SIr, Regards. Thanks a ton for the reply. Thanks, Thanks, Thanks !!! That solved it !!! Following is the modified program, along with its output (just one quirk; as can be seen from the output, occassionally there are (spurious) 'AccessPointAdded' signals received, *with a blank SSID*. Don't know what the reason may be). Anyways, here is the program (connection-activation logic excluded) and output : ================================================================================ """ LEARNINGS : A system usually has only one (fixed) wireless device hardware. Thus, no callbacks for addition/removal of this device are triggered. (Can't thank you enough Sascha !!! :) :) ) However, this (single) hardware has the capacity to pair with multiple access-points. In Networkmanager (at least python APIs), each access-point is represented by its path, which serves as its key. Using this key, other properties (notably SSID) can be retreived. For a wired device, it again is fixed; thus no addition/removal callbacks (Thanks again Sascha). There is no concept of SSID; a wired device is just a medium for physical connection. Moreover, there is one-to-one correspondence for a wired-device, and the network. """ """ TESTS DONE :: a. Additon/Removal of USB Modem triggers corresponding callbacks. b. Addition/Removal of wireless access-points triggers callbacks. """ import dbus from dbus.mainloop.glib import DBusGMainLoop DBusGMainLoop(set_as_default=True) bus = dbus.SystemBus() """ The names have been designed, keeping in consistency of the nomenclature used in "add_signal_receiver" method. """ NM_BUS_NAME = 'org.freedesktop.NetworkManager' NM_PATH = '/org/freedesktop/NetworkManager' NM_DBUS_INTERFACE = 'org.freedesktop.NetworkManager' """ Note that the following is not specifically tied to Network Manager. """ DBUS_PROPS_DBUS_INTERFACE = 'org.freedesktop.DBus.Properties' """ Some more :) """ NM_DEVICE_DBUS_INTERFACE = 'org.freedesktop.NetworkManager.Device' NM_WIRED_DEVICE_INTERFACE = 'org.freedesktop.NetworkManager.Device.Wired' NM_WIFI_DEVICE_INTERFACE = 'org.freedesktop.NetworkManager.Device.Wireless' NM_ACCESS_POINT_DBUS_INTERFACE = 'org.freedesktop.NetworkManager.AccessPoint' class NMDbusPathProcessor: """ This class encapsulates functions, that would be used for processing any networkmanager-dbus-path. """ def get_nm_object(self, nm_dbus_path): """ returns dbus-object for the nm-dbus-path. """ return bus.get_object(NM_BUS_NAME, nm_dbus_path) def get_nm_props_interface(self, nm_dbus_path): """ returns the interface, encapsulating the nm-dbus-path. """ nm_object = self.get_nm_object(nm_dbus_path) return dbus.Interface(nm_object, DBUS_PROPS_DBUS_INTERFACE) nm_dbus_path_processor = NMDbusPathProcessor() class BaseTypeProcessor: """ This class is a virtual class; each subtype of which implements a particular hierarchy of NetworkManager architecture. (or kind of :) ) """ def __init__(self, base_path): self._base_path = base_path self._base_obj = nm_dbus_path_processor.get_nm_object(base_path) def initiate(self): """ Did not put in the __init__, as did not want to get into the dynamics of "use-before-initialization" problem. """ self._base_interface = dbus.Interface(self._base_obj, self.get_interface_identifier()) """ List the exiting things. """ self.existing_things() """ Add callbacks for runtime addition and removal. """ bus.add_signal_receiver(self.thing_added_cb, signal_name=self.get_thing_added_signal_name(), dbus_interface=self.get_interface_identifier()) bus.add_signal_receiver(self.thing_removed_cb, signal_name=self.get_thing_removed_signal_name(), dbus_interface=self.get_interface_identifier()) def existing_things(self): """ Returns the existing "things" For eg., as a starting point of networkmanager, "things" would be devices. For a wireless device, "things" would be access-points. """ all_things_func = self.get_all_things_func() all_things_nm_dbus_paths = all_things_func() for nm_dbus_path in all_things_nm_dbus_paths: self.show_info('Found', nm_dbus_path) self.extra_processing(nm_dbus_path) def thing_added_cb(self, nm_dbus_path): """ callbacks such as 'DeviceAdded', 'AccessPointAdded' always pass a dbus-path to the callback method; this dbus-method is the key. from which further processing takes place. """ self.show_info('Added', nm_dbus_path) self.extra_processing(nm_dbus_path) def thing_removed_cb(self, nm_dbus_path): """ callbacks such as 'DeviceRemoved', 'AccessPointRemoved' always pass a dbus-path key. NOTE THAT NO FURTHER PROCESSING CAN BE DONE ON THIS DBUS-PATH - this is the last-rites method.' """ self.show_info('Removed', nm_dbus_path) # Note that extra processing is SIMPLY NOT POSSIBLE. def get_thing_type(self): return NotImplementedError def show_info(self, action, nm_dbus_path): print '\n' thing_type = self.get_thing_type() print action + ' ( ' + thing_type + ' ) :: ' + nm_dbus_path def extra_processing(self, nm_dbus_path): """ This is optional. A subtype may choose to add extra functionality""" pass def get_all_things_func(self): raise NotImplementedError def get_thing_added_signal_name(self): raise NotImplementedError def get_thing_removed_signal_name(self): raise NotImplementedError def get_interface_identifier(self): raise NotImplementedError class NMAccessPointsProcessor(BaseTypeProcessor): """ Processor for access-points for a (singular) device. """ def __init__(self, wireless_device_nm_path): BaseTypeProcessor.__init__(self, wireless_device_nm_path) def get_thing_type(self): return 'Access Point' def get_all_things_func(self): return self._base_interface.GetAccessPoints def get_thing_added_signal_name(self): return 'AccessPointAdded' def get_thing_removed_signal_name(self): return 'AccessPointRemoved' class NMWiredAccessPointsProcessor(NMAccessPointsProcessor): """ Processor for access-points for a (singular) wired device. """ """ THERE IS ABSOLUTELY NO CONCEPT OF SSID FOR A WIRED DEVICE. def __init__(self, wired_device_nm_path): NMAccessPointsProcessor.__init__(self, wired_device_nm_path) def get_interface_identifier(self): return NM_WIRED_DEVICE_INTERFACE """ class NMWirelessAccessPointsProcessor(NMAccessPointsProcessor): """ Processor for access-points for a (singular) wirelessdevice. """ def __init__(self, wireless_device_nm_path): NMAccessPointsProcessor.__init__(self, wireless_device_nm_path) def extra_processing(self, nm_wireless_access_point_path): print 'SSID is :: ' + self.get_ssid(nm_wireless_access_point_path) def get_ssid(self, nm_wireless_access_point_path): access_point_obj = bus.get_object(NM_BUS_NAME, nm_wireless_access_point_path) nm_wireless_access_point_props_interface = \ nm_dbus_path_processor.get_nm_props_interface(nm_wireless_access_point_path) ssid_dbus_byte_array = nm_wireless_access_point_props_interface.Get(NM_ACCESS_POINT_DBUS_INTERFACE, 'Ssid') ssid = "" for c in ssid_dbus_byte_array: ssid = ssid + chr(c) return ssid def get_interface_identifier(self): return NM_WIFI_DEVICE_INTERFACE class NMDevicesProcessor(BaseTypeProcessor): """ Processor for devices. """ def __init__(self, nm_path): BaseTypeProcessor.__init__(self, nm_path) def get_thing_type(self): return 'Device' def extra_processing(self, nm_device_path): device_type = self.get_nm_device_type(nm_device_path) print 'Device Type is :: ' + str(device_type) """ I REPEAT, THERE IS NO CONCEPT OF SSID FOR A WIRED DEVICE. if device_type == 1: print '\nWired Hardware found !!' NMWiredAccessPointsProcessor(nm_device_path).initiate() """ if device_type == 2: print '\nWireless Hardware found !!' NMWirelessAccessPointsProcessor(nm_device_path).initiate() def get_nm_device_type(self, nm_device_path): nm_interface = nm_dbus_path_processor.get_nm_props_interface(nm_device_path) return nm_interface.Get(NM_DEVICE_DBUS_INTERFACE, 'DeviceType') def get_all_things_func(self): return self._base_interface.GetDevices def get_thing_added_signal_name(self): return 'DeviceAdded' def get_thing_removed_signal_name(self): return 'DeviceRemoved' def get_interface_identifier(self): return NM_DBUS_INTERFACE try: bus = dbus.SystemBus() NMDevicesProcessor(NM_PATH).initiate() except dbus.DBusException, e: print e import gobject gobject.MainLoop().run() ============================================================================================= ============================================================================================= [ajay@ajay ~]$ python learn_networkmanager.py Found ( Device ) :: /org/freedesktop/NetworkManager/Devices/0 Device Type is :: 2 Wireless Hardware found !! Found ( Access Point ) :: /org/freedesktop/NetworkManager/AccessPoint/13 SSID is :: sr Found ( Access Point ) :: /org/freedesktop/NetworkManager/AccessPoint/11 SSID is :: RT2561_6 Found ( Access Point ) :: /org/freedesktop/NetworkManager/AccessPoint/0 SSID is :: NegiJuhi Found ( Access Point ) :: /org/freedesktop/NetworkManager/AccessPoint/2 SSID is :: Ad-hoc Network 1 Found ( Access Point ) :: /org/freedesktop/NetworkManager/AccessPoint/1 SSID is :: vanshika Found ( Device ) :: /org/freedesktop/NetworkManager/Devices/1 Device Type is :: 1 Found ( Device ) :: /org/freedesktop/NetworkManager/Devices/2 Device Type is :: 3 Added ( Access Point ) :: /org/freedesktop/NetworkManager/AccessPoint/14 SSID is :: Added ( Access Point ) :: /org/freedesktop/NetworkManager/AccessPoint/15 SSID is :: 24651045 Added ( Access Point ) :: /org/freedesktop/NetworkManager/AccessPoint/16 SSID is :: star Added ( Access Point ) :: /org/freedesktop/NetworkManager/AccessPoint/17 SSID is :: MTNL Added ( Access Point ) :: /org/freedesktop/NetworkManager/AccessPoint/18 SSID is :: Removed ( Access Point ) :: /org/freedesktop/NetworkManager/AccessPoint/2 Removed ( Access Point ) :: /org/freedesktop/NetworkManager/AccessPoint/14 Removed ( Access Point ) :: /org/freedesktop/NetworkManager/AccessPoint/12 Added ( Access Point ) :: /org/freedesktop/NetworkManager/AccessPoint/19 SSID is :: Ad-hoc Network 1 Removed ( Access Point ) :: /org/freedesktop/NetworkManager/AccessPoint/15 Added ( Access Point ) :: /org/freedesktop/NetworkManager/AccessPoint/20 SSID is :: 24651045 Added ( Access Point ) :: /org/freedesktop/NetworkManager/AccessPoint/21 SSID is :: MANUTD Added ( Access Point ) :: /org/freedesktop/NetworkManager/AccessPoint/22 SSID is :: Added ( Access Point ) :: /org/freedesktop/NetworkManager/AccessPoint/23 SSID is :: Added ( Access Point ) :: /org/freedesktop/NetworkManager/AccessPoint/24 SSID is :: Removed ( Access Point ) :: /org/freedesktop/NetworkManager/AccessPoint/20 Removed ( Access Point ) :: /org/freedesktop/NetworkManager/AccessPoint/17 Removed ( Access Point ) :: /org/freedesktop/NetworkManager/AccessPoint/11 Removed ( Access Point ) :: /org/freedesktop/NetworkManager/AccessPoint/6 Added ( Access Point ) :: /org/freedesktop/NetworkManager/AccessPoint/25 SSID is :: RT2561_6 Removed ( Access Point ) :: /org/freedesktop/NetworkManager/AccessPoint/24 Removed ( Access Point ) :: /org/freedesktop/NetworkManager/AccessPoint/23 Removed ( Access Point ) :: /org/freedesktop/NetworkManager/AccessPoint/22 Removed ( Access Point ) :: /org/freedesktop/NetworkManager/AccessPoint/16 Removed ( Access Point ) :: /org/freedesktop/NetworkManager/AccessPoint/18 Removed ( Access Point ) :: /org/freedesktop/NetworkManager/AccessPoint/13 Removed ( Access Point ) :: /org/freedesktop/NetworkManager/AccessPoint/10 Removed ( Access Point ) :: /org/freedesktop/NetworkManager/AccessPoint/9 Removed ( Access Point ) :: /org/freedesktop/NetworkManager/AccessPoint/8 Removed ( Access Point ) :: /org/freedesktop/NetworkManager/AccessPoint/7 Removed ( Access Point ) :: /org/freedesktop/NetworkManager/AccessPoint/5 Removed ( Access Point ) :: /org/freedesktop/NetworkManager/AccessPoint/4 Removed ( Access Point ) :: /org/freedesktop/NetworkManager/AccessPoint/3 Removed ( Access Point ) :: /org/freedesktop/NetworkManager/AccessPoint/1 Added ( Access Point ) :: /org/freedesktop/NetworkManager/AccessPoint/26 SSID is :: vanshika Added ( Access Point ) :: /org/freedesktop/NetworkManager/AccessPoint/27 SSID is :: Added ( Access Point ) :: /org/freedesktop/NetworkManager/AccessPoint/28 SSID is :: Added ( Access Point ) :: /org/freedesktop/NetworkManager/AccessPoint/29 SSID is :: Added ( Access Point ) :: /org/freedesktop/NetworkManager/AccessPoint/30 SSID is :: Removed ( Access Point ) :: /org/freedesktop/NetworkManager/AccessPoint/21 Added ( Access Point ) :: /org/freedesktop/NetworkManager/AccessPoint/31 SSID is :: sr Added ( Access Point ) :: /org/freedesktop/NetworkManager/AccessPoint/32 SSID is :: 24651045 Added ( Access Point ) :: /org/freedesktop/NetworkManager/AccessPoint/33 SSID is :: Added ( Access Point ) :: /org/freedesktop/NetworkManager/AccessPoint/34 SSID is :: Added ( Access Point ) :: /org/freedesktop/NetworkManager/AccessPoint/35 SSID is :: Removed ( Access Point ) :: /org/freedesktop/NetworkManager/AccessPoint/30 Added ( Access Point ) :: /org/freedesktop/NetworkManager/AccessPoint/36 SSID is :: Added ( Access Point ) :: /org/freedesktop/NetworkManager/AccessPoint/37 SSID is :: Removed ( Access Point ) :: /org/freedesktop/NetworkManager/AccessPoint/34 Removed ( Access Point ) :: /org/freedesktop/NetworkManager/AccessPoint/32 Removed ( Access Point ) :: /org/freedesktop/NetworkManager/AccessPoint/28 Removed ( Access Point ) :: /org/freedesktop/NetworkManager/AccessPoint/27 Added ( Access Point ) :: /org/freedesktop/NetworkManager/AccessPoint/38 SSID is :: star Added ( Access Point ) :: /org/freedesktop/NetworkManager/AccessPoint/39 SSID is :: Added ( Access Point ) :: /org/freedesktop/NetworkManager/AccessPoint/40 SSID is :: Added ( Access Point ) :: /org/freedesktop/NetworkManager/AccessPoint/41 SSID is :: Removed ( Access Point ) :: /org/freedesktop/NetworkManager/AccessPoint/37 Removed ( Access Point ) :: /org/freedesktop/NetworkManager/AccessPoint/36 Removed ( Access Point ) :: /org/freedesktop/NetworkManager/AccessPoint/35 Removed ( Access Point ) :: /org/freedesktop/NetworkManager/AccessPoint/33 Removed ( Access Point ) :: /org/freedesktop/NetworkManager/AccessPoint/31 Added ( Access Point ) :: /org/freedesktop/NetworkManager/AccessPoint/42 SSID is :: sr Added ( Access Point ) :: /org/freedesktop/NetworkManager/AccessPoint/43 SSID is :: Added ( Access Point ) :: /org/freedesktop/NetworkManager/AccessPoint/44 SSID is :: Added ( Access Point ) :: /org/freedesktop/NetworkManager/AccessPoint/45 SSID is :: Added ( Access Point ) :: /org/freedesktop/NetworkManager/AccessPoint/46 SSID is :: Added ( Access Point ) :: /org/freedesktop/NetworkManager/AccessPoint/47 SSID is :: Removed ( Access Point ) :: /org/freedesktop/NetworkManager/AccessPoint/40 Removed ( Access Point ) :: /org/freedesktop/NetworkManager/AccessPoint/39 Removed ( Access Point ) :: /org/freedesktop/NetworkManager/AccessPoint/29 Added ( Access Point ) :: /org/freedesktop/NetworkManager/AccessPoint/48 SSID is :: Added ( Access Point ) :: /org/freedesktop/NetworkManager/AccessPoint/49 SSID is :: Added ( Access Point ) :: /org/freedesktop/NetworkManager/AccessPoint/50 SSID is :: Removed ( Access Point ) :: /org/freedesktop/NetworkManager/AccessPoint/45 Removed ( Access Point ) :: /org/freedesktop/NetworkManager/AccessPoint/44 Removed ( Access Point ) :: /org/freedesktop/NetworkManager/AccessPoint/43 Removed ( Access Point ) :: /org/freedesktop/NetworkManager/AccessPoint/42 Added ( Access Point ) :: /org/freedesktop/NetworkManager/AccessPoint/51 SSID is :: MTNL Removed ( Access Point ) :: /org/freedesktop/NetworkManager/AccessPoint/47 Removed ( Access Point ) :: /org/freedesktop/NetworkManager/AccessPoint/38 Added ( Access Point ) :: /org/freedesktop/NetworkManager/AccessPoint/52 SSID is :: Removed ( Access Point ) :: /org/freedesktop/NetworkManager/AccessPoint/25 Added ( Access Point ) :: /org/freedesktop/NetworkManager/AccessPoint/53 SSID is :: RT2561_6 Added ( Access Point ) :: /org/freedesktop/NetworkManager/AccessPoint/54 SSID is :: MANUTD Added ( Access Point ) :: /org/freedesktop/NetworkManager/AccessPoint/55 SSID is :: Added ( Access Point ) :: /org/freedesktop/NetworkManager/AccessPoint/56 SSID is :: Added ( Access Point ) :: /org/freedesktop/NetworkManager/AccessPoint/57 SSID is :: Removed ( Device ) :: /org/freedesktop/NetworkManager/Devices/2 =================================================================================== Thanks a ton again :) :) :) Regards, Ajay <div class="gmail_quote">On Wed, Mar 7, 2012 at 4:06 AM, Sascha Silbe <<a href="mailto:silbe@activitycentral.com">silbe@activitycentral.com</a>> wrote: <blockquote class="gmail_quote" style="margin:0pt 0pt 0pt 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">Excerpts from Ajay Garg's message of 2012-03-03 04:46:33 +0100: > I have written a very basic python program, that utilizes Networkmanager > dbus-apis, to detect addition/removal of network devices. > It's working as expected, when I insert a 3G USB modem (both addition and > removal callbacks are hit as expected). > > However, when I try this with > > a. Inserting/Removing a wired network jack > b. Enable/Disable Wireless from the Dell Keyboard > c. On/Off the wireless modem-cum-router-cum-accesspoint > > neither of the callbacks is hit. Yes, that's expected. The signals you connect to are for network _hardware_ (dis)appearing. a) is just making a new (wired) network on the existing wired ethernet interface available. NM will usually connect automatically to this new network ASAP. b) depends on how its implemented in hardware. On the XO-1, it would power down the wireless network module completely, causing it to drop off from USB and thus really cause a DeviceRemoved / DeviceAdded signal. On most systems, only the radio gets disabled, so the device will stay visible. c) is just making a wireless network (un)available. Depending on settings, NM may or may not try to connect to it automatically. In any case there's no hardware that (dis)appears, just a network (Basic Service Set (BSS) in IEEE 802.11-speak). If you want to see NM connecting to networks, you can either listen to the StateChanged signal on each device (to see when/if you're connected) or monitor [1] the (global) ActiveConnections property (which gives you a list of object paths of the active connection objects [2] that you can examine further). Sascha [1] <a href="http://projects.gnome.org/NetworkManager/developers/spec-08.html#org.freedesktop.NetworkManager.PropertiesChanged" target="_blank">http://projects.gnome.org/NetworkManager/developers/spec-08.html#org.freedesktop.NetworkManager.PropertiesChanged</a> [2] <a href="http://projects.gnome.org/NetworkManager/developers/spec-08.html#org.freedesktop.NetworkManager.Connection.Active" target="_blank">http://projects.gnome.org/NetworkManager/developers/spec-08.html#org.freedesktop.NetworkManager.Connection.Active</a> -- <a href="http://sascha.silbe.org/" target="_blank">http://sascha.silbe.org/</a> <a href="http://www.infra-silbe.de/" target="_blank">http://www.infra-silbe.de/</a> </blockquote></div>