/lib/systemd/system/libvirtd.socket is in libvirt-daemon-system 1.2.9-9+deb8u5.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 | [Socket]
ListenStream=/var/run/libvirt/libvirt-sock
ListenStream=/var/run/libvirt/libvirt-sock-ro
; The following settings must match libvirtd.conf file in order to
; work as expected because libvirtd can't change them later.
; SocketMode=0777 is safe only if authentication on the socket is set
; up. For further information, please see the libvirtd.conf file.
SocketMode=0777
SocketUser=root
SocketGroup=root
|