KVM - Virtual Machine

KVM, Kernel-based Virtual Machine, is a hypervisor built into the Linux kernel. It is similar to Xen in purpose but much simpler to get running.

Setup

For ArchLinux,

And, yet an another good guide,

Can’t start KVM guest: “network ‘default’ is not active”?

First, confirm that the default network is indeed inactive:

sudo virsh net-list --all

If so, start the default network:

sudo virsh net-start default

Run the first command line again to see if it worked.

And, for autostart, I believe it is,

sudo virsh net-autostart default

Credit - askubuntu