Re: force nm to use a connection

[Dan Williams <dcbw redhat com>]

On Wed, 2009-03-11 at 11:52 +0100, Alexander Sack wrote:
> On Wed, Mar 11, 2009 at 06:40:31AM -0400, Dan Williams wrote:
> > On Wed, 2009-03-11 at 11:34 +0100, Alexander Sack wrote:
> > > On Wed, Mar 11, 2009 at 12:10:40AM +0100, Jérôme PRIOR wrote:
> > > > hello,
> > > > 
> > > > I'm looking for info to force nm to use a connection instead of "Auto
> > > > eth0". I explain :
> > > > 
> > > >   at home I need a static IP, with special DNS, ... So, I created a
> > > >   connection called `home` with those parameters. Works fine when I
> > > >   activated it manually.
> > > > 
> > > >   When I'm outside, I need `auto eth0`.
> > > > 
> > > > How can I tell nm "when I'm at home, connect me via `home`, even if
> > > > connect me via `auto eth0` ?
> > > > 
> > > > I try to pla with "automatic connection" but of course, if I put `home`
> > > > as auto, and `auto eth0` as no-auto, when I'm outside, `home` is up.
> > > > And inversement.
> > > > 
> > > 
> > > NetworkManager currently has no "smart" tie-break logic to decide
> > > which auto connection to use. Not sure, but maybe it prefers the last
> > > one that was active.
> > 
> > Yes, it uses the last connected Ethernet connection.  For wifi, it uses
> > the last connected AP that's currently visible.
> > 
> > > Not sure if we could come up with something smarter for wired. Any ideas?
> > 
> > Not for plain wired, unless you want to try ARP sniffing or ARP-ing a
> > known IP address to match a known MAC address or something.  Not that
> > that is in any way secure, and it would also increase connection
> > latency.  But maybe that's a worthwhile tradeoff to get the right wired
> > connection; most people will only have one or two, so a few seconds to
> > sniff which connection to use (if its been configured that way) might be
> > worth it.
> > 
> 
> I think it would be worth it and would be in line with NM's idea of
> being as smart as possible :). I am not sure about the security
> implications, but how does current autoconnect strategy not come with
> the same risks?
> 
> Also related, how about probing for pppoe concentrators to add more
> automagic on that front?

Can you point me to some info on how that can be done?

Tambet also said we can autodetect 802.1x-enabled switches as well.

Dan