avahi-0.6.31/avahi-daemon/avahi-dbus.conf

<!DOCTYPE busconfig PUBLIC
          "-//freedesktop//DTD D-BUS Bus Configuration 1.0//EN"
          "http://www.freedesktop.org/standards/dbus/1.0/busconfig.dtd">
<busconfig>

  <!-- Only root or user avahi can own the Avahi service -->
  <policy user="avahi">
    <allow own="org.freedesktop.Avahi"/>
  </policy>
  <policy user="root">
    <allow own="org.freedesktop.Avahi"/>
  </policy>

  <!-- Allow anyone to invoke methods on Avahi server, except SetHostName -->
  <policy context="default">
    <allow send_destination="org.freedesktop.Avahi"/>
    <allow receive_sender="org.freedesktop.Avahi"/>

    <deny send_destination="org.freedesktop.Avahi"
          send_interface="org.freedesktop.Avahi.Server" send_member="SetHostName"/>
  </policy>

  <!-- Allow everything, including access to SetHostName to users of the group "netdev" -->
  <policy group="netdev">
    <allow send_destination="org.freedesktop.Avahi"/>
    <allow receive_sender="org.freedesktop.Avahi"/>
  </policy>
  <policy user="root">
    <allow send_destination="org.freedesktop.Avahi"/>
    <allow receive_sender="org.freedesktop.Avahi"/>
  </policy>
</busconfig>