My WIFI is connected to the Internet. I want share Internet with a device that doesn't have wifi via the WIRED ethernet ports.
Using systemd-networkd I configure
/etc/systemd/network/wifi.network like so:
[Match] Name=wl* [Network] DHCP=ipv4 LinkLocalAddressing=no IPForward=ipv4
Notice IPForward which is key.
My WIRED ethernet port is configured by
/etc/systemd/network/wired.network like so:
[Match] Name=enp0s25 [Network] Address=0.0.0.0/28 LinkLocalAddressing=no DHCPServer=yes IPMasquerade=yes
Notice my DHCPServer so that the client to the network port can get an IP.
I use this networking technique when wire sharking.