Or have you generated a firewall scrit and placed it in /etc/sysconfig/iptables?
I think the best way to go is to write your own script for the router.
Open an editor and put:
echo " External Interface: $EXTIF"
echo " Internal Interface: $INTIF"
echo "1" > /proc/sys/net/ipv4/ip_forward
echo "1" > /proc/sys/net/ipv4/ip_dynaddr
iptables -P INPUT DROP
iptables -F INPUT
iptables -P OUTPUT DROP
iptables -F OUTPUT
iptables -P FORWARD DROP
iptables -F FORWARD
iptables -t nat -F
iptables -t nat -A POSTROUTING -o $EXTIF -j MASQUERADE
iptables -A FORWARD -i $EXTIF -o $INTIF -m state --state ESTABLISHED,RELATED -j ACCEPT
iptables -A FORWARD -i $INTIF -o $EXTIF -j ACCEPT
iptables -A INPUT -p ALL -i $INTIF -s 192.168.0.0/8 -j ACCEPT
iptables -A OUTPUT -p ALL -s 127.0.0.1 -j ACCEPT
iptables -A OUTPUT -p ALL -o eth1 -j ACCEPT
iptables -A OUTPUT -p ALL -o eth0 -j ACCEPT
That should get you going. If you save the file as "firescript", make it executable by: chmod 700 firescript
then: sh firescript
then see if it was loaded: iptables -L
then: iptables-save > /etc/sysconfig/iptables
(All that was done on your router)
Then make sure you're using crossover cables.
Set up new internet connections (using wizard) in each networked box.
(You'll need to get DNS addresses for the internal boxes from the router)
I think that's pretty close...
If you get errors, go here
and look for modules to load by adding them to the above script. Good luck!!