Virtual Networking in Oracle VirtualBox
Learn how VirtualBox virtual PCI Ethernet adapters work, compare AMD, Intel, and virtio-net models, and choose compatible adapter hardware and network modes.
Oracle VirtualBox gives each virtual machine (VM) one or more virtual network interfaces. A virtual machine is the isolated computer created by VirtualBox, while the guest operating system is the operating system installed inside that VM.
VirtualBox presents each enabled interface to the guest as a virtual PCI Ethernet card. The guest therefore sees network hardware, not merely an abstract connection. It must have a suitable driver—guest software that recognizes and operates the adapter—in order to use the interface.
How VirtualBox virtual networking works
Each VM can have up to eight virtual network cards. Every adapter slot can be enabled or disabled independently, assigned an adapter model, and connected using its own network attachment mode.
The configuration has two separate parts:
- Network adapter model: the virtual hardware type presented to the guest, such as AMD PCNet, Intel PRO/1000, or virtio-net.
- Network attachment mode: where that virtual adapter connects, such as a NAT connection, a bridged network, a host-only network, or an internal network.
Choosing a compatible adapter model solves the guest hardware and driver problem. Choosing the attachment mode determines how the working adapter reaches the host, other guests, local networks, or external networks. For an overview of the available connection choices, see VirtualBox network modes.
VirtualBox virtual network adapter models
A network adapter model is the emulated or paravirtualized network hardware type selected for a VM. VirtualBox provides six model choices in three broad groups: AMD PCNet models, Intel PRO/1000 models, and the paravirtualized virtio-net adapter.
Most of these are emulated adapters. VirtualBox imitates a conventional physical Ethernet card, and the guest uses a normal driver for that card. The exception is virtio-net, which is paravirtualized: the guest uses a virtualization-aware driver rather than a driver for a conventional physical NIC.
| Adapter family/model | Hardware identifier | Adapter type | Default status | Guest compatibility guidance | Typical use case |
|---|---|---|---|---|---|
| AMD PCNet PCI II | Am79C970A | Emulated conventional Ethernet | No | Useful when the guest includes a driver for this older AMD model. | Compatibility with guests expecting the PCNet PCI II device. |
| AMD PCNet FAST III | Am79C973 | Emulated conventional Ethernet | Yes | Broadly supported by many guest operating systems, although some systems, including Microsoft Vista, may not include its driver by default. | Default choice for a commonly supported guest. |
| Intel PRO/1000 MT Desktop | 82540EM | Emulated conventional Ethernet | No | Suitable for Microsoft Vista and later guest operating systems when the AMD driver is unavailable. | Vista or newer guests needing a familiar Intel adapter. |
| Intel PRO/1000 T Server | 82543GC | Emulated conventional Ethernet | No | An option that works without additional driver installation in Microsoft Windows XP. | Windows XP guests where an in-box driver is preferred. |
| Intel PRO/1000 MT Server | 82545EM | Emulated conventional Ethernet | No | Useful when imported virtual hardware is expected to resemble an Intel server adapter. | Virtual machines imported in open virtualization formats. |
| Paravirtualized Network Adapter | virtio-net | Paravirtualized Ethernet | No | Requires a compatible virtio network driver in the guest; it does not emulate a common physical network card. | Guests prepared for efficient virtualization-aware networking. |
AMD PCNet adapters
AMD PCNet FAST III: the default model
AMD PCNet FAST III, identified as Am79C973, is the default VirtualBox emulated Ethernet adapter. It is broadly compatible with many guest operating systems, making it a sensible starting point for a typical VM.
Default does not mean universally supported. Some guest systems, including Microsoft Vista, may not provide the AMD PCNet FAST III driver in their standard installation. If the guest cannot detect the adapter or reports missing network hardware, select a supported Intel PRO/1000 model instead.
AMD PCNet PCI II
AMD PCNet PCI II, identified as Am79C970A, is another emulated AMD adapter. Select it when a particular guest or imported VM expects this model. For a new general-purpose VM, AMD PCNet FAST III is normally the more appropriate AMD choice because it is the VirtualBox default.
Intel PRO/1000 adapters
Intel PRO/1000 is a family of emulated Intel Ethernet adapters. The models differ in their hardware identifiers and compatibility profiles, so selecting “Intel PRO/1000” is not enough: choose the specific model that matches the guest scenario.
- Intel PRO/1000 MT Desktop (82540EM): a suitable choice for Microsoft Vista and later guest operating systems when the default AMD PCNet FAST III driver is missing.
- Intel PRO/1000 T Server (82543GC): an option for Microsoft Windows XP when a driver available without additional installation is preferred.
- Intel PRO/1000 MT Server (82545EM): useful when importing a virtual machine in an open virtualization format from another virtualization platform.
An open virtualization format is a portable virtual appliance format. An imported appliance may have been built around particular virtual hardware assumptions. Matching those expectations with Intel PRO/1000 MT Server can improve compatibility, although the guest driver should still be verified.
Paravirtualized networking with virtio-net
virtio-net is a paravirtualized network adapter. It does not pretend to be a common physical network card such as an AMD PCNet or Intel PRO/1000 device. Instead, the guest communicates through a virtualization-aware virtio driver.
This design can be efficient because the guest and virtualization software use an interface designed for virtual machines. The trade-off is compatibility: a guest without a suitable virtio network driver may show no usable network interface. Before selecting virtio-net, confirm that the guest includes or can install the required driver.
If a virtio-net guest has no network interface, either install a compatible virtio driver or change the adapter model to an emulated AMD PCNet or Intel PRO/1000 model supported by that guest.
How to select an adapter in VirtualBox
- Power off the VM if it is running, then open the selected VM's Settings.
- Open the Network section.
- Select an adapter slot and enable the Enable Network Adapter control.
- Use the Adapter Type control to choose AMD PCNet FAST III, an Intel PRO/1000 model, or virtio-net.
- Configure the adapter's network attachment mode separately.
- Start the guest and verify that its operating system detects the adapter and loads a driver.
- For additional connections, enable more adapter slots and configure each adapter independently. Do not exceed eight virtual network cards per VM.
The order matters when troubleshooting: first choose guest-compatible virtual hardware, then configure where that hardware connects. A correct network mode cannot make an unsupported adapter model work inside the guest.
Adapter-selection examples
| Guest or scenario | Recommended adapter | Reason | Driver consideration |
|---|---|---|---|
| Typical broadly supported guest | AMD PCNet FAST III (Am79C973) | It is the VirtualBox default and is broadly supported. | Confirm that the guest includes the AMD PCNet FAST III driver. |
| Microsoft Vista and later | Intel PRO/1000 MT Desktop (82540EM) | It is a suitable Intel alternative when the default AMD driver is unavailable. | Use the guest's Intel adapter driver or install one if required. |
| Microsoft Windows XP | Intel PRO/1000 T Server (82543GC) | It is an option that works without additional driver installation in Windows XP. | Prefer this model when an immediately available in-box driver is important. |
| Imported open virtualization format appliance | Intel PRO/1000 MT Server (82545EM) | It is useful for imported VMs whose expected virtual hardware resembles this Intel server adapter. | Check the imported guest's existing network configuration and driver. |
| Guest with virtio driver support | Paravirtualized Network Adapter (virtio-net) | It uses a virtualization-aware interface rather than emulating a physical NIC. | A compatible virtio network driver is required. |
Practical configurations
Default guest setup
Create or open a VM, enable its first network adapter, and leave the adapter model as AMD PCNet FAST III. After installing the guest operating system, inspect its network settings. If the guest detects an Ethernet adapter and loads a driver, configure the required attachment mode and test connectivity.
Microsoft Vista or newer without the AMD driver
If Vista or a later guest does not detect AMD PCNet FAST III, power off the VM and select Intel PRO/1000 MT Desktop. Boot the guest again and allow it to detect the Intel adapter. This changes the virtual hardware model; it does not by itself choose whether the interface uses NAT, bridged networking, or another connection type.
Windows XP with an in-box driver preference
For a Windows XP VM that needs a readily available driver, select Intel PRO/1000 T Server. If the guest still lacks connectivity, check both the guest's device status and the adapter's attachment mode rather than assuming that the model alone controls network access.
Imported appliance
After importing an appliance in an open virtualization format, review its adapter model and guest network configuration. If compatibility problems appear, evaluate Intel PRO/1000 MT Server as the selected model, then verify that the guest recognizes the resulting virtual hardware.
High-efficiency guest networking
For a guest prepared with a compatible virtio driver, select virtio-net. For a guest that does not have virtio support, use an emulated AMD PCNet or Intel PRO/1000 model instead. The most efficient model is not useful if the guest cannot load its driver.
Multiple network connections
A VM might use one adapter for external access and another for a private connection to the host or other VMs. Enable multiple adapter slots, select a compatible model for each, and assign an attachment mode to each adapter. VirtualBox supports up to eight virtual network cards per VM, and each adapter can have its own attachment configuration.
Troubleshooting adapter problems
The guest does not detect a network adapter
The selected model may not have a built-in guest driver. Confirm the adapter is enabled, then choose a supported Intel PRO/1000 model or install the appropriate guest driver. For Vista and later, consider Intel PRO/1000 MT Desktop.
Windows XP has no working connection
The selected model may not have an immediately available Windows XP driver. Try Intel PRO/1000 T Server when an out-of-box driver is required. Also check the attachment mode and the guest's own network configuration.
virtio-net provides no usable interface
This usually means the guest lacks a compatible virtio network driver. Install the required driver if the guest supports it, or switch to an emulated AMD PCNet or Intel PRO/1000 adapter.
An imported appliance has adapter compatibility issues
The appliance may expect virtual hardware different from the current selection. Review its original adapter expectations and evaluate Intel PRO/1000 MT Server for an imported open virtualization format appliance.
The VM needs separate connections but has only one
Only one adapter slot may be enabled. Enable additional slots, select a model for each, and configure each adapter's attachment mode independently, staying within the eight-adapter limit.
Exam-relevant summary
- A VirtualBox VM can have up to eight virtual PCI Ethernet cards.
- The guest sees a virtual adapter as hardware and needs a suitable driver.
- AMD PCNet FAST III (Am79C973) is the default adapter and is broadly compatible, but it may not be supported by default in Microsoft Vista.
- Intel PRO/1000 MT Desktop (82540EM) is suitable for Vista and later guests.
- Intel PRO/1000 T Server (82543GC) is an option for Windows XP without additional driver installation.
- Intel PRO/1000 MT Server (82545EM) is useful for imported open virtualization format appliances.
- virtio-net is paravirtualized and requires a compatible virtio guest driver.
- Adapter model and network attachment mode are separate settings.
For hands-on setup, continue with VirtualBox network modes, or study the specific guides for bridged networks, host-only networks, internal networking, and NAT networks.