NAT EXPLANATION

Network Address Translation (NAT) is the simplest way of accessing an external network from a virtual machine. Usually, it does not require any configuration on the host network and guest system. For this reason, it is the default networking mode in VirtualBox.

A virtual machine with NAT enabled acts much like a real computer that connects to the Internet through a router. The “router”, in this case, is the VirtualBox networking engine, which maps traffic from and to the virtual machine transparently. In VirtualBox this router is placed between each virtual machine and the host. This separation maximizes security since by default virtual machines cannot talk to each other.

The disadvantage of NAT mode is that, much like a private network behind a router, the virtual machine is invisible and unreachable from the outside internet; you cannot run a server this way unless you set up port forwarding (described below).

BRIDGE EXPLANATION

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.

Source: networking – Can’t get dhcp ip in my virtual machine on Virtual box – Super User

Source: How to Manually Set Your IP in Linux (including netplan) | Daniel Miessler

VBoxManage setproperty vrdeextpack “Oracle VM VirtualBox Extension Pack”

Source: virtualbox.org • View topic – rdesktop connection rejected – VRDE and VNC on same port

Changing Network Configuration

Below is an example of a static IP configuration on a system with only one Ethernet interface (eth0) and 10.0.0.41/24 for the IP address. Opening the /etc/network/interfaces file will produce:

# This file describes the network interfaces available on your system
# and how to activate them. For more information, see interfaces(5).

# The loopback network interface
auto lo
iface lo inet loopback

# The primary network interface
auto eth0
iface eth0 inet static
    address 10.0.0.41
    netmask 255.255.255.0
    network 10.0.0.0
    broadcast 10.0.0.255
    gateway 10.0.0.1
    dns-nameservers 10.0.0.1 8.8.8.8
    dns-domain acme.com
    dns-search acme.com

Source: Configure Node Networking — SwiftStack Documentation

Starting and Connecting to the Virtual Machine

After the successful installation of VRDP, a virtual machine can be started in headless mode. The name of the virtual machine will be given in the first step:

~$ VBoxManage list vms
"ubuntu-server" {763d57b9-8eef-4572-8e71-f33fea89e950}

In this example, there is a virtual machine named “ubuntu-server”. The subsequent number is its UID. Headless mode can be activated afterwards in one of two manners:

~$ VBoxHeadless -s ubuntu-server
Oracle VM VirtualBox Headless Interface 4.1.8
(C) 2008-2011 Oracle Corporation
All rights reserved.

VRDE server is listening on port 3389.

or:

~$ VBoxManage startvm ubuntu-server --type headless
Waiting for VM "ubuntu-server" to power on...
VM "ubuntu-server" has been successfully started.

The virtual machine will now be running, however display output will not be shown. Instead, one connects to the machine through RDP or SSH (assuming that corresponding network and SSH configurations) exist.

SSH

~$ ssh tktest@192.168.56.101

In this example, the virtual machine has one Host-only-Adapter, which will automatically get an IP address from the DHCP server when the virtual machine is started. For that reason, the running SSH server for the virtual machine can be reached without any problems. This connection will also work through SSH, if VRDE has not been activated for the virtual machine.

RDP

Connection to a virtual machine via RDP will only work when VRDE has been activated for the virtual machine. After that, any RDP client can be used for connecting to the local host or using the IP address for the host on the virtual machine:

~$ VBoxHeadless -s ubuntu-server
Oracle VM VirtualBox Headless Interface 4.1.8
(C) 2008-2011 Oracle Corporation
All rights reserved.

VRDE server is listening on port 3389.

rdesktop localhost

Source: Headless Mode for Virtual Machines of VirtualBox – Thomas-Krenn-Wiki