The following how to contains procedures to configure an Ubuntu 10.04 LTS machine to be used as a NAT (Network Address Translation) gateway for sharing internet connection.
Part A. Configuring IP v4 forwarding option
A.1. Edit the sysctl.conf file by issuing command: nano /etc/sysctl.conf and un-commented (remove hash mark) from the following line # net.ipv4.ip_forward=1
A.2. Open the rc.local file by issuing command: nano /etc/rc.local, next, add the following lines before exit 0 line
/sbin/iptables -P FORWARD ACCEPT
/sbin/iptables –table nat -A POSTROUTING -o eth0 -j MASQUERADE
(to be continued)