Using LINUX as NAT gateway

Share your internet connection in your LAN by using Linux and IPTABLES. First, create a script and put it in your /etc/rc.d/ then name it gateway.sh like below..

root@localhost#vi /etc/rc.d/gateway.sh

then enter the following:
#!/bin/sh
echo “1″ > /proc/sys/net/ipv4/ip_forward
iptables -t nat -A POSTROUTING -o eth1 -j MASQUERADE

where eth1 is your interface connected to internet and eth0 is the interface connected to LAN. Then the ip address of your eth0 should be the ip gateway of the hosts connected to your LAN.

After you made that little script, put that in your rc.local file so it will run everytime the pc starts-up. Do it like this:

root@localhost#vi /etc/rc.d/rc.local

#at the end of all the script, enter the ff. line
/etc/rc.d/gateway.sh

then save it

Opps, we have not yet made that gateway.sh executable, so to make it, do it like this:
root@localhost#chmod +x /etc/rc.d/gateway.sh

now you can run that script or when you restart, it will just start.