[NetworkManager] blacklisting auto dhcp interfaces in gutsy

[Alexander Sack]

Hi,

Background:

As you might know, we made auto dhcp configured interfaces explicitly
managed by network manager in feisty (and edgy?); unfortunately
this leads to bugs because the concepts of /etc/network/interfaces
and network-manager do not go together well. For instance
network-manager can only deal with _one_ active connection at the same
time, while /etc/network/interfaces can.

The feisty answer to this problem was to ifdown all auto dhcp
interfaces during startup. However, this caused nasty bugs and was
in general perceived as a bad thing to do, so we disabled that feature
in early gutsy alpha releases. However, this is not bug free as well
and leads to confusion and non-deterministic behaviour - again
... primarly because nm is just not prepared to deal with two
managed connections being active at the same time.

In short: network manager and /etc/network/interfaces concepts do not
go together well and we should resolve this for gutsy.


Proposal:
My suggestion (and probably the right long-term approach as well) is
to finally stop mixing those concepts by taking the following steps:

  1. stop to manage (blacklist) /etc/network/interfaces configured auto
     dhcp interfaces through network-manager.
  2. adapt the (desktop) installer to not install any auto dhcp
     interfaces in /etc/network/interfaces for a default ubuntu desktop
     install.
( 3. maybe improve network-admin to make it more obvious that
     configuring a device as "enable roaming mode" implies that the
     device _will_ be handled by network-manager.)

If you have any objections, please speak up now! Otherwise I will
blacklist auto dhcp interfaces in next network-manager upload.

Comments?

 - Alexander