Hetzner - KVM - libvirt - Ubuntu walkthrough to routed network for VMs
Kernel Virtual Machines
The target of this article is to help people who have a dedicated server in Hetzner and want to run VMs through KVM and libvirt on it.
We assume that you:
- have a dedicated server which runs Ubuntu
- have ordered a subnet - or an additional IP
- want to run Ubuntu on VMs
install these packages in the host server
bridge-utils kvm libvirt-bin xauth x11-apps qemu-kvm virtinst virt-viewer libcap2-bin
now the setcap
setcap cap_net_admin=ei /usr/bin/qemu-system-x86_64
adduser {your_username} kvm
open the file
/etc/security/capability.conf
and add the following line in it
cap_net_admin YOUR_USERNAME
Now make backup of these files as you are going to edit them.
sudo cp /etc/sysctl.conf /etc/sysctl.conf.bak sudo cp /etc/network/interfaces /etc/network/interfaces.bak
ok, now open /etc/sysctl.conf and uncomment these lines
#net.ipv4.conf.all.rp_filter=1 #net.ipv4.ip_forward=1 #net.ipv6.conf.all.forwarding=1
now let's make some directories
sudo mkdir /var/VMs sudo mkdir /var/VMs/ISOs sudo mkdir /var/VMs/VHDs
navigate to /var/VMs/ISOs and wget ubuntu server .iso image, make sure in the vminstallation.sh script the name meets this .ISO
now create the xml file for the network
nano /root/hetzner.xml
and add the following content. Please note this "your_IP_from_subnet", there put your subnet IP.
<network> <name>Hetzner</name> <forward dev='eth0' mode='route'/> <bridge name='virbr2' stp='off' forwardDelay='0' /> <ip address='<your_IP_from_subnet>' netmask='255.255.255.224'/> </network>
join it to virsh
virsh net-define /root/hetzner.xml
and make it autostart
virsh net-autostart Hetzner
ok, now let's take care the file /etc/network/interfaces
open it and make it like this, (note: replace XX:YY with yours IP)
### Hetzner Online AG - installimage
# Loopback device:
auto lo
iface lo inet loopback
# device: eth0
auto eth0
iface eth0 inet static
address {YOUR_MAIN_IP}
broadcast {YOUR_BROADCAST_IP, this means leave it as it is}
netmask 255.255.255.255
gateway {YOUR_GATEWAY_IP, this means leave it as it is}
pointopoint {GATEWAY_IP, here add your GATEWAY_IP}
# default route to access subnet
up route add -net {LEAVE_IT_AS_IT_IS_IP} netmask 255.255.255.224 gw {GATEWAY_IP} eth0
# ip addr add {additional IP}/32 dev eth0 uncomment this line if you are going to use additional IP and NOT subnet IPs
iface eth0 inet6 static
address 2a01:4f8:XX:YY::2
netmask 128
gateway fe80::1
auto virbr2
iface virbr2 inet static
address {YOUR_MAIN_IP}
netmask 255.255.255.255
bridge_ports none
bridge_stp off
bridge_fd 0
pre-up brctl addbr virbr2 # comment this line if you are giong to use additional IP and NOT subnet IPs
up ip route add {YOUR_ADDITIONAL_OR_FROM_SUBNET}/32 dev virbr2
down ip route del {YOUR_ADDITIONAL_IP_FROM_SUBNET}/32 dev virbr2 # comment this line if you are giong to use additional IP and NOT subnet IPs
iface virbr2 inet6 static
address 2a01:4f8:XX:YY::2
netmask 64
note. by default to edit virsh files it is done through VIM editor, if you like nano editor better then add the following lines in the file.bashrc
alias virsh='EDITOR=/usr/bin/nano virsh'
and to take effect immediately
source .bashrc
reboot host now
now let's create the script that will do the installation of the guest server.
sudo nano vminstall.sh
and add the following
#!/bin/bash virt-install --name 12.04 --file /var/VMs/VHDs/12.04 --vnc --cdrom /var/VMs/ISOs/ubuntu-12.04.4-server-amd64.iso --ram 1024 --connect qemu:///system --file-size 5 --nonsparse --network network=Hetzner --os-type=linux --os-variant=ubuntuprecise
note that the the above script will create the guest with the following characteristics
-name=12.04-the downloaded distro is ubuntu-12.04.4-server-amd64.iso
-1024MB RAM will be applied
-5GB in the hard disk
but you can make your own decision, just check out this manual http://linux.die.net/man/1/virt-install
open a terminal and connect to your server with X forwarding {ssh -X} with that way
virt-viewer --connect qemu:///system 12.04
and from another terminal start the operation
virsh start 12.04
now it is time to execute the installation script, do it and pass through the installation steps of the Ubuntu server. Somewhere in the middle it will say that the network is unconfigured, leave it as it is and go on to finish the installation.
When finished (in the guest OS) edit the file /etc/network/interfaceswith the following
# 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
auto eth0
iface eth0 inet static
address {YOUR_SUBNET_IP}
broadcast {THE_BROADCAST_IP_YOU_WILL_FIND_IT_IN_ROBOT_HETZNER}
netmask 255.255.255.255
pointopoint {YOUR_MAIN_SERVER_IP}
gateway {YOUR_MAIN_SERVER_IP}
dns-nameservers 213.133.98.98 213.133.99.99
iface eth0 inet6 static
address 2a01:4f8:XX:YY::4
netmask 64
gateway 2a01:4f8:XX:YY::2
now (in the guest OS) edit the file /etc/hosts
127.0.0.1 localhost
{SUBNET_IP} 1204guest ##{THIS IS MY HOSTNAME}
# The following lines are desirable for IPv6 capable hosts
::1 ip6-localhost ip6-loopback
fe00::0 ip6-localnet
ff00::0 ip6-mcastprefix
ff02::1 ip6-allnodes
ff02::2 ip6-allrouters
ok we are almost done, run these commands for the network to take effect.
sudo ifdown eth0 sudo ifup etho
OK that was it, now update-upgrade and install openssh-server in your brand new instance
NOTE: don't forget to make your new instance autostart,
in the host system run
virsh autostart 12.04
references:
http://libvirt.org/sources/virshcmdref/html-single/
http://linux.die.net/man/1/virt-install
http://wiki.hetzner.de/index.php/Hauptseite/en
http://webmodelling.com/webbits/ubuntu/ubuntu-virtualization.aspx
This work is licensed under a Creative Commons Attribution 4.0 International License.
