iptables

iptables -F 
iptables -P INPUT ACCEPT 
iptables -P FORWARD ACCEPT 
sudo iptables -t nat -A POSTROUTING -j MASQUERADE
iptables -t nat -A POSTROUTING -o usb0 -j MASQUERADE 

sudo apt-get install iptables-persistent

该组件默认会将防火墙规则保存到
sudo vim /etc/iptables/rules.v4

#保存现有规则
sudo service netfilter-persistent save


#读取并应用先有规则
sudo service netfilter-persistent reload