Ubuntu/Debian Internet Gateway for Internet Connections Sharing

Two lines of commands to activating Internet Gateway on Ubuntu/Debian for desktop computer has 2 NIC (network interface card). This function will gone after you restart the computer.

#echo 1 > /proc/sys/net/ipv4/ip_forward
#iptables -t nat -A POSTROUTING -j MASQUERADE

Internet Sharing Connections (ICS) on Ubuntu

First you must have GSM/CDMA Broadband Internet  from any modems on active 

Very simple to make your computer as Internet Connections Sharing (ICS) on Ubuntu

This is sharing internet to wired (LAN), you just edit ipv4 Settings.

Now you can share internet to others via crossover cable (one computer) or (more computers) via hub