Done! I added a new wired connection, giving the kobo MAC address and setting a manual ip with address 192.168.2.100 and netmask the usual 255.255.255.0.
You can find the MAC address using ifconfig usb0 (it's the HWaddr).
Thank you all very very much!
EDIT: I have only a big trouble, I must change every time the MAC address, since it's not the MAC address of the physical device, but the usb0 MAC. If you know a way to make it static, give me a call
RE-EDIT: I probably found a way:
http://en.qi-hardware.com/wiki/Ether...ic_Mac_Address