Re: Preventing IP conflict

On Fri, Dec 21, 2007 at 02:44:03AM +0000, T o n g wrote:
> Ops, yeah, I meant DHCP. I'm using DHCP instead of static ip. both under
> windows and under linux.
>
> > As it was said by Douglas, if you have a problem under windows, it is
> > not a linux problem but a network problem.
>
> yes, it is definitely because of the malfunctioning of our organization's
> DHCP server -- giving the same IP to more than one computers. Or, maybe
> something else?

Other possibilities include the other computer being set (i.e., illegally) to a static ip; your computer timing out in its dhcp request and defaulting to a previously-held ip; somebody spoofing their interface's mac address and so causing the dhcp server to think they're the same; ...

In any case, this is a basic problem that needs to be fixed, and hopefully your tech group is up to the task. Politically it sounds like it might be simpler to approach them with the Windows version of your problem, assuming it exists.  

> > Second check, as Douglas said, that the mac address are the same under
> > the 2 OS . . .
>
> I haven't got around to reboot into window$ and check yet. But I believe
> that they are the same. I'll post immediately if otherwise.

Unless they're different interfaces, and unless there's a setting somewhere changing the mac address, they ought to be the same.
>
> > When your problem come back, use the command i gave you (under windows
> > or under Linux according the case) and report immediatly the information
> > to the network administrator. At this time, it can search on the network
> > where the ip address is used from another machine.
>
> Can I do that myself from my Linux box?

I don't know what command was pointed out, but you can get all the settings for your machine, and possibly very little about others on the network. Most networks use switches instead of hubs, and the effect is to isolate you from (most) other traffic not directed at your machine. You may still be able to see broadcast packets from others, and then might be able to see the offending ip and its mac address, e.g., using ... (can't think of the name...) ... a utility to inspect packets on your box.

Ken

-- 
Ken Irving, fnkci+debianuser@uaf.edu


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