Ip masquerade howto

Is there a howto setup Fedora server as a gateway with ipMasquerade?

Assuming the default setup with NetworkManager and firewalld:

nmcli connection show
nmcli connection modify LAN_CONNECTION connection.zone internal
nmcli connection modify WAN_CONNECTION connection.zone external
systemctl restart NetworkManager.service

Another method more suitable for systemd-networkd and firewalld:

firewall-cmd --get-active-zones
firewall-cmd --permanent --zone=internal --add-interface=LAN_INTERFACE
firewall-cmd --permanent --zone=external --add-interface=WAN_INTERFACE
firewall-cmd --reload