Configuring network interface via liboobs when NetworkManager is running.

[Forest Bond]

Hi,

I'm just trying to get my head around how the network device is managed between
GST, liboobs, NetworkManager, and dhcdbd.  I'm currently working with Ubuntu
8.04, so the software versions I'm dealing with are a little bit old at this
point.

I've been looking at the source for each of these components.  It looks like NM
handles the device for DHCP configurations only.  Otherwise, GST configures the
device via liboobs and then does a sleep/wake cycle with NM so that it sees that
things have changed.

However, I can't see how this approach wouldn't be vulnerable to race
conditions.  If NM is currently managing the interface, and I switch it to a
static config, it seems like dhclient might change the config after the static
config is applied but before NM is cycled (which I assume would cause dhclient
to be killed via dhcdbd).

Is this as racy as it seems it is?

Thanks,
Forest
--
Forest Bond
http://www.alittletooquiet.net
http://www.pytagsfs.org


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[Milan Bouchet-Valat]

Hi!

IIRC, NetworkManager only handles connexions marked as auto (or not
listed at all, should check that somewhere) in /etc/network/interfaces.
In network-amin (gst tool started from System->Administration->Network),
you can see that those connexions are in "Itinerant mode", which merely
means that NetworkManager takes care of them, and that other tools (the
gst, but also Debian-specific tools like ifup). If you want to configure
an interface (with static IP or even with DHCP) from network-admin, or
use it from ifup/ifdown tools, you'll stop NetworkManager from using it.
Just check that by playing with the check box and the nm-applet list of
devices.

So there's no race condition at all, and hopefully the coexistence is
very limited. But why are you interested in this? I wouldn't advise you
to work with network-admin to manage your connexions at this point,
since in more recent versions NetworkManager has much improved. Now,
connexions are no longer handled by network-admin by default, and I
don't plan fixing bugs in that tool any more.


Cheers


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[Forest Bond]

Hi,

On Tue, Sep 01, 2009 at 12:28:18AM +0200, Milan Bouchet-Valat wrote:

> IIRC, NetworkManager only handles connexions marked as auto (or not
> listed at all, should check that somewhere) in /etc/network/interfaces.
> In network-amin (gst tool started from System->Administration->Network),
> you can see that those connexions are in "Itinerant mode", which merely
> means that NetworkManager takes care of them, and that other tools (the
> gst, but also Debian-specific tools like ifup). If you want to configure
> an interface (with static IP or even with DHCP) from network-admin, or
> use it from ifup/ifdown tools, you'll stop NetworkManager from using it.
> Just check that by playing with the check box and the nm-applet list of
> devices.

Well, it looks like I was barking up the wrong tree, anyway.
gnome-network-admin is not used in 8.04 by default.  It looks like I should be
looking at network-manager exclusively.

Sorry for the noise.

-Forest
--
Forest Bond
http://www.alittletooquiet.net
http://www.pytagsfs.org


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[Forest Bond]

Hi,

On Mon, Aug 31, 2009 at 09:00:51PM -0400, Forest Bond wrote:

> On Tue, Sep 01, 2009 at 12:28:18AM +0200, Milan Bouchet-Valat wrote:
> > IIRC, NetworkManager only handles connexions marked as auto (or not
> > listed at all, should check that somewhere) in /etc/network/interfaces.
> > In network-amin (gst tool started from System->Administration->Network),
> > you can see that those connexions are in "Itinerant mode", which merely
> > means that NetworkManager takes care of them, and that other tools (the
> > gst, but also Debian-specific tools like ifup). If you want to configure
> > an interface (with static IP or even with DHCP) from network-admin, or
> > use it from ifup/ifdown tools, you'll stop NetworkManager from using it.
> > Just check that by playing with the check box and the nm-applet list of
> > devices.
>
> Well, it looks like I was barking up the wrong tree, anyway.
> gnome-network-admin is not used in 8.04 by default.  It looks like I should be
> looking at network-manager exclusively.

Okay, correction, 8.04 *does* use gnome-network-admin, but NM is patched to
detect updates to /etc/network/interfaces while it is running.  I'm getting how
the pieces fit together now.

-Forest
--
Forest Bond
http://www.alittletooquiet.net
http://www.pytagsfs.org


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