Starting a fw

[Visham Ramsurrun <vishamr2000@gmail.com>]

Hi to all,

I was once told that in order to start a firewall automatically when a
machine boots, we must make sure that the init process calls the
script by making a symbolic link to that file in the /etc/rc.d/rcX.d
directories.

I have found that there is a file called S08iptables (kernel 2.4.20-8)
containing startup commands for iptables service. Do i delete it and
then put the symbolic link to my script there or just leave it?

Let's say I have a firewall script called fw.sh with the following rules in it:

#!/bin/bash
IPT=/sbin/iptables

$IPT -F
$IPT -X
$IPT -P INPUT DROP
$IPT -P OUTPUT DROP
$IPT -P FORWARD DROP

$IPT -A FORWARD -i eth0 -o eth0 -s 192.168.10.0/24 -d 192.168.10.0/24
-m state --state NEW,ESTABLISHED,RELATED -p icmp --icmp-type echo
request -j ACCEPT

$IPT -A FORWARD -i eth0 -o eth0 -s 192.168.10.0/24 -d 192.168.10.0/24
-m state --state NEW,ESTABLISHED,RELATED -p icmp --icmp-type echo
reply -j ACCEPT

What steps (where to create symbolic links, at which runlevel, etc)
should I take in order to have this script be started automatically
when PC boots up. How can I make sure that it is this firewall script
that is running and all packets are being checked against these rules?

Thx in advance..

Warm regards,
Visham