| 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_internal">
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| 4 | <title>Internal Networking</title>
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| 5 |
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| 6 | <body>
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| 7 | <p>Internal Networking is similar to bridged networking in that the VM can directly communicate with the outside
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| 8 | world. However, the outside world is limited to other VMs on the same host which connect to the same internal
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| 9 | network. </p>
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| 10 | <p>Even though technically, everything that can be done using internal networking can also be done using bridged
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| 11 | networking, there are security advantages with internal networking. In bridged networking mode, all traffic goes
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| 12 | through a physical interface of the host system. It is therefore possible to attach a packet sniffer such as
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| 13 | Wireshark to the host interface and log all traffic that goes over it. If, for any reason, you prefer two or more
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| 14 | VMs on the same machine to communicate privately, hiding their data from both the host system and the user,
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| 15 | bridged networking therefore is not an option. </p>
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| 16 | <p>Internal networks are created automatically as needed. There is no central configuration. Every internal network
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| 17 | is identified simply by its name. Once there is more than one active virtual network card with the same internal
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| 18 | network ID, the <ph conkeyref="vbox-conkeyref-phrases/product-name"/> support driver will automatically
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| 19 | <i>wire</i> the cards and act as a network switch. The <ph conkeyref="vbox-conkeyref-phrases/product-name"/>
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| 20 | support driver implements a complete Ethernet switch and supports both broadcast/multicast frames and promiscuous
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| 21 | mode. </p>
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| 22 | <p>In order to attach a VM's network card to an internal network, set its networking mode to Internal Networking.
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| 23 | There are two ways to accomplish this: </p>
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| 24 | <ul>
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| 25 | <li>
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| 26 | <p>Use the VM's <b outputclass="bold">Settings</b> window in <ph conkeyref="vbox-conkeyref-phrases/vbox-mgr"/>.
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| 27 | In the <b outputclass="bold">Network</b> category of the Settings window, select <b outputclass="bold"
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| 28 | >Internal Network</b> from the drop-down list of networking modes. Select the name of an existing internal
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| 29 | network from the drop-down list below, or enter a new name into the <b outputclass="bold">Name</b> field. </p>
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| 30 | </li>
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| 31 | <li>
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| 32 | <p>Use the command line, for example: </p>
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| 33 | <pre xml:space="preserve">VBoxManage modifyvm "VM name" --nic<x> intnet</pre>
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| 34 | <p>
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| 35 | Optionally, you can specify a network name with the command:
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| 36 | </p>
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| 37 | <pre xml:space="preserve">VBoxManage modifyvm "VM name" --intnet<x> "network name"</pre>
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| 38 | <p>If you do not specify a network name, the network card will be attached to the network
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| 39 | <codeph>intnet</codeph> by default. </p>
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| 40 | </li>
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| 41 | </ul>
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| 42 | <p>Unless you configure the virtual network cards in the guest operating systems that are
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| 43 | participating in the internal network to use static IP addresses, you may want to use the DHCP
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| 44 | server that is built into <ph conkeyref="vbox-conkeyref-phrases/product-name"/> to manage IP addresses for the internal
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| 45 | network. See <xref href="vboxmanage-dhcpserver.dita"/>. </p>
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| 46 | <p>As a security measure, by default, the Linux implementation of
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| 47 | internal networking only allows VMs running under the same user ID
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| 48 | to establish an internal network. However, it is possible to
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| 49 | create a shared internal networking interface, accessible by users
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| 50 | with different user IDs.
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| 51 | </p>
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| 52 | </body>
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| 53 |
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| 54 | </topic>
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