Debin:
sudo iptables -t nat -A POSTROUTING -s 192.168.0.0/24 -o eth0 -j MASQUERADE
sudo iptables -I FORWARD -p tcp --syn -i ppp+ -j TCPMSS --set-mss 1396
Centos7.6:
https://www.xianba.net/4992.html 防火墙设置
https://www.cnblogs.com/bushaoxun/articles/7977579.html pptp安装
