Hi, First, thx for the reply. I follow your advises but I am still not able to use dbus. This is my configuration and the result: - I am launching dbus-daemon.exe --system in a system service (using CreateProcess). So in task manager I can see that the user name of the dbus-daemon process is "SYSTEM" (because of system service) - then I open a console and I type: set DBUS_SYSTEM_BUS_ADDRESS=tcp:host=localhost,port=12434 - then I run: dbus-send --print-reply --system --dest="org.freedesktop.DBus" /org/freedesktop /DBus/Introspectable org.freedesktop.DBus.Introspectable.Introspect -> the result: ------ Family none Failed to open connection to system message bus: Did not receive a reply. Possib le causes include: the remote application did not send a reply, the message bus security policy blocked the reply, the reply timeout expired, or the network con nection was broken. ----- I get the same result with or without typing: set DBUS_SYSTEM_BUS_ADDRESS=tcp:host=localhost,port=12434 But if I am using CreateProcessAsUser instead of CreateProcess (in the service run), in order to have "Administrator" as the user name associated with the dbus-daemon process, then it works. So I still cannot use dbus with severals users. Anyway, the result is at least better than using --session. Here it seems that something is not correct (for my needs) in the system.conf file. So here is the system.conf file I am using: ----------------------------------------------------------------------------------------------------------------------   <!DOCTYPE busconfig PUBLIC "-//freedesktop//DTD D-BUS Bus Configuration 1.0//EN" "<a href="http://www.freedesktop.org/standards/dbus/1.0/busconfig.dtd">http://www.freedesktop.org/standards/dbus/1.0/busconfig.dtd</a>"> <busconfig>  <type>system</type>  <user>Administrator</user>  <fork/>  <pidfile>/dbus-pid</pidfile>  <auth>EXTERNAL</auth>  <listen>tcp:host=localhost,port=12434</listen> <policy context="default">  <deny send_interface="*"/> <deny receive_interface="*"/> <deny own="*"/>  <allow user="*"/>   <allow send_destination="org.freedesktop.DBus"/> <allow receive_sender="org.freedesktop.DBus"/>  <allow send_requested_reply="true"/> <allow receive_requested_reply="true"/> </policy>  <includedir>system.d</includedir>  <include ignore_missing="yes">system-local.conf</include> <include if_selinux_enabled="yes" selinux_root_relative="yes">contexts/dbus_contexts</include> </busconfig> ---------------------------------------------------------------------------------------------------------------------- Any help would be much appreciated. Sincerely Julien <div class="gmail_quote">2009/11/19 Ralf Habacker <<a href="mailto:ralf.habacker@freenet.de">ralf.habacker@freenet.de</a>> <blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;"> Julien Isorce schrieb:<div class="im"> <blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;"> Hi, I isolated the problem I am facing to: If I run the dbus-daemon with a userA and if I run dbus-send with a userB then the result is the same as if the dbus-daemon was not running (so it fails) (it's ok if the 2 users are the same) </blockquote></div> By default the dbus library and the daemon provides a session bus which is user specific and only accessable by the same user. In your case you need to run dbus-daemon as system bus by dbus-daemon --system then set an environment variable to the recent system bus address (see <listen> statement in <dbus-install-root>/etc/system.conf for details) set DBUS_SYSTEM_BUS_ADDRESS=tcp:host=localhost,port=12434 and run for example qdbus --system to get a list of possible connections. In my case this is :1.6 :1.9 org.freedesktop.DBus dbus-send should then work also. Regards Ralf </blockquote></div>