KVM for Kernel-based Virtual Machine is an open source software is  a fully virtualization   support for Linux on x86 hardware.  Cloudmin's installer can be used on CentOS, Fedora, Debian and Ubuntu operating systems. KVM can run multiple virtual machine running with Linux and windows images. We can easily install and managed your virtual machines. Each virtual machine has separate virtual hardware: network card, disk, RAM, Cores,etc.

You need to check your hardware configuration whether is sutable for virtuallization and can check in a command,
            

# egrep -i 'svm|vmx' --color=auto /proc/cpuinfo


flags: fpu vme de pse36  lm constant_tsc nx pdpe1gb arch_perfmon clflush dts acpi mmx fxsr sse rdtscp pebs bts rep_good xtopology sse2 pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat  ss ht tm pbe syscall nonstop_tsc aperfmperf pni pclmulqdq dtes64 monitor ds_cpl "vmx" smx est tm2 ssse3 cx16 xtpr pdcm pcid dca sse4_1 sse4_2 x2apic popcnt tsc_deadline_timer aes xsave avx f16c rdrand lahf_lm ida arat epb xsaveopt pln pts dts tpr_shadow vnmi flexpriority ept vpid fsgsbase smep erms


On BIOS Settings you have to set virtuallization Technology is being Enabled,
 
# cd /root

# wget http://cloudmin.virtualmin.com/gpl/scripts/cloudmin-kvm-redhat-install.sh

Give execute permission using chmod command,
 
# chmod +x cloudmin-kvm-redhat-install.sh

Now execute the shell script to install KVM with cloudmin,
 
# ./cloudmin-kvm-redhat-install.sh


*******************************************************************************

*         Welcome to the Cloudmin GPL for KVM installer, version 1.1         *

*******************************************************************************

 Operating systems supported by this installer are:



 Fedora Core 3-12 on i386 and x86_64

 CentOS and RHEL 3-7 on i386 and x86_64



 If your OS is not listed above, this script will fail (and attempting

 to run it on an unsupported OS is not recommended, or...supported).

 Continue? (y/n) y

...

...

Cloudmin GPL has been successfully installed.


You can login to Cloudmin at :  https://localhost.localdomain:10000/  

or use your system IP  at     :  https://192.168.1.1:10000/


Error 1 :

You may get the below errors while installtalling KVM,

SELINUXTYPE=targeted
This system cannot be a KVM host : No bridge interfaces like br0 were found,

also, check using below commands,
 
# sudo modprobe kvm-intel


FATAL: Error inserting kvm_intel (/lib/modules/2.6.32-358.el6.x86_64/kernel/arch/x86/kvm/kvm-intel.ko): Operation not supported


Solution :

You need to check your BIOS setting : Virtualization Technology is enabled

Error 2 :

Network Bridge Connection: https://192.168.1.1:10000/
 
# ifup nc1
Error: Connection activation failed: Master connection not found or invalid
# ifup br0
Error: Connection activation failed: Failed to determine connection's virtual interface name


Solution :

You need to check enabled the IP Forward,
vim /etc/sysctl.conf
net.ipv4.ip_forward = 0

to
net.ipv4.ip_forward = 1

Save the configuration,
 
# sysctl -w

# sysctl -p


net.ipv4.ip_forward = 1

net.ipv4.conf.default.rp_filter = 1

net.ipv4.conf.default.accept_source_route = 0

kernel.sysrq = 0

kernel.core_uses_pid = 1

net.ipv4.tcp_syncookies = 1

net.bridge.bridge-nf-call-ip6tables = 0

net.bridge.bridge-nf-call-iptables = 0

net.bridge.bridge-nf-call-arptables = 0

kernel.msgmnb = 65536

kernel.msgmax = 65536

kernel.shmmax = 58112426734

kernel.shmall = 5224769276


Solution 2 :

Also check in your setup-kvm-bridge.pl file line number is  34

/usr/libexec/webmin/server-manager/setup-kvm-bridge.pl

$br_name and $eth_name is connect format,

$br_name = "br0";
$eth_name = "eth0";

to

$br_name = "br0";
$eth_name = "nc1";

Solution 3 :

You need to disabled SELINUX 

 Finally restart your network and check your network configuration,
 
#/etc/init.d/network restart

# ifconfig