I followed the instructions of M. Rostami here: https://raspberrypi.stackexchange.com/a/106878/139008
My setup is Android (tether on) -> USB -> Raspberri Pi 4 (Buster) -> Ethernet -> Windows10
- Android phone has internet access.
- Raspberry Pi has internet access.
- Win10 does't have internet access.
- Win10 can ping 192.168.100.254 and can ping the Android Phone.
NOTE: I had to modify some of the instructions as my tether android phone appears as usb0:
sudo iptables -t nat -A POSTROUTING -o eth0 -j MASQUERADE sudo iptables -A FORWARD -i eth0 -o usb0 -m state --state RELATED,ESTABLISHED -j ACCEPT sudo iptables -A FORWARD -i usb0 -o eth0 -j ACCEPT
After reboot, using
sudo iptables -S I was able to check that the firewall config does get reapplied on each startup.
I don't really know where to even start looking. Any pointer is appreciated.