tools contain no or very
  little level of configuration, as they are made with a simple
  purpose in mind. Examples are scripts that sets up a masquerading
  firewall with only one internal network. Configuration is mainly done
  by changing in the source code (usually accompanied with good
  comments of where and what to change). These scripts are usually
  targeted for the mass public, where a firewall protects a single home
  LAN from attacks from the Internet. 

\item[Generic tools:] Tools that are extensible and not limited to
  a specific network setup fall into this category. Setup is usually
  done with no modifications to the source code, and users are
  required to have extensive knowledge of network setup and security
  issues.

\end{description}
Hundreds of scripts that fall into the \textit{specific tools}
exists, while only very few are generic tools. Of these can be named:

\begin{description}
\item[Shorewall:] Shorewall\cite{shorewall} seems to be the most attractive alternative
  to FIAIF. The term zones are also used in this
  product. Configuration is said the be somewhat more difficult than
  FIAIF, and configuration is not split into zone configuration files.
  
\item[Mandrake: Multi Network Firewall:] This commercial firewall\cite{mnf}
  supports definitions of multiple security zones, support for virtual
  private networks (VPN), configurable through a web interface. The
  product is commercial, and costs in the area of \$2000. As
  Mandrakesoft has filed for bankruptcy, the stability in using this
  commercial firewall is somewhat questionable.

\end{description}





 
