Take a look at this WIKI article:
There are two buses commonly used: the session bus and the system bus. Either may be used by any application, depending on what it is doing.
- To monitor the session bus:
dbus-monitor - To monitor the system bus:
create a file /etc/dbus-1/system-local.conf, with these contents:
<!DOCTYPE busconfig PUBLIC "-//freedesktop//DTD D-Bus Bus Configuration 1.0//EN" "http://www.freedesktop.org/standards/dbus/1.0/busconfig.dtd"> <busconfig> <policy user="root"> <allow eavesdrop="true"/> <allow eavesdrop="true" send_destination="*"/> </policy> </busconfig> Reboot your machine to pick up the configuration changes. Simply reloading the DBus server configuration is not sufficient. For further info see this bug.
Now run dbus-monitor as root. You should be able to see all signals, method calls, and method replies.
sudo dbus-monitor --system When done debugging, it is wise to remove the policy snippet:
sudo rm /etc/dbus-1/system-local.conf