Networking with VirtualBox
Network Address Translation
NAT mode gives you a quick and uncomplicated approach to breaking out of jail. After selecting NAT mode in the Connected to drop-down box, the virtual network card is assigned an address by a simulated DHCP server with a firewall that gives the virtual machine access to the outside world.
Figure 3 shows you how this works. In step one, the adapter in the virtual machine is automatically assigned an IP address by the integrated DHCP server, which normally assigns addresses in the 10.0.x.x. range.
![](/var/linux_magazin/storage/images/linux-magazine.com/issues/2008/90/network-in-a-box/figure-3/431066-1-eng-US/Figure-3_large.png)
As soon as the guest starts transmitting packets over the virtual wire, VirtualBox captures the packages and inserts the host system's IP address before sending them onto the Internet.
Although the configuration does not take long, this operating mode involves one functional drawback: IP address implementation (NAT) in combination with the internal firewall lets the guest system send data out into the world; however, the outside world, and the host, are kept out. The only exception here is remote desktop in the commercial version, or you can use VPN tools such as Openvpn to tunnel into the box.
Port Forwarding
In other words, it is impossible to encapsulate production servers in the virtual NAT machine in a meaningful way. Port forwarding gives you a workaround. VirtualBox listens on a port on the host system and forwards packages arriving at this port to a port on the selected virtual machine. From another machine's point of view, it seems that the service is available directly on the host.
Three VBoxManage commands enable port forwarding before launching the virtual machine:
VBoxManage setextradata "UbuntuVM" "VBoxInternal/Devices/pcnet/0/LUN#0/Config/myservice/Protocol" TCP VBoxManage setextradata "UbuntuVM" "VBoxInternal/Devices/pcnet/0/LUN#0/Config/myservice/GuestPort" 22 VBoxManage setextradata "UbuntuVM" "VBoxInternal/Devices/pcnet/0/LUN#0/Config/myservice/HostPort" 2222
This tells VirtualBox to forward all TCP connections for port 2222 on the host to port 22 on the guest. myservice is a freely assignable name, and UbuntuVM is the name of the virtual machine. If all of these values are empty when the command is called, VirtualBox will disable port forwarding again.
Host Interface
NAT with port forwarding entails noticeable organizational overhead. The administrator must open – and possibly secure – ports on the server; of course, you need to keep track of which ports are mapped to which services on which machine. Host Interface Networking mode gives you a more convenient approach to running a server on VirtualBox, although setting up this mode is quite tricky.
In Host Interface Networking mode, VirtualBox creates an additional virtual network card on the host – for example, vbox0 besides the familiar eth0. After setting up the new network card, VirtualBox uses a virtual cable to patch the connection to the simulated adapter on the guest system (Figure 4).
![](/var/linux_magazin/storage/images/linux-magazine.com/issues/2008/90/network-in-a-box/figure-4/431069-1-eng-US/Figure-4_large.png)
For productive applications, VirtualBox typically uses a bridge to connect the physical and virtual networks. This union acts like a single large network in interactions with the outside world.
To set this up, you first need to set up a virtual network interface for each guest on the host.
Buy this article as PDF
(incl. VAT)
Buy Linux Magazine
Subscribe to our Linux Newsletters
Find Linux and Open Source Jobs
Subscribe to our ADMIN Newsletters
Support Our Work
Linux Magazine content is made possible with support from readers like you. Please consider contributing when you’ve found an article to be beneficial.
![Learn More](https://www.linux-magazine.com/var/linux_magazin/storage/images/media/linux-magazine-eng-us/images/misc/learn-more/834592-1-eng-US/Learn-More_medium.png)
News
-
NVIDIA Released Driver for Upcoming NVIDIA 560 GPU for Linux
Not only has NVIDIA released the driver for its upcoming CPU series, it's the first release that defaults to using open-source GPU kernel modules.
-
OpenMandriva Lx 24.07 Released
If you’re into rolling release Linux distributions, OpenMandriva ROME has a new snapshot with a new kernel.
-
Kernel 6.10 Available for General Usage
Linus Torvalds has released the 6.10 kernel and it includes significant performance increases for Intel Core hybrid systems and more.
-
TUXEDO Computers Releases InfinityBook Pro 14 Gen9 Laptop
Sporting either AMD or Intel CPUs, the TUXEDO InfinityBook Pro 14 is an extremely compact, lightweight, sturdy powerhouse.
-
Google Extends Support for Linux Kernels Used for Android
Because the LTS Linux kernel releases are so important to Android, Google has decided to extend the support period beyond that offered by the kernel development team.
-
Linux Mint 22 Stable Delayed
If you're anxious about getting your hands on the stable release of Linux Mint 22, it looks as if you're going to have to wait a bit longer.
-
Nitrux 3.5.1 Available for Install
The latest version of the immutable, systemd-free distribution includes an updated kernel and NVIDIA driver.
-
Debian 12.6 Released with Plenty of Bug Fixes and Updates
The sixth update to Debian "Bookworm" is all about security mitigations and making adjustments for some "serious problems."
-
Canonical Offers 12-Year LTS for Open Source Docker Images
Canonical is expanding its LTS offering to reach beyond the DEB packages with a new distro-less Docker image.
-
Plasma Desktop 6.1 Released with Several Enhancements
If you're a fan of Plasma Desktop, you should be excited about this new point release.