• http://os.51cto.com/art/201103/249341.htm
• http://www.xuebuyuan.com/1945506.html
• http://blog.csdn.net/wbryfl/article/details/6146617
• http://www.ahlinux.com/safe/16121.html
• http://linux.alai.net/viewblog.php?id=41605

• Edit /etc/network/interfaces

 This file describes the network interfaces available on your system
# and how to activate them. For more information, see interfaces(5).

source /etc/network/interfaces.d/*

# The loopback network interface
auto lo
iface lo inet loopback

# The primary network interface
allow-hotplug eth0
iface eth0 inet dhcp

# The secondary network interface
iface eth1 inet static
address 192.168.0.1
netmask 255.255.255.0

• Restart networking

# This does not work: /etc/init.d/networking restart
sudo ifdown eth1 && sudo ifup eth1

• Enable ip forward: edit /etc/sysctl.conf, uncomment “#net.ipv4.ip_forward=1”.

### OLD
#net.ipv4.ip_forward=1

### NEW
net.ipv4.ip_forward=1

• Now we should be alble to ping 192.168.0.1. To ping 166.111.142.1, we should do

 iptables -t nat -A POSTROUTING -s 192.168.0.0/24 -o eth0 -j MASQUERADE

• Set up DHCP server ( Ref)