Uma opção é alterar o adaptador de rede da máquina virtual para o modo de ponte; você deve poder acessar o servidor virtual das outras máquinas na rede, fornecendo o endereço IP do seu convidado.
Editar:
Para aspectos práticos, veja a documentação do VirtualBox em redes virtuais . Suas opções são usar redes interligadas
With bridged networking, VirtualBox uses a device driver on your host
system that filters data from your physical network adapter. This
driver is therefore called a "net filter" driver. This allows
VirtualBox to intercept data from the physical network and inject data
into it, effectively creating a new network interface in software.
When a guest is using such a new software interface, it looks to the
host system as though the guest were physically connected to the
interface using a network cable: the host can send data to the guest
through that interface and receive data from it. This means that you
can set up routing or bridging between the guest and the rest of your
network.
ou encaminhamento de porta :
As the virtual machine is connected to a private network internal to
VirtualBox and invisible to the host, network services on the guest
are not accessible to the host machine or to other computers on the
same network. However, like a physical router, VirtualBox can make
selected services available to the world outside the guest through
port forwarding. This means that VirtualBox listens to certain ports
on the host and resends all packets which arrive there to the guest,
on the same or a different port.
Portanto, no caso de um encaminhamento de porta NAT, você deve usar o seguinte comando:
VBoxManage modifyvm "VM name" --natpf1 "guesthttp,tcp,,80,,80"