This document helps you to set up a small Linux based gateway as quick as possible.
run the following commands on the gateway machine:
switch into root user
1: user$ sudo -i
Enable packet forwarding by kernel
2: root$ echo 1 > /proc/sys/net/ipv4/ip_forward
exit root user
3: root$ exit
append the forwarding rule:
4: user$ iptables -A FORWARD -i eth0 [-s, --source [!] address[/mask]] -o ppp0 -j ACCEPT
e.g: user$ iptables -A FORWARD -i eth0 -s 192.168.1.45 -o ppp0 -j ACCEPT
altering the packets as they are about to go out
5: user$ sudo iptables -t nat -A POSTROUTING -o ppp0 -j MASQUERADE
and finally set gateway on the client machine, if you are running on Linux you can do it simply by executing this command:
user$ sudo route add default gw
to configure more complicated gateway you can refer to :
http://newbiedoc.sourceforge.net/networking/homegateway.html
http://www.yolinux.com/TUTORIALS/LinuxTutorialIptablesNetworkGateway.html
