[NetworkManager] blacklisting auto dhcp interfaces in gutsy

Matt Zimmerman mdz at ubuntu.com
Mon Sep 10 12:05:14 BST 2007

On Mon, Sep 10, 2007 at 12:38:57PM +0200, Alexander Sack wrote:
> On Mon, Sep 10, 2007 at 10:23:06AM +0100, Matt Zimmerman wrote:
> > On Mon, Sep 10, 2007 at 10:23:42AM +0200, Alexander Sack wrote:
> > > On Fri, Sep 07, 2007 at 06:25:24PM +0100, Matt Zimmerman wrote:
> > > > I'm afraid I'm not up to speed on the technical issues involved here, but
> > > > the proposed change in behaviour would be a regression for users.  If I
> > > > understand correctly, folks who installed 7.04 and are happily using
> > > > network-manager (with the default 'auto dhcp' entries in /e/n/interfaces)
> > > > would suddenly see it stop working.
> > > > 
> > > 
> > > Yes, if we don't provide an upgrade path to correct this, those
> > > users will suddenly see it stop working. However, there are also
> > > things to win: For instance you finally will be able to go to network
> > > admin in gnome, configure your connection as dhcp and just use that
> > > without network-manager getting in your way. Currently your only
> > > choice to use the auto dhcp /e/n/i feature is to purge
> > > network-manager ... which can't be the right answer imo.
> > 
> > Adding an option (even a bogus non-existent one) to the stanza in
> > /e/n/interfaces is at least marginally better than that solution.
> > 
> > The sort of folks who want network-manager "out of their way" and to modify
> > the configuration by hand should certainly be capable of either of these
> > solutions.
> I am not sure that everybody who wants a stable auto dhcp interface
> has the knowledge to figure out these workarounds (especially the
> /e/n/i hack) ... anyway, I agree that workarounds exists.
> However, these workarounds are only needed because we do _try_ to
> manage those auto dhcp interfaces through network manager (note: i say
> "try" because network manager will not be able to handle those
> gracefully, no matter how hard we try).

Agreed.  I believe this was originally Scott's decision, in trying to find a
compromise between network-manager and ifupdown.  If you haven't already,
check with him about whether the reasons for it may still apply (and need to
be addressed some other way).

> Once we stop doing this, no workarounds (e.g. for the cases below)
> would be needed anymore; isn't this what we want in the end?
> OK, here some cases we might want to consider when discussing this:
>  1. novice users - just wants to use network manager to manage one
>  connection at a time. Even though novice users probably don't
>  have any opinion ;), they probably don't want all their interfaces to
>  be upped during startup (through /e/n/i), just to get them downed
>  again as soon as NetworkManager starts up.

Agreed.  The novice experience is, and should remain, "Network Manager just
happens".  This includes folks upgrading from previous releases.

Network interfaces should be brought up as early as possible, modulo
authentication etc.

>  2. advance users that only want to use /e/n/i: currently they have to
>  purge network-manager or have to use a workaround in /e/n/i (which is
>  not available through gnome network-admin).

If what they want is specifically to avoid network-manager, uninstalling it
seems like a reasonable action to expect (this also removes the applet
automatically, which otherwise simply becomes non-functional).

To restate this in the form of use cases:

Sally installs an Ubuntu desktop, but finds Network Manager doesn't do
everything she wants yet, and therefore uninstalls it.  Everything then
works as it does in Debian, and interfaces are managed in

Robert installs an Ubuntu desktop, but finds that Network Manager doesn't do
everything he wants yet.  He adds some entries to /etc/network/interfaces,
and Network Manager ignores those interfaces.

Jonathan installs an Ubuntu server.  Network Manager doesn't get installed,
and everything works as it always has in Ubuntu and in Debian.

>  3. advance users that want a mix of both (wired through /e/n/i auto
>  dhcp, but wireless still managed through NM); they don't have the
>  option to purge network manager and thus only have the /e/n/i
>  workaround as a fallback.

Again, in use case language:

Alison installs an Ubuntu laptop, but she really wants her primary ethernet
interface to be nailed up and not subject to Network Manager's whims.  She
adds the interface to /etc/network/interfaces, and Network Manager then
ignores that interface, still allowing her to use it for wireless
connections when traveling.

 - mdz

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