I have enabled two adapters in my VirtualBox (running [Ubuntu 12.10 Server Edition](http://virtualboxes.org/images/ubuntu-server/)), with types as: Host-only and NAT.  

My main motive is to be able to connect two VMs running on two different hosts (physical machines) on a port (say 22). I know the answer is Port Forwarding, but it is too confusing. Well I have tried with Bridged mode, there too from outside my machine it is not able to connect to the virtual machine.

**Edit**: Well I wouldn't suggest Bridged Network, as it takes up IP addresses from the network, hence would prefer a NAT-ing technique.