Robert L. Ziegler has written a nifty tool for creating a
firewall with Linux, completely accessed online through a web
browser.
The home version of the Linux IPFW Firewall Design Tool is a
web-based tool that lets you custom-configure a packet-filtering
firewall script for your home system, including a home LAN with IP
address masquerading on the internet.
The interface is designed to be simple, clear, and yet flexible
enough for an average home setup.
The default settings will meet the needs of many or most home
Linux users.
The firewall is based on a bi-directional “deny by default”
firewall policy to provide stronger security than can conveniently
be provided by hand.
Default safe-guards are built-in for the occasional home
environment where internal security is a concern. Since this is a
shell script and the firewall rules are commented, the safe-guards
can easily be disabled by the root user if they are too
restrictive. Additional, optional, selective port access by
client-server pairs allow further protection
With the use of an optional configuration file, external sites
can be denied access completely or by service, or allowed port
access selectively in a more limited fashion than the general site
configuration.
A commercial version that contains extra features also
exists.