Up to eight virtual PCI Ethernet cards are supported in VirtualBox in each guest VM. Out of the eight virtual Ethernet cards, four of them can be configured in the Network section of the Settings dialog in the VirtualBox GUI.

VirtualBox can virtualize six types of networking hardware, listed as follows:

AMD PCNet FAST III is the default hardware because it is supported by most of the current operating systems out of the box, and is also supported by the GNU GRUB boot manager. Operating systems such as Microsoft Vista don't ship by default with this driver; that's the reason why Intel PRO/1000 family adapters are chosen for this type of guest OS. The Intel PRO/1000 MT desktop driver works with operating systems such as Microsoft Vista and later versions.

For operating systems such as Microsoft XP, the T Server variant of the Intel PRO/1000 card works out of the box without additional driver installation. The MT Server variant helps to import open virtualization formats from other platforms.

Starting with Version 3.1, VirtualBox provides support for the industry-standard virtio networking drivers, which are a part of the open-source Kernel-based Virtual Machine (KVM) project. If you select this driver, VirtualBox does not virtualize common networking hardware; rather, it expects a special software interface for virtualized environments to be provided by the guest, which avoids the complexity of emulating networking hardware and improving network performance.

The virtio networking drivers are available for Linux kernel versions 2.6.25 or later.