Each of the eight networking adapters can be separately configured to operate in one of the following modes:
- Not attached
-
In this mode, VirtualBox reports to the guest that a network card is present, but that there is no connection -- as if no Ethernet cable was plugged into the card. This way it is possible to "pull" the virtual Ethernet cable and disrupt the connection, which can be useful to inform a guest operating system that no network connection is available and enforce a reconfiguration.
- Network Address Translation (NAT)
-
If all you want is to browse the Web, download files and view e-mail inside the guest, then this default mode should be sufficient for you, and you can safely skip the rest of this section. Please note that there are certain limitations when using Windows file sharing (see Section 6.3.3, “NAT limitations” for details).
- NAT Network
-
The NAT network is a new NAT flavour introduced in VirtualBox 4.3. See 6.4 for details.
- Bridged networking
-
This is for more advanced networking needs such as network simulations and running servers in a guest. When enabled, VirtualBox connects to one of your installed network cards and exchanges network packets directly, circumventing your host operating system's network stack.
- Internal networking
-
This can be used to create a different kind of software-based network which is visible to selected virtual machines, but not to applications running on the host or to the outside world.
- Host-only networking
-
This can be used to create a network containing the host and a set of virtual machines, without the need for the host's physical network interface. Instead, a virtual network interface (similar to a loopback interface) is created on the host, providing connectivity among virtual machines and the host.
- Generic networking
-
Rarely used modes share the same generic network interface, by allowing the user to select a driver which can be included with VirtualBox or be distributed in an extension pack.
At the moment there are potentially two available sub-modes:
- UDP Tunnel
-
This can be used to interconnect virtual machines running on different hosts directly, easily and transparently, over existing network infrastructure.
- VDE (Virtual Distributed Ethernet) networking
-
This option can be used to connect to a Virtual Distributed Ethernet switch on a Linux or a FreeBSD host. At the moment this needs compiling VirtualBox from sources, as the Oracle packages do not include it.
The following table provides a quick overview of the most important networking modes:
Table 6.1. Overview
| VM ↔ Host | VM1 ↔ VM2 | VM → Internet | VM ← Internet | |
|---|---|---|---|---|
| Host-only | + | + | – | – |
| Internal | – | + | – | – |
| Bridged | + | + | + | + |
| NAT | – | – | + | Port forwarding |
| NAT Network | – | + | + | Port forwarding |
The following sections describe the available network modes in more detail.