This question already has an answer here:
This question is not duplicate of this, because in my case, internet connection doesn't work on any version of Ubuntu as host (11.04, 12.04,.12.10), and the solution is different too, mine needed VirtualBox and extension pack from official website, not from USC, and it solved the problem.
Here is the question:
I downloaded VirtualBox from Ubuntu Software Center and had installed Lubuntu and Windows XP inside VirtualBox. Both are connected via NAT, I have tried other options too, but none of them works.
How do I share internet from host OS to guest OS? I'm using USB modem mobile broadband connection on host OS (Ubuntu Quantal).
I have read No internet connectivity in virtual-box with both Host and Virtual OS being 12.04, but still I don't know what to do. Can you give me step-by-step solution?