I have been struggeling with this problem for a while now. I have a rpi2 that accesses the web via 4g. I would like to connect the zero to the rpi2 with the usb and share the internet connection that the rpi2 has. I have managed to do it once, but after a reboot it dissapared. I have found a tutorial about using the GPIO pins, but i would like to use the USB, cuz most of my gpio pins are taken by a navio board.