VirtualBox 4.3.12 configuration

File->"Preferences"->Click "Network" in left panel -> Add a new NAT network

Name -> "MyNAT"
CIDR: 192.168.0.0/24
Click the "Port forwarding" add port "22" in Ipv4.
Name "SSH"
Protocol "TCP"
Host IP "10.2.2.72" (run "cmd"->"ipconfig" to get it)
Host Port "22"
Guest IP "192.168.0.4" (The IP of the primary virtual machine)
Guest Port "22"


For each virtual machine, in "Settings"->"network"->"Adapter1"->"NAT Network" choose "MyNAT"