On 5/8/07, David Lang <david.lang@xxxxxxxxxxxxxxxxxx> wrote:
On Tue, 8 May 2007, semi linux wrote: > I've got an odd problem where I've got two NICs on the same network > and I want all traffic to one IP to go out one interface and all other > traffic to use the second interface. I'm going to try an simplify my > actual setup, because a lot of it makes no difference to this post... > > I know this has to be a iptables sort of setup since the routing table > can only make a difference on different networks and not based on > looking for a specific IP address. > > The question is: > > eth0 IP: 10.1.1.1 > eth1 IP: 10.1.1.2 > > target: 10.1.1.3 > > (these IPs are just examples, there are no hard-fast rules surrounding > the other possibilities) > > How do I make sure this goes out eth1 instead of eth0? Do I use the > mangle rule with the physdev module? > > I feel like I'm overlooking something or forgetting my basic network > ideas here... you haven't quite given enough info here if you have target2 10.1.1.4 and you want all traffic to target to go out eth0 and all traffic to target2 to go out eth1 then you would want to start out with defining host routes (the routing table _can_ look at specific hosts, not just networks) in addition, I believe that you will need to play around with arp filtering to make sure that each NIC only responds to arp requests for it's IP addresses. if you really only have one remote IP address and two local addresses and you want all communications between the target and 10.1.1.1 to use eth0 while all communications between the target and 10.1.1.2 to use eth1 things get more complicated you would need to look into packet/connection tagging and iptables routeing decisions. rather then try and go into that right now why don't you try to be a little clearer about exactly what you are trying to do. David Lang
Ok... you asked for the whole thing, here it is (forget my previous example): eth0 - 10.1.1.1 eth1 - N/A eth2 - N/A br0 (eth1, eth2) - 10.1.1.2 target - 10.1.1.3 The bridge (br0) is setup using brctl and seems to work w/o problem... The eth1 and eth2 IP addresses really don't matter since they are both referenced via the bridge and are set to something invalid. 10.1.1.3 is connected via cross-over cable to eth2 port. br0 and eth0 are connected to my network on the same subnet. What I'd like: - all packets (from the network or local) where destination=10.1.1.3 to be routed to eth2. - otherwise, all traffic from the network to use eth0 for I/O. Basically, I want to specify that ONLY traffic for 10.1.1.3 is to use eth2.
