Get KVM working on Debian

sudo apt-get install qemu-kvm libvirt-bin
# Add your user to the libvirt, then logout / log back in
sudo usermod -a -G libvirt $USER

# If not already done, disable network-manager (don't forget to configure your
# usually used interfaces)
sudo service network-manager stop
echo "manual" | sudo tee /etc/init/network-manager.override
# backup your interfaces file and change it to make it look that way if your IP
# configuration is static on eth0.
ifdown eth0
sudo mv /etc/network/interfaces /etc/network/interfaces.$(date +'%Y%m%d')
# THE NEXT COMMANDS SHOULD BE EXECUTED AS ROOT!
cat << __EOF__ > /etc/network/interfaces
# The loopback network interface
auto lo
iface lo inet loopback
# br0 configuration
auto br0
iface br0 inet static
  address 192.168.1.2
  netmask 255.255.255.0
  gateway 192.168.1.1
  bridge_ports eth0
  # Can generate a "set forward dealy: numeric value out of range" warning.
  # If you exeprience issues with passing DHCP to/from guest machines, put that
  # parameter to "off".
  bridge_stp on
  bridge_maxwait 0
  bridge_fd 0
__EOF__
ifup br0
# Then setup your sysctl parameters
cat << __EOF__ >> /etc/sysctl.conf
net.bridge.bridge-nf-call-ip6tables = 0
net.bridge.bridge-nf-call-iptables = 0
net.bridge.bridge-nf-call-arptables = 0
__EOF__
sysctl -p /etc/sysctl.conf
# Ensure the sysctl.conf is correctly loaded on boot and iptable is correctly
# configured (if you are managing it out of this file, just ignore that.
sudo cp /etc/rc.local /etc/rc.local.$(date +'%Y%m%d')
cat << __EOF__ > /etc/rc.local
#!/bin/sh -e
sbin/sysctl -p /etc/sysctl.conf
iptables -A FORWARD -p tcp --tcp-flags SYN,RST SYN -j TCPMSS --clamp-mss-to-pmtu
exit 0
__EOF__
iptables -A FORWARD -p tcp --tcp-flags SYN,RST SYN -j TCPMSS --clamp-mss-to-pmtu

sudo virsh net-autostart default
sudo virsh net-start default
# Now the following command should say that the defailt interface is active
sudo virsh net-list --all
# And the virbr0 interface should now appear in the following command output
sudo brctl show
# THEN EXECUTE THIS AS ROOT!
echo "net.ipv4.ip_forward = 1" >> /etc/sysctl.conf

sudo service libvirtd start

# View only machines owned by your session if non-root user
virsh list --all
# View all virtual machines of the system as non-root user
virsh --connect qemu:///system list --all
# Or:
LIBVIRT_DEFAULT_URI=qemu:///system virsh list --all
# To connect to vritualbox channel
virsh --connect vbox:///session list --all

VM_NAME=myVM01
virt-install --connect qemu:///system \
  --virt-type=kvm \
  --name $VM_NAME \
  --ram 512 \
  --vcpus=1 \
  --os-variant=rhel6 \
  --cdrom=Downloads/CentOS-6.5-x86_64-minimal.iso \
  --disk path=/var/lib/libvirt/images/${VM_NAME}_disk1.img,bus=sata,size=5 \
  --network network=default