How to use the Internet connection of the computer from an Android device connected through USB. You need root access, and the Terminal Emulator installed.
Heavily inspired by http://www.alex.ballas.org/2012/02/13/android-reverse-tethering-on-linux/
on the Android device, activate “USB tethering” (should be under “Wireless and network settings” on recent versions)
on the computer, start Firestarter: in the configuration dialog, give the network card currently providing Internet connection (such as “eth0”, or “wlan0”) and, in the following page, the network card represented by the USB cable - should be called “usb0”
on the Android device, start the Terminal Emulator: run “su”, and then
ip route add default via 192.168.42.130
NOTE: between step 2) and 3), you can:
on the Android device, (install, if you didn't, and) start the wonderful WiFi Keyboard
, which makes sending any command much faster, since you can use your computer's keyboard.