Hello, Is it possible with Linux enable packet forwarding from one interface to another? Concretely, we would like to connect modem via usb port and then create PPP connection to internet. With this PPP connection we would like to forward packets from eth interface to PPP and vice versa. Is it possible with Linux? Is there iptables? Is it possible to install PPP or is there already?
Yes, it is possible to use packet forwarding from one interface to another. It would be something along the lines of
sudo sysctl -w net.ipv4.ip_forward=1
sudo iptables -t nat -A POSTROUTING -o eth0 -j MASQUERADE
You can look for examples on the net or the man pages. I have not verified the above.
The absence or presence of PPP depends on your kernel's configuration. You probably need the below at a minimum in your kernel configuration.