Re: Gnome 3, Network-Manager & ifupdown

[Dan Williams <dcbw redhat com>]

On Fri, 2011-12-23 at 00:09 +0100, David BERCOT wrote:
> Hello,
> 
> I'm a Debian (sid) user under Gnome 3.2.
> 
> Because I have many places to configure, I use guessnet
> in /etc/network/interfaces. Then, I'd like Network-Manager not to think
> I'm not connected, so, I've added :
> [ifupdown]
> managed=true
> in /etc/NetworkManager/NetworkManager.conf
> 
> Now, I have two questions :
> 1. how can I ask Network-Manager to automatically use the connection
> choosen in /etc/network/interfaces ? I'd like not to have to click on
> the "Ifupdown (myconnection)"...
> 2. when my wired cable is not connected, how can I do a "basic"
> configuration ? Maybe it is in /etc/network/interfaces, but I've tried :
> iface eth_disconnected inet manual
> 	test missing-cable
> and it does not work...

I think the answer here is that this is attempting to encode logic into
configuration files, which doesn't usually play that well.  Yeah, it
works if you want to manually manage all this stuff, but in general you
want your network configurations separate from the logic like guessnet
that's supposed to figure out which one to use.  The 'script' parts
of /e/n/i don't get executed because there's really no interface there
or any way to move information back and forth between the script and
what's calling it.

The shorter answer is that we'd like something like this in
NetworkManager and we've had discussions about it before but haven't had
more movement on the issue.  Essentially it would be the same thing: a
know MAC address and possibly a known IP address to ping and match the
response's MAC to the known MAC.  Then NM itself would automatically do
what guessnet does.

NM's ifupdown support is simply for reading the configuration in that
file.  It doesn't (nor can it) do much of anything with the logic (ie,
scripts, tests, etc) because there's really no API there.  By which I
mean, what is the "test" directive supposed to do? Is that specific to
guessnet?  If we had native support for guessing wired connections in NM
then perhaps we could transparently read the guessnet parameters and use
them though.

So on to solutions...  there may be some way to automate this in the
mean time by using the NM D-Bus API or the dispatcher hooks, but I'm not
100% sure they'll replace the functionality that guessnet has.  In the
end I think we just need to implement it for real in NM (just like we
need to implement captive portal login and other stuff that's similar
but which guessnet doesn't do) to make this stuff work smoothly.

Dan