Nat – In NAT mode VirtualBox DHCP only has one IP to assign

There are several ways you can approach this:

• Don't use a NAT adapter. I realize this may not be possible/desirable, but if you can select "Bridged" adapter and get an IP from that same subnet, all these problems (both gust->host and host->guest) go away.

• Use two virtual adapters, the regular NAT one for internet access, and a second "loopback" adapter in bridged mode on your own private subnet. The loopback will be used for communication between the host and guest(s), while the NAT adapter will handle the traffic outside of the host.

• There are a number of tricks to do port forwarding to the hosts, as well as open up guests to see the host. By default, I believe, both of these are blocked as to provide a better sandbox. There are plenty of questions here on Server Fault (tagged with VirtualBox) that talk about punching holes as described.

In NAT networking mode, VirtualBox machines can talk to the Internet, but not to each other.

In host-only networking mode, the virtual machines can talk to each other, but not to the Internet. (Though you could NAT them manually if you are on a Linux or FreeBSD host.)

Another option is VDE networking; this is only available in the community edition, and not the Oracle edition of VirtualBox, and only on Linux and FreeBSD hosts. It's much more involved to set up, but would do what you want once done.

The fastest and easiest way to set this up is, of course, bridged mode.