My host OS is Fedora 18 (kernel: 3.11.10) and I am running VirtualBox 4.2.18. The only networking mode which is working is NAT and non of Bridged Adapter, Internal, and Host-Only do not work! By do not work, I mean when I start a virtual machine, I can't get an IP and ping my virtual machine. I really have no idea why this behaves like this since it was working previously without any problem. Any idea please?