By default, Virtual Machine Manager on Linux (in my case on Fedora) will ask for root password before starting up. Every time I clicked on Applications -> System Tools -> Virtual Machine Manager password popup appeared no matter I'm the only user on my PC. If you have the same situation, here are few steps how to get rid of entering root password each time you start VM manager.
1) Open /etc/libvirt/libvirtd.conf file and uncomment two lines
With activation unix_sock_rw_perms line, change permission from 0770 to 0777:
# If not using PolicyKit and setting group ownership for access # control then you may want to relax this to: unix_sock_rw_perms = "0777"
And line auth_unix_rw should be activated (just remove comment):
# If the unix_sock_rw_perms are changed you may wish to enable # an authentication mechanism here auth_unix_rw = "none"
2) Restart libvirtd daemon
> service libvirtd restart
Now you should be able to start Virtual Machine Manager on your Linux desktop without entering a root password.