Re: Understanding How Networking Manager Manages Wi-Fi

[Dan Williams <dcbw redhat com>]

On Tue, 2015-09-22 at 19:54 +0530, Ramprasad Vempati wrote:
> Hi,
>
> I'm interested to understand the flow, in terms of how Network-Manager
> controls Wi-Fi. As far as I know Network Manager talks to
> wpa_supplicant.

Yes, through the D-Bus IPC protocol, which many services on Linux use.

> But I'm interested in more details. Like how Network-manager starts
> wpa_supplicant?

Through D-Bus service activation.  Even if the supplicant is not yet
started, NM asks the supplicant a question, and the D-Bus daemon will
hold the request, start the supplicant, and pass the request along when
it's ready.

> And another case I would like to understand is, if I kill
> wpa_supplicant that's started by Network-Manager and also remove
> wpa_supplicant from /sbin, but run wpa_supplicant from another folder,
> does Network-manager finds him & tries to control?

Yes, as long as you've built the supplicant with the D-Bus control
interface enabled (CONFIG_CTRL_IFACE_DBUS_NEW), and you've started the
supplicant with the "-u" option to enable it at runtime.

Dan

> I tried google to get this information. But I couldn't find any useful
> information.
>
> Can one of you help?
>
> Thanks,
> Ram
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