After Firewalld open, L2TP can not access the Internet

When closed Firewalld, configure the L2TP, after connecting on just ppp0 packets forwarded to the device through the iptables nat table:

iptables -t nat -A POSTROUTING -s 172.16.1.0/24 -o eth0 -j MASQUERADE

 

However, if the open Firewalld, even though I joined ppp0 opened the external area masquerade still unable to access the Internet.

May I ask how to configure forwarding rules (best to use firewall-cmd tool)?

firewall-cmd --permanent --direct --add-rule ipv4 filter INPUT 0 -p gre -j ACCEPT
firewall-cmd --permanent --direct --add-rule ipv4 filter POSTROUTING 0 -t nat -o eth0 -j MASQUERADE
firewall-cmd --reload

Note the name of the card!