[plug] ip address and interface question

[meyerri]

---- Original Message ----
From: zombie at penguincare.com.au
To: plug at plug.org.au
Subject: Re: [plug] ip address and interface question
Date: Fri, 23 Jun 2006 09:52:53 +0800 (WST)

>Hi Jason, welcome to the list!
>
>On Fri, 23 Jun 2006, quoth Jason:
>
>> This is an annoyance that I've had since first installing linux on
>my laptop a couple of years ago and finally thought I'd try to find
>out how to fix
>> it :)
>
>That's because it's a feature, not a bug! ;)
>
>Well, not really, but it's been a known "feature" for as long as I
>can
>remember.  I remember seeing a question on linux-kernel about it
>years
>ago, and the reasoning behind it, is that the code that checks
>incoming
>packets to see if "it's one of our IP addresses" does not check which
>interface the packet was received on, and if you only do "ifconfig
>down"
>on an interface it does not remove the associated IP address from the
>"this is one of ours" list.

Might be interesting to do a "traceroute" or whatever the command is
these days (I know it's changed under SUSE) to see which interfaces
it goes through when the interface is up and again when down.
>
>> I have two interfaces, eth0 (wired) and eth1 (wireless ipw2200
>> drivers).  eth0 is configured with the ip address of 192.168.0.4
>and
>> eth1 192.168.0.5.
>
>You really should not have two interfaces in the same machine on the
>same
>physical network - although I guess you are bringing one interface up
>as
>you bring the other interface down so you can switch between wired &
>wireless.
>
>The way I do that is to ensure I do "ifconfig ath0 0.0.0.0 down" to
>both
>remove the IP address and bring down the interface, before I bring
>the
>other interface up.
>
>I'm toying with the idea of adding both my interfaces (ath0 and eth0)
>to a
>bridge (br0) and enabling spanning tree on my switch, which means I
>should
>be able to use the same IP address no matter which interface is
>connected.
>
>The problem is, that will only work on stp-capable networks,
>otherwise
>it will lead to nastyness (broadcast storms etc)
>
>Kind Regards,
>
> - Matt Kemner
>  Penguin Care		Tel: Perth 08 9322 3444	Brisbane 07 3337 9988
>  Mob: 04 1175 6910	Fax: Perth 08 9221 3444	Brisbane 07 3337 9977
>
>__
Cheers
RM