6 Virtual networking As briefly mentioned in chapter 3.8, Network settings, page 48, VirtualBox provides up to eight virtual PCI Ethernet cards for each virtual machine. For each such card, you can individually select 1. the hardware that will be virtualized as well as 2. the virtualization mode that the virtual card will be operating in with respect to your physical networking hardware on the host. Four of the network cards can be configured in the “Network” section of the settings dialog in the graphical user interface of VirtualBox. You can configure all eight network cards on the command line via VBoxManage modifyvm see chapter 8.7, VBoxManage modifyvm, page 109. This chapter explains the various networking settings in more detail. 6.1 Virtual networking hardware For each card, you can individually select what kind of hardware will be presented to the virtual machine. VirtualBox can virtualize the following six types of networking hardware: • AMD PCNet PCI II (Am79C970A) • AMD PCNet FAST III (Am79C973, the default) • Intel PRO/1000 MT Desktop (82540OEM) • Intel PRO/1000 T Server (82543GC) • Intel PRO/1000 MT Server (82545EM) • Paravirtualized network adapter (virtio-net). The PCNet FAST III is the default because it is supported by nearly all operating systems out of the box, as well as the GNU GRUB boot manager. As an exception, the Intel PRO/1000 family adapters are chosen for some guest operating system types that no longer ship with drivers for the PCNet card, such as Windows Vista see chapter 4.2.1.5, Windows Vista networking, page 56 for details.1 The “Paravirtualized network adapter (virtio-net)“ is special. If you select this, then VirtualBox does not virtualize common networking hardware (that is supported by common guest operating systems out of the box). Instead, VirtualBox then expects a special software interface for virtualized environments to be provided by the guest, thus avoiding the complexity of emulating networking hardware and improving network performance. Starting with version 3.1, VirtualBox provides support for the industry-standard “virtio” networking drivers, which are part of the open-source KVM project. The “virtio” networking drivers are available for the following guest operating systems: 1Support for the Intel PRO/1000 MT Desktop type was added with VirtualBox 1.6. The T Server variant of the Intel PRO/1000 card was added with VirtualBox 1.6.2 because this one is recognized by Windows XP guests without additional driver installation. The MT Server variant was added with VirtualBox 2.2 to facilitate OVF imports from other platforms. 83