Re: Idea - Detecting IP conflicts in NM

[Dan Williams <dcbw redhat com>]

On Thu, 2011-04-28 at 22:44 +0300, Ozan Çağlayan wrote:
> On 27.04.2011 22:29, Dan Williams wrote:
> 
> >> follow-up for gratuitous arp replies:
> >>  http://forum.nginx.org/read.php?31,75057
> > 
> > This would be cool; we could do it after getting the IP address if we
> > wanted to in nm-device.c or elsewhere before we've even assigned the IP
> > address to the card.  Alternatively, if we wanted to keep lower latency
> > we could do it after we've assigned the address and said we're connected
> > like other OSs do and warn the user or something.  Is this a patch you'd
> > be willing to work on?  If so that would be great!
> 
> Not yet. I've played with the duplicate address detection (DAD) mode of
> the arping tool but it seems that on systems that I've tried, the
> endpoints don't reply to gratuitous ARPs. There's probably a /proc/*
> tunable that's disabled by default which ignores those requests.
> 
> Applets can even offer getting an IP from the DHCP server in case of
> conflicting IP situations or alternatively, NM can assign the IP but
> applets can warn the user about the situation (or even a limited or
> problematic connection icon can be overlayed on the applet's icon in the
> tray)
> 
> Seen that it's acceptable from upstream, I'll try to implement this
> step-by-step.

Yeah, we can at the very least implement the DAD stuff and check for a
duplicate IP; NM 0.9  makes this easier because there's the IP_CHECK
activation stage in which this stuff should happen.

Dan