I have an Ubuntu 12.10 system on my PC and an Android 4.1 system on my Galaxy Nexus. Now I would like to share the Internet connection of my PC via USB with my Phone. I have been searching with Google a lot, but I only found answers how you can share the Internet connection of the Phone with the PC, but I want it the other way around.
This is not possible. But if you have a rooted Android, there is a trick, it's called Reverse USB tethering. Check out this article, author did that on Fedora, but I guess there should be no problems achieving the same on Ubuntu.