Ubuntu/virtualbox

Virtualbox is a virtual machine application & manager

list virtualbox vms|runningvms

vboxmanage list vms|runningvms

control virtualbox vm pause|resume|restart|poweroff

vboxmanage controlvm <uudi>|<name> [--details] [--statistics] [--machinereadab$

Internal network

In order to create a simple internal network between virtual machines, start by setting up the dhcp server from the host:

~$ vboxmanage dhcpserver add --netname intdhcp --ip 10.0.3.1 --netmask 255.255.255.0 --lowerip 10.0.3.2 --upperip 10.0.3.100 --enable

With this created, you can add a new network adapter to each virtual machine, making sure to use the same name as the netname you used for your dhcp server.
Thats it, your virtual machines should be able to talk with one another now.

host access/port forwarding

If you want to be able to access resources on the vm directly from your host, such as SSH, you can setup port forwarding on the virtual machine NAT adapter and bind it to a port on the host above 1024.
You only need to specify the protocol, host port, and guest port. The host ip and guest ip are not needed.