From mboxrd@z Thu Jan 1 00:00:00 1970 From: Grant Taylor Subject: Re: Awkward scenario: 3 interfaces and 3 devices with same ip/subnet. Date: Tue, 31 Aug 2010 09:30:13 -0500 Message-ID: <4C7D11F5.1010105@riverviewtech.net> References: Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: Sender: netfilter-owner@vger.kernel.org List-ID: Content-Type: text/plain; charset="us-ascii"; format="flowed" To: Mail List - Netfilter On 08/31/10 06:34, Giacomo Bernardi wrote: > want to solve a very awkward scenario? > > There's a linux box with three interfaces (eth0, eth1, eth2) each > directly connected to an embedded device that has configuration: > - IP: 10.0.0.1 > - Mask: 255.255.255.0 > (in other words: all three devices answer to 10.0.0.1/24 and their > configuration can't be changed) > > I need to send and receive snmp packets to an arbitrary given device > among these three ...how? I don't know if it would work for you or not, but you could try an old / odd / if not dirty trick. Try adding static ARP entries to each device's MAC address using different (bogus) IPs. Then try communicating with the bogus IPs. You might get lucky and be able to communicate. It really depends on what is included in the higher layer protocol. (I've not dealt with enough SNMP to know if this is possible.) The main thing that the differing IPs are use for is to translate the layer 3 IP address to the layer 2 MAC address. So, if you can side step that problem, you may be golden. Yes, this is a dirty trick / hack, but sometimes that's what you have got to do. Grant. . . .