Re: force nm to use a connection

[Dan Williams <dcbw redhat com>]

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.

Dan