How can I share Internet access between two computers via USB?
I have a single wired network connection via Ethernet, and two laptops (one Windows XP, the other Ubuntu). Either the Windows or Linux boxes could serve as the master.
You'll need a USB link cable.
Using USB Ethernet adapter
The Ethernet network will allow you to transfer data between more than two PCs. One of the computers must have an Ethernet adapter, even if the others have a USB port as you can make use of the crossover cable. You can do this by plugging a USB-to-Ethernet converter device in the other computers that possess a USB port.
The cable that you should use to connect two PCs together is called a USB networking cable. A tiny electronic circuit is used in the middle of the connection to allow the two PC to send data to one another. You should bear in mind that if you are using serial or parallel cables, you will not be able to transfer data between more than two computers. Hence, I will suggest you to use a Direct Cable Connection to be able to get the same specifications as an Ethernet cable.