There are a few different ways to allow a virtual machine access to the external network. The default virtual network configuration is usermode networking, which uses the SLIRP protocol and traffic is NATed through the host interface to the outside network.

To enable external hosts to directly access services on virtual machines a bridge needs to be configured. This allows the virtual interfaces to connect to the outside network through the physical interface, making them appear as normal hosts to the rest of the network. To setup a bridge interface edit /etc/network/interfaces and either comment or replace the existing config with:

auto lo iface lo inet loopback auto br0 iface br0 inet static address 192.168.0.10 network 192.168.0.0 netmask 255.255.255.0 broadcast 192.168.0.255 gateway 192.168.0.1 bridge_ports eth0 bridge_fd 9 bridge_hello 2 bridge_maxage 12 bridge_stp off

Now restart networking and your virtual machines that are managed by libvirt will appear on the network the same as physical hosts:

sudo /etc/init.d/networking restart

If setting up a bridge interface using Ubuntu Desktop Edition, or if dhcdbd is installed, the dhcdbd daemon will need to be stopped and disabled.

After configuring the bridge in /etc/network/interfaces, shutdown dhcdbd by:

sudo /etc/init.d/dhcdbd stop

Now to disable it from starting on boot enter:

sudo update-rc.d -f dhcdbd remove

To install the necessary packages, from a terminal prompt enter:

sudo apt-get install kvm libvirt-bin

After installing libvirt-bin, the user used to manage virtual machines will need to be added to the libvirtd group. Doing so will grant the user access to the advanced networking options.

In a terminal enter:

sudo adduser $USERNAME libvirtd

You are now ready to install a Guest operating system. Installing a virtual machine follows the same process as installing the operating system directly on the hardware. You either need a way to automate the installation, or a keyboard and monitor will need to be attached to the physical machine.

In the case of virtual machines a Graphical User Interface (GUI) is analogous to using a physical keyboard and mouse. Instead of installing a GUI the virt-viewer application can be used to connect to a virtual machine's console using VNC. See the section called “Virtual Machine Viewer” for more information.

There are several ways to automate the Ubuntu installation process, for example using preseeds, kickstart, etc. Refer to the Ubuntu Installation Guide for details.

Yet another way to install an Ubuntu virtual machine is to use ubuntu-vm-builder. ubuntu-vm-builder allows you to setup advanced partitions, execute custom post-install scripts, etc. For details see the section called “ubuntu-vm-builder”

virt-install is part of the python-virtinst package. To install it, from a terminal prompt enter:

sudo apt-get install python-virtinst

There are several options available when using virt-install. For example:

sudo virt-install -n web_devel -r 256 -f web_devel.img -s 4 -c jeos.iso --accelerate --vnc --noautoconsole

After launching virt-install you can connect to the virtual machine's console either locally using a GUI or with the virt-viewer utility.

The virt-clone application can be used to copy one virtual machine to another. For example:

sudo virt-clone -o web_devel -n database_devel -f /path/to/database_devel.img --connect=qemu:///system

Also, use -d or --debug option to help troubleshoot problems with virt-clone.

The virt-viewer application allows you to connect to a virtual machine's console. virt-viewer does require a Graphical User Interface (GUI) to interface with the virtual machine.

To install virt-viewer from a terminal enter:

sudo apt-get install virt-viewer

Once a virtual machine is installed and running you can connect to the virtual machine's console by using:

virt-viewer qemu:///system web_devel

Similar to virt-manager, virt-viewer can connect to a remote host using SSH with key authentication, as well:

virt-viewer -c qemu+ssh://virtnode1.mydomain.com/system web_devel

Be sure to replace web_devel with the appropriate virtual machine name.

If configured to use a bridged network interface you can also setup SSH access to the virtual machine. See the section called “OpenSSH Server” and the section called “Virtual Networking” for more details.