VirtualBox in GNS3 under Linux part2

Continuing the previous post  VirtualBox in GNS3 under Linux part1, I will show below the steps on how to make GNS3 work with Virtualbox using emulated VirtualBox host-only adapters. 

STEP 1 : Install VirtualBox and VMs
Install VirtualBox (current version is 4.3.6) and your favorite Virtual Machines.