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Running a Linux Firewall/Router 18
Getting iptables Scripts
Rather than type in all your firewall rules by hand, many scripts are available on the Internet
(licensed under the GPL) that you can modify to suit your needs. Many of these scripts contain
sections in the front where you can add IP addresses, port numbers, and other information that
is specific to your firewall setup.
A nice set of scripts that illustrate how to use iptables comes from Oskar Andreasson, the author
of the iptables tutorial. The set can be found at http://iptables-tutorial.frozentux.net/
scripts/. In particular, rc.firewall.txt is a good file to step through.
Finding Out More About iptables
So far, you??™ve seen an overview of many of the features in iptables and gotten a basic understanding
of what it can do. Creating complex firewalls, especially in situations where there are a lot of
people trying to break in, requires a much deeper knowledge of iptables. I suggest that, from here,
you refer to the following:
iptables Tutorial (http://iptables-tutorial.frozentux.net)??”This tutorial by
Oskar Andreasson is the standard by which other iptables information is measured.
netfilter project (www.netfilter.org)??”Get the latest information about iptables
development, patches, security issues, mailing lists, and news.
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