| 1 | <?xml version='1.0' encoding='UTF-8'?>
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| 2 | <!DOCTYPE topic PUBLIC "-//OASIS//DTD DITA Topic//EN" "topic.dtd">
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| 3 | <topic xml:lang="en-us" id="network_hostonly">
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| 4 | <title>Host-Only Networking</title>
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| 5 |
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| 6 | <body>
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| 7 | <p>Host-only networking can be thought of as a hybrid between the bridged and internal networking modes. As with
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| 8 | bridged networking, the virtual machines can talk to each other and the host as if they were connected through a
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| 9 | physical Ethernet switch. As with internal networking, a physical networking interface need not be present, and
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| 10 | the virtual machines cannot talk to the world outside the host since they are not connected to a physical
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| 11 | networking interface. </p>
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| 12 | <p>When host-only networking is used, <ph conkeyref="vbox-conkeyref-phrases/product-name"/> creates a new software
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| 13 | interface on the host which then appears next to your existing network interfaces. In other words, whereas with
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| 14 | bridged networking an existing physical interface is used to attach virtual machines to, with host-only networking
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| 15 | a new <i>loopback</i> interface is created on the host. And whereas with internal networking, the traffic between
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| 16 | the virtual machines cannot be seen, the traffic on the loopback interface on the host can be intercepted. </p>
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| 17 | <note>
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| 18 | <p>Hosts running recent macOS versions do not support host-only adapters. These adapters are replaced by host-only
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| 19 | networks, which define a network mask and an IP address range, where the host network interface receives the
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| 20 | lowest address in the range. </p>
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| 21 | <p>The host network interface gets added and removed dynamically by the operating system, whenever a host-only
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| 22 | network is used by virtual machines. </p>
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| 23 | <p>On macOS hosts, choose the <b outputclass="bold">Host-Only Network</b> option when configuring a network
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| 24 | adapter. The <b outputclass="bold">Host-Only Adapter</b> option is provided for legacy support. </p>
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| 25 | </note>
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| 26 | <p>Host-only networking is particularly useful for preconfigured virtual appliances, where multiple virtual machines
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| 27 | are shipped together and designed to cooperate. For example, one virtual machine may contain a web server and a
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| 28 | second one a database, and since they are intended to talk to each other, the appliance can instruct <ph
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| 29 | conkeyref="vbox-conkeyref-phrases/product-name"/> to set up a host-only network for the two. A second, bridged,
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| 30 | network would then connect the web server to the outside world to serve data to, but the outside world cannot
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| 31 | connect to the database. </p>
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| 32 | <p>To enable a host-only network interface for a virtual machine, do either of the following: </p>
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| 33 | <ul>
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| 34 | <li>
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| 35 | <p>Go to the <b outputclass="bold">Network</b> page in the virtual machine's <b outputclass="bold">Settings</b>
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| 36 | dialog and select an <b outputclass="bold">Adapter</b> tab. Ensure that the <b outputclass="bold">Enable
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| 37 | Network Adapter</b> check box is selected and choose <b outputclass="bold">Host-Only Adapter</b> for the <b
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| 38 | outputclass="bold">Attached To</b> field. </p>
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| 39 | </li>
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| 40 | <li>
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| 41 | <p>On the command line, use <userinput>VBoxManage modifyvm vmname --nic <varname>x</varname>
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| 42 | hostonly</userinput>. See <xref href="vboxmanage-modifyvm.dita"/>. </p>
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| 43 | </li>
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| 44 | </ul>
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| 45 | <p>For host-only networking, as with internal networking, you may find the DHCP server useful that is built into <ph
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| 46 | conkeyref="vbox-conkeyref-phrases/product-name"/>. This is enabled by default and manages the IP addresses in
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| 47 | the host-only network. Without the DHCP server you would need to configure all IP addresses statically. </p>
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| 48 | <ul>
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| 49 | <li>
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| 50 | <p>In <ph conkeyref="vbox-conkeyref-phrases/vbox-mgr"/> you can configure the DHCP server by choosing <b
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| 51 | outputclass="bold">File</b>, <b outputclass="bold">Tools</b>, <b outputclass="bold">Network Manager</b>. The
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| 52 | Network Manager window lists all host-only networks which are presently in use. Select the network name and
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| 53 | then use the <b outputclass="bold">DHCP Server</b> tab to configure DHCP server settings. See <xref
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| 54 | href="network-manager.dita#network-manager"/>. </p>
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| 55 | </li>
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| 56 | <li>
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| 57 | <p>Alternatively, you can use the <userinput>VBoxManage dhcpserver</userinput> command. See <xref
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| 58 | href="vboxmanage-dhcpserver.dita"/>. </p>
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| 59 | </li>
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| 60 | </ul>
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| 61 | <note>
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| 62 | <p>On Linux and macOS hosts the number of host-only interfaces is limited to 128. There is no such limit for
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| 63 | Oracle Solaris and Windows hosts. </p>
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| 64 | </note>
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| 65 | <p>On Linux, macOS and Solaris <ph conkeyref="vbox-conkeyref-phrases/product-name"/> will only allow IP addresses in
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| 66 | 192.168.56.0/21 range to be assigned to host-only adapters. For IPv6 only link-local addresses are allowed. If
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| 67 | other ranges are required, they can be enabled by creating <filepath>/etc/vbox/networks.conf</filepath> and
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| 68 | specifying allowed ranges there. For example, to allow 10.0.0.0/8 and 192.168.0.0/16 IPv4 ranges as well as
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| 69 | 2001::/64 range put the following lines into <filepath>/etc/vbox/networks.conf</filepath>: </p>
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| 70 | <pre xml:space="preserve"> * 10.0.0.0/8 192.168.0.0/16
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| 71 | * 2001::/64
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| 72 | </pre>
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| 73 | <p>Lines starting with the hash <userinput>#</userinput> are ignored. The following example allows any addresses,
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| 74 | effectively disabling range control: </p>
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| 75 | <pre xml:space="preserve"> * 0.0.0.0/0 ::/0
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| 76 | </pre>
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| 77 | <p>If the file exists, but no ranges are specified in it, no addresses will be assigned to host-only adapters. The
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| 78 | following example effectively disables all ranges: </p>
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| 79 | <pre xml:space="preserve"> # No addresses are allowed for host-only adapters
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| 80 | </pre>
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| 81 | </body>
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| 82 |
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| 83 | </topic>
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