Oracle Virtualbox

Configure Bridged Networking in Oracle VirtualBox

Learn how to configure a VirtualBox VM with a Bridged Adapter so it can join the host's physical LAN, obtain network settings, and communicate with other approved devices.

Bridged networking connects a guest virtual machine (VM) to the same physical network used by the host computer. Unlike NAT, the guest does not normally share the host's network address for outbound communication. Instead, it appears as a separate network participant on the selected LAN.

This configuration is useful when a development or server VM must access office resources, internal DNS, package repositories, NTP time sources, or other services available on the physical network. When network policy permits it, other devices on that LAN can also connect to services running in the guest.

What Bridged Networking Means

Bridged networking is a VirtualBox network attachment mode that connects a guest VM through a host physical network adapter. A physical network adapter is an Ethernet, Wi-Fi, or similar interface connected to a real network.

The guest receives its own network identity according to the requirements of that LAN. For example, a DHCP server on the LAN may assign the guest an IP address, subnet information, gateway, and DNS servers. Alternatively, the guest can use valid static settings supplied by the network administrator.

Because the guest is a separate participant, it can communicate with systems and services available on the physical network. This can include DNS resolvers, NTP servers, file services, web services, and approved client devices. Reachability is still controlled by guest firewalls, LAN policy, wireless client isolation, service configuration, and routing.

How VirtualBox Bridging Works

VirtualBox uses a host-side network filter driver, commonly called the net filter, with the selected physical network adapter. The filter processes traffic entering and leaving the physical network on behalf of virtual machines.

On the host side, the virtualization networking layer provides a software network interface as a logical connection point between host networking and the guest. The bridge relationship allows traffic to pass between the guest's virtual network adapter and the physical network through the selected host adapter.

The path can be summarized as:

Guest VM virtual adapter <-> VirtualBox software network interface and net filter <-> Host physical adapter <-> Physical LAN

The host can have several possible adapters, such as wired Ethernet, Wi-Fi, VPN interfaces, and virtual-only interfaces. The adapter selected in VirtualBox determines which physical network the guest attempts to join.

Bridged Networking Compared with Other Modes

Mode — Guest relationship to the physical LAN — Typical use case — Inbound reachability from the LAN

Bridged Adapter — Guest participates as a separate device through a selected host physical adapter — Use when the guest must join the same LAN as the host — Often possible, subject to addressing, firewalls, and LAN policy

NAT — Guest uses VirtualBox translation through the host and is not normally a directly addressed LAN participant — General outbound Internet or network access with minimal guest exposure — Not normally directly reachable from the LAN without additional port forwarding

Internal Network — Guest communicates with other VMs attached to the same named internal network, without direct access to the host's physical LAN — Isolated multi-VM testing — Not reachable from the physical LAN

For a broader overview, see VirtualBox network modes and VirtualBox virtual networking.

Configure Bridged Networking for an Existing VM

  1. Open Oracle VM VirtualBox Manager.
  2. Select the existing virtual machine that you want to configure.
  3. Open the VM's Settings.
  4. Select the Network category.
  5. Open the adapter settings for the network adapter you want the guest to use.
  6. Ensure Enable Network Adapter is selected.
  7. Set Attached to to Bridged Adapter.
  8. In the adapter-name field, select the host physical network adapter connected to the intended network.
  9. Select OK to save the configuration.
  10. Start the VM, or restart its guest network connection if it was already running. The guest may need to request a new DHCP lease or apply its configured static settings.

The exact adapter labels depend on the host operating system and installed hardware. Choose the active Ethernet or Wi-Fi interface, not merely the first item in the list.

Choose the Correct Host Adapter

Suppose a laptop has both Ethernet and Wi-Fi. If Wi-Fi is currently connected to the desired office LAN, select the Wi-Fi adapter. If the laptop is connected through a network cable instead, select the active Ethernet adapter. Selecting an inactive interface can leave the guest without the expected connection.

  • Select the physical adapter that is currently connected to the intended network.
  • Avoid disconnected adapters unless you are deliberately preparing for a later connection.
  • Avoid VPN adapters, host-only adapters, virtual switch interfaces, and other virtual-only interfaces unless one is specifically the intended network path.
  • Remember that the selected adapter determines which physical network the guest joins.
  • On managed or wireless networks, confirm that the network permits additional devices and peer-to-peer communication.

Guest Network Addressing

Bridging changes the connection path, but the guest operating system still needs valid network configuration. Use DHCP when the selected LAN supplies addresses automatically. The guest should receive an address, subnet or prefix, default gateway, and DNS configuration appropriate for that LAN.

Use manual settings only when the network requires them or an administrator has supplied valid values. A static address must belong to the correct network, must not conflict with another device, and must use an appropriate gateway and DNS configuration.

A bridged guest may be reachable from another LAN device, but this is not guaranteed. The guest firewall must allow the intended service, the service must listen on the expected interface and port, and the physical network must allow device-to-device traffic.

Verification Checklist

Setting — Required value or action — Reason

Network Adapter enabled — Enable the adapter in the VM's Network settings — Gives the guest a virtual network device

Attached to — Set it to Bridged Adapter — Connects the guest through a host physical adapter

Host adapter selection — Choose the active Ethernet or Wi-Fi adapter for the intended LAN — Determines which physical network the guest joins

Save settings — Select OK — Applies the VirtualBox configuration

Guest network address verification — Confirm an appropriate address, gateway, and DNS configuration — Shows whether the guest successfully configured itself for the LAN

  1. Confirm that the guest adapter is enabled and reports a link or connection.
  2. Check the guest's network settings and verify that its address belongs to the intended LAN.
  3. Confirm that the guest has an appropriate gateway and DNS configuration.
  4. Test DNS resolution and access to an approved network host or service.
  5. Test time synchronization if the guest uses NTP.
  6. If required, connect from another LAN device to an approved service running in the guest.

Use the guest operating system's own network tools to inspect its address, routes, DNS settings, and connectivity. The commands vary by guest operating system, so interpret their output according to that system's networking tools.

Troubleshooting Bridged Networking

The guest has no network connection

  • Confirm that Enable Network Adapter is selected.
  • Check that Attached to is set to Bridged Adapter.
  • Choose the host adapter that is currently connected to the intended network.
  • Make sure the selected adapter is not disconnected, disabled, or unrelated to the desired network.
  • Restart the guest network connection or restart the guest VM.
  • Check whether the guest received an address, gateway, and DNS configuration appropriate for the LAN.

The guest has local connectivity but cannot resolve names or reach external services

  • Verify the guest's DNS settings.
  • Confirm that the guest can reach its configured gateway or another permitted network resource.
  • Check whether the physical network restricts access to the requested service.
  • Confirm that the service is available and that network policy allows the guest to use it.

Another LAN device cannot reach the guest

  • Verify that the guest address belongs to the intended physical network.
  • Confirm that the target service is running and listening on the expected interface.
  • Check the guest firewall and allow only the required service and source networks.
  • Check whether the LAN or Wi-Fi network uses client isolation or another peer-to-peer restriction.
  • Confirm that the correct host physical adapter is selected for bridging.

Practical Scenarios

Development VM on an office LAN

Select the host's active Ethernet adapter, use DHCP if the office network provides it, and verify access to internal DNS, package repositories, and approved time services.

Service VM accessed by another device

Bridge the server VM to the same LAN as the approved client. Verify the guest address, service listener, guest firewall, and LAN policy before testing the connection from the client.

Laptop switching between wired and wireless networks

When the laptop changes from Ethernet to Wi-Fi, review the bridged adapter selection. The guest must be bridged through the adapter that is connected to the desired network at that time.

Exam-Relevant Notes

  • Host: The physical computer running Oracle VM VirtualBox.
  • Guest VM: A virtual machine running inside VirtualBox.
  • Bridged Adapter: The VirtualBox attachment option used to enable bridged networking.
  • Net filter: The host-side VirtualBox network filter driver used with a physical adapter to handle traffic between the physical network and virtual machines.
  • DNS: Domain Name System, which resolves host names to network addresses.
  • NTP: Network Time Protocol, which synchronizes system time.
  • Bridged networking gives the guest a separate presence on the selected LAN; it is not the same as sharing the host's address through NAT.
  • Bridging does not bypass firewalls or network policy. Successful configuration and reachability are separate questions.

For related configurations, see Configure NAT networking and Configure internal networking.