Install Virtual Machines on Linux Dedicated Server

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For Ubuntu Server 14.04.x LTS

We show you how to install Ubuntu and KVM on your Server guest systems and make them accessible via a (separate) public IP.

The use of the Kernel-based Virtual Machine (KVM) makes sense, as KVM has been Ubuntu's officially supported (and preferred in the server area) virtualization solution since Ubuntu 8.04. The KVM kernel module has also been an official part of the Linux kernel since 2.6.20.

Step 1 Check prerequisites

Before you start the installation, make sure that your server meets the technical requirements for using KVM: KVM requires server hardware that supports virtualization at the hardware level. Use the following command to determine whether this is the case on your server:

egrep -c '(vmx|svm)' /proc/cpuinfo

If you get here a value greater than or equal to 1 as return value, everything is OK. If this is not the case, switch to another software - for example

If you want to set up guest systems with more than 2 GB RAM, you need a host system with 64bit kernel. Check as follows:

egrep -c ' lm ' /proc/cpuinfo

A"1" (or higher) means that you have a 64bit system. In the other case a new installation with a 64Bit image would be necessary.

Step 2 Install KVM

Install the required packages:

apt-get install qemu-kvm libvirt-bin ubuntu-vm-builder bridge-utils

Then you have to add your users to the groups kvm and libvirtd:

adduser `id -un` kvm 
adduser `id -un` libvirtd 

Since the change does not take effect until the next login, you now have to log off briefly and log on again.

Step 3 Install and configure guest system(s)

After you have completed the installation of KVM, you can set up the (first) guest (create others in the same way).

Step 3.1 Provide storage space

All current server images are equipped with the Logical Volume Manager (LVM). This makes it possible to create dynamically changeable partitions (logical volumes). In order to offer you the greatest possible flexibility, not all of your server's capacity is pre-partitioned when delivered. For example, the initial size of /var is only 4GB.

For example, the following command increases /var by 20GB (if you are using a server without an SSD option, replace"ssd" with"vg00"):

lvextend -L +20G /dev/ssd/var

Afterwards, the file system must be adjusted to the new size:

resize2fs /dev/ssd/var
Step 3.2 Installing VM and OS

There are a number of tools that simplify the setup of virtual machines. This guide uses the virt-inst tool included in the virtinst package:

apt-get install virtinst

It is important (see note at the beginning of this manual) that the VM is created with the network setting NAT, which should however correspond to the default setting. Check as follows:

virsh net-dumpxml default
<network connections='3'>
<forward mode='nat'>
<port start='1024' end='65535'/>
<bridge name='virbr0' stp='on' delay='0'/>
<ip address='' netmask=''>
<range start='' end=''/>

The following command creates a VM and connects you to it via serial console. There you can perform the installation of the guest system (here Ubuntu 14.04) started from the assigned image.

virt-install --name vm1 --ram 2048 --disk path=/var/lib/libvirt/images
/vm1.img,size=8 --vcpus 2 --os-type linux --os-variant ubuntutrusty --network
network=default --graphics none --console pty,target_type=serial --location /var/lib/libvirt
/boot/ubuntu-14.04-server-i386.iso --extra-args 'console=ttyS0,115200n8 serial'
Parameters meaning
name name of the VM
2048 MB main memory  
disk 8 GB total disk space (img)
vcpus 2 virtual cores for the VM
OS Type of operating system (Linux, ubuntutrusty)
--network Which network property, 'default' stands for NAT by default in this case (absolutely necessary!)
--graphics Possible graphic settings
the installation runs from the serial console  
--location the path to the ISO image

Before you make changes to the guest system, make sure that the VM is started automatically in the future. Exit the virtual console by pressing (Ctrl)+(+) and enter the following command on the host:

virsh -c qemu://system autostart vm1

Then use the following command to switch back to the guest system:

virsh console vm1
Step 3.3 Configuring the network (IPv4)

To make the guest system accessible via a public IP address, a few more changes on the guest and host systems are necessary.

Step 3.3.1 Guest settings

Note: Please replace the example IP with your address in the following steps (you manage your IP addresses in IONOS under Server > IP Addresses).

Create an Ethernet alias (e.g. eth0:0) with the public IPv4 address :

sudo vi /etc/network/interfaces
# 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 eth0:0
iface eth0:0 inet static
Step 3.3.2 Settings on the host

First activate IP forwarding in the kernel:

sudo sh -c "echo 1 /proc/sys/net/ipv4/ip forward"

Now the route to the virtual network is needed:

route add -host dev virbr0 

Finally, add the necessary firewall rules:

iptables -I FORWARD 1 -t filter -d -o virbr0 -j ACCEPT
iptables -I FORWARD 1 -t filter -s -i virbr0 -j ACCEPT

So that these settings are also active after the next restart, write them to rc.local as follows:

vi /etc/rc.local
while [ `ps -e | grep -c libvirtd` -lt 1 ]; do
sleep 1
sleep 10
# set up custom iptables rules.
iptables -I FORWARD 1 -t filter -d -o virbr0 -j ACCEPT
iptables -I FORWARD 1 -t filter -s -i virbr0 -j ACCEPT

# add static routes to the ip routing table

route add -host dev virbr0

) &amp;
exit 0
Step 3.4 Configuring the network (IPv6)

You can also make your guest systems available and/or via IPv6. The IPv6 subnet assigned to you can be found in IONOS under Server > IP Addresses.

The following steps show setup using the example of the subnet 2001:8d8:91d:bd00::/56.

Step 3.4.1 Settings on the host

Enable IPv6 forwarding by commenting out the line net.ipv6.conf.all.forwarding=1 in /etc/sysctl.conf:

vi /etc/sysctl.conf
# Uncomment the next line to enable packet forwarding for IPv6
# Enabling this option disables Stateless Address Autoconfiguration
# based on Router Advertisements for this host

Then the interfaces eth0 and virbr0 must be reconfigured. The addresses are then automatically distributed to the guest systems later.

For simplicity, eth0 gets the smallest possible address that the IPv6 subnet allows. In this example, 2001:08D8:091D:BD00:0000:0000:0000:0000:0001 :

vi /etc/network/interfaces
# 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
iface eth0 inet6 static
address 2001:08D8:091D:BD00:0000:0000:0000:0001
netmask 64
post-up ip -6 route add fe80::1 dev eth0
post-up ip -6 route add default via fe80::1 dev eth0
post-down ip -6 route del default via fe80::1 dev eth0
post-down ip -6 route del fe80::1 dev eth0

Before you edit virbr0, shut down the virtual network:

virsh net-destroy default

Now enter Virbr0 the smallest possible address of a new subnet. In the following example this is 2001:08D8:091D:BD01:0000:0000:0000:0000:0001 :

virsh net-edit default
<forward mode='nat'/>
<bridge name='virbr0' stp='on' delay='0'/>
<mac address='52:54:00:80:c9:68'/>
<ip address='' netmask=''>
<range start='' end=''/>
<ip family='ipv6' address='2001:08D8:091D:BD01:0000:0000:0000:00001' prefix='64'>

In order for a guest to receive an IPv6 address from this subnet, it must be restarted:

virsh -c qemu://system reboot <name> 

Attention, the guest system now has two IPv6 addresses! The configuration now looks like this, for example:

eth0 Link encap:Ethernet HWaddr 52:54:00:9a:17:3e
inet addr: Bcast: Mask:
inet6 addr: 2001:8d8:91d:bd01:8982:6203:5146:27e9/64 Scope:Global
inet6 addr: 2001:8d8:91d:bd01:5054:ff:fe9a:173e/64 Scope:Global
inet6 addr: fe80::5054:ff:fe9a:173e/64 Scope:Link
RX packets:18 errors:0 dropped:3 overruns:0 frame:0
TX packets:24 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:1811 (1.8 KB) TX bytes:2500 (2.5 KB)

The lower (line 4) in this example is the fixed IP address. This consists of the subnet[2001:8d8:91d:bd01] and a second part, which is derived from the hardware address. The upper IPv6 address is partially generated randomly. The guest system is now uniquely identifiable and accessible under both IP addresses. For the accessibility of e.g. web servers, the lower/fixed IP should be used.