[vdsm] why password is needed in virsh after vdsm is installed?

[xiaxia347os]

Hello, guys
  after VDSM is installed, when I want to use virsh to list VMs on local host,
it prompt to input password and username. What could I do to make the connection
automatically succeed instead of input username and password interactively?
  By the way, I am also wondering which authentication method is used for libvirt
and vm migration in VDSM, I'd like to try these method for another usercase.

Best Regards.

Wenchao Xia