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<topic xml:lang="en-us" id="network_bridged">
  <title>Bridged Networking</title>
  
  <body>
    <p>With bridged networking, <ph conkeyref="vbox-conkeyref-phrases/product-name"/> uses a device driver on your <i>host</i> system that filters data from your physical network adapter. This driver is therefore called a <i>net filter</i> driver. This enables <ph conkeyref="vbox-conkeyref-phrases/product-name"/> to intercept data from the physical network and inject data into it, effectively creating a new network interface in software. When a guest is using such a new software interface, it looks to the host system as though the guest were physically connected to the interface using a network cable. The host can send data to the guest through that interface and receive data from it. This means that you can set up routing or bridging between the guest and the rest of your network.</p>
    <note>
      <p>Even though TAP interfaces are no longer necessary on Linux for bridged networking, you <i>can</i> still use TAP interfaces for certain advanced setups, since you can connect a VM to any host interface.</p>
    </note>
    <p>To enable bridged networking, open the <b outputclass="bold">Settings</b> for a virtual machine, go to the <b outputclass="bold">Network</b> page and select <b outputclass="bold">Bridged Network</b> for the <b outputclass="bold">Attached To</b> field. Select a host interface from the list at the bottom of the page, which contains the physical network interfaces of your systems. On a typical MacBook, for example, this will allow you to select between en1: AirPort, which is the wireless interface, and en0: Ethernet, which represents the interface with a network cable.</p>
    <note>
      <p>Bridging to a wireless interface is done differently from bridging to a wired interface, because most wireless adapters do not support promiscuous mode. All traffic has to use the MAC address of the host's wireless adapter, and therefore <ph conkeyref="vbox-conkeyref-phrases/product-name"/> needs to replace the source MAC address in the Ethernet header of an outgoing packet to make sure the reply will be sent to the host interface. When <ph conkeyref="vbox-conkeyref-phrases/product-name"/> sees an incoming packet with a destination IP address that belongs to one of the virtual machine adapters it replaces the destination MAC address in the Ethernet header with the VM adapter's MAC address and passes it on. <ph conkeyref="vbox-conkeyref-phrases/product-name"/> examines ARP and DHCP packets in order to learn the IP addresses of virtual machines.</p>
    </note>
    <p>Depending on your host operating system, the following limitations apply:</p>
    <p><b outputclass="bold">macOS hosts</b></p>
    <ul>
      <li>
        <p> Functionality is limited when using AirPort, the Mac's wireless networking system, for bridged networking. Currently, <ph conkeyref="vbox-conkeyref-phrases/product-name"/> supports only IPv4 and IPv6 over AirPort. For other protocols, such as IPX, you must choose a wired interface.</p>
      </li>
    </ul>
    <p><b outputclass="bold">Linux hosts</b></p>
    <ul>
      <li>Functionality is limited when using wireless interfaces for bridged networking. Currently, <ph conkeyref="vbox-conkeyref-phrases/product-name"/> supports only IPv4 and IPv6 over wireless. For other protocols, such as IPX, you must choose a wired interface.</li>
      <li>Also, setting the MTU to less than 1500 bytes on wired interfaces provided by the sky2 driver on the Marvell Yukon II EC Ultra Ethernet NIC is known to cause packet losses under certain conditions.</li>
      <li>
        <p>Some adapters strip VLAN tags in hardware. This does not allow you to use VLAN trunking between VM and the external network with Linux kernels before 2.6.27, or with host operating systems other than Linux.</p>
      </li>
    </ul>
    <p><b outputclass="bold">Oracle Solaris hosts</b></p>
    <ul>
      <li>There is no support for using wireless interfaces. Filtering guest traffic using IPFilter is also not completely supported due to technical restrictions of the Oracle Solaris networking subsystem. These issues may be addressed in later releases of Oracle Solaris 11.</li>
      <li>On Oracle Solaris 11 hosts build 159 and above, it is possible to use Oracle Solaris Crossbow Virtual Network Interfaces (VNICs) directly with <ph conkeyref="vbox-conkeyref-phrases/product-name"/> without any additional configuration other than each VNIC must be exclusive for every guest network interface.</li>
      <li>When using VLAN interfaces with <ph conkeyref="vbox-conkeyref-phrases/product-name"/>, they must be named according to the PPA-hack naming scheme, such as e1000g513001. Otherwise, the guest may receive packets in an unexpected format.</li>
      <li>VirtualBox guests can't use bridged networking over an aggregate link (also known as a single link aggregation) on Oracle Solaris 11 FCS hosts. However, you can use <userinput>dladm</userinput> to manually create a VNIC over the aggregate link and use that with a VM. This limitation does not exist in Oracle Solaris 11 update 1 (11.1) and later.</li>
    </ul>
  </body>
  
</topic>
