开启Ubuntu的NAT网络共享（封包转发方式局域网内共享上网）

We need open the ipv4 forwarding on the host 
sysctl -w net.ipv4.ip_forward = 1

Add follow lines into /etc/rc.locat to set NAT table

iptables -Fiptables -P INPUT ACCEPTiptables -P FORWARD ACCEPTiptables -t nat -A POSTROUTING -o [Sharing interface name] -j MASQUERADE      

Reboot the host device to enable the settings.

Set the host device IP （如果是多网卡方式组建局域网，需将网关设置为连接外网的网卡的IP， 内网网卡仅仅作AP点用）as gateway on the associate device

Google DNS server can be use Google free DNS 8.8.8.8 | 8.8.4.4 or OpenDNS 208.67.222.222 | 208.67.220.220