Virtualization


KVM: How to configure a bridge connection in Ubuntu 11.10 2

Make the file : /etc/network/interfaces  look something like this (make changes only to br0, add it if not there and to the device that you want to bridge with, we used eth1):

# This file describes the network interfaces available on your system
# and how to activate them. For more information, see interfaces(5).

# The loopback network interface
auto lo
iface lo inet loopback

# The primary network interface
auto eth0
iface eth0 inet dhcp

auto eth1
iface eth1 inet dhcp

# Building a bridge to be used by the Virtual Machines
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 eth1
        bridge_fd 9
        bridge_hello 2
        bridge_maxage 12
        bridge_stp off

Then issue: sudo /etc/init.d/networking restart
If you get:

* Running /etc/init.d/networking restart is deprecated because it may not enable again some interfaces
 * Reconfiguring network interfaces...                                                                                                                                                    RTNETLINK answers: File exists
ssh stop/waiting
ssh start/running, process 11489

Waiting for br0 to get ready (MAXWAIT is 20 seconds).
RTNETLINK answers: File exists
Failed to bring up br0.                        [ OK ]

Try bringing down the device to be bridged (eth1) like this: sudo  ifdown eth1 and then issue sudo /etc/init.d/networking restart again.
After that enable it the device again again like this: sudo  ifup eth1
If this doesn’t worked try restarting the machine, worked for us.

When properly configured ifconfig should result to something similar as this:

br0       Link encap:Ethernet  HWaddr 00:1a:64:67:d3:86  
          inet addr:192.168.0.10  Bcast:192.168.0.255  Mask:255.255.255.0
          inet6 addr: fe80::21a:64ff:fe67:d386/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:1752 errors:0 dropped:0 overruns:0 frame:0
          TX packets:18 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0
          RX bytes:136973 (136.9 KB)  TX bytes:1500 (1.5 KB)

eth0      Link encap:Ethernet  HWaddr 00:1a:64:67:d3:84  
          inet addr:10.16.20.60  Bcast:10.16.20.63  Mask:255.255.255.224
          inet6 addr: fe80::21a:64ff:fe67:d384/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:91218 errors:0 dropped:0 overruns:0 frame:0
          TX packets:51796 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:123551183 (123.5 MB)  TX bytes:4754458 (4.7 MB)
          Interrupt:16 Memory:ce000000-ce012800

eth1      Link encap:Ethernet  HWaddr 00:1a:64:67:d3:86  
          inet addr:10.16.20.33  Bcast:10.16.20.63  Mask:255.255.255.224
          UP BROADCAST RUNNING PROMISC MULTICAST  MTU:1500  Metric:1
          RX packets:2605 errors:0 dropped:48 overruns:0 frame:0
          TX packets:38 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:321878 (321.8 KB)  TX bytes:3490 (3.4 KB)
          Interrupt:17 Memory:ca000000-ca012800

lo        Link encap:Local Loopback  
          inet addr:127.0.0.1  Mask:255.0.0.0
          inet6 addr: ::1/128 Scope:Host
          UP LOOPBACK RUNNING  MTU:16436  Metric:1
          RX packets:129 errors:0 dropped:0 overruns:0 frame:0
          TX packets:129 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0
          RX bytes:17588 (17.5 KB)  TX bytes:17588 (17.5 KB)

virbr0    Link encap:Ethernet  HWaddr b6:ae:8d:e0:06:c3  
          inet addr:192.168.122.1  Bcast:192.168.122.255  Mask:255.255.255.0
          UP BROADCAST MULTICAST  MTU:1500  Metric:1
          RX packets:0 errors:0 dropped:0 overruns:0 frame:0
          TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0
          RX bytes:0 (0.0 B)  TX bytes:0 (0.0 B)

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Ubuntu 11.10 (Oneiric Ocelot): Installing KVM 2

Without any additional comments, we managed to install KVM over a fresh installation of Ubuntu 11.10 (Oneiric Ocelot).

To do this we installed the following packages from the repositories and added our user to the libvirtd group.

We called kvm-ok to make sure that our hardware supports KVM properly and thus having better performance.
Installation Commands:

sudo apt-get install kvm libvirt-bin
sudo adduser $USER libvirtd
sudo apt-get install virt-viewer
sudo apt-get install python-vm-builder
sudo apt-get install bridge-utils
sudo apt-get install virtinst #for cloning

After these we created a virtual machine with the following command:

sudo vmbuilder kvm ubuntu --suite oneiric --flavour virtual --arch amd64 --mem 1024 --cpus 2 -o --libvirt qemu:///system --ip 192.168.0.100 --hostname uranus --part vmbuilder.partition --user userName --name MyName MySurname --pass myPassword --addpkg unattended-upgrades --addpkg acpid --addpkg nano

where in general, what it does is, create an Ubuntu Oneiric Ocelot JeOS virtual machine that has an AMD64 architecture, 1GB of RAM, 2 Virtual CPUs, it’s name is uranus, has a user with the username userName, has pre-installed some applications like nano and enabled automatic updates for the system.


How to setup DNS service for DHCP-enabled KVM guests

So you’ve set up KVM on your machine and you have installed a few guests to run on top, now it’s the time to access them.

Since KVM can run without a GUI, you might want to control these guests from the command line. But, how can you do it if you do not know the IP of the guests?

You can either connect to the guest using virt-viewer:

virt-viewer -c qemu:///system $MACHINE &

which requires more bandwidth since it will open up a VNC session.

Or, use ssh to connect using the guest’s name, like this:

ssh $MACHINE

which doesn’t require that you know the IP beforehand.

To achieve this, access guest machines using their hostname only, you can do the following: Edit /etc/resolv.conf and add the line nameserver 192.168.122.1 right after the search entries .

Your file should look something like this afterwards:
domain in.bytefreaks.net
search in.bytefreaks.net
nameserver 192.168.122.1
nameserver 194.44.13.20
nameserver 194.44.13.58
nameserver 194.44.13.11

Then you are ready to go! No restarts needed no extra steps.

NOTES:

  • After restarting (and some times periodically), the /etc/resolv.conf file will return to its original form because it is updating each time you restart the host machine from data it gets via the network DHCP server.
  • For this tutorial to work as is, your host machine needs to have the virtual IP 192.168.122.1 (the default IP of your host in libvirt — NOT THE IP of eth0, it’s a totally different thing). If you have a different libvirt IP use that one in the /etc/resolv.conf file.
  • Use your host’s IP as your first nameserver in /etc/resolv.conf to achieve name resolution for your guests.


Oracle VirtualBox: Enable eth0 on backtrack4 / enable default ethernet card on backtrack

ifup eth0

*INFO: The default Ethernet device is disabled on boot but it can easily be enabled by just issuing the above command. (You still need to configure it depending on your system’s structure). In order to activate the Ethernet card you need to call the above command from the Terminal.