ping problem with two external interfaces

Question

I have two different IP addresses (in a block of /29), one is on port 0 and the other is on port 2 of a Ciso 888. I am doing this so I can have two different certs with two different ip addresses.

I have tried:
1) one machine, two real interfaces, two cables (eth0 and eth2)
2) one machine, one real interface eth0 and one virtual interface eth0:1, one network cable

Using number 2) I can ping the two different ip addresses, no problem. The only problem here is that iptables does not work (I cannot create rules for eth0:1 - and yes I know about the security implications).

I have a problem with number number 1) I can ping the first ip address and I get a return, but I cannot get a return when I ping the second ip address. I can see traffic coming into the second interface but it does not return. Now one of the interfaces needs the "default" route applied (is this correct??), which is eth0.

I assume this is a routing problem? What do I need to do to get this to work?

Comments

Why do you need different rules for eth0:1? Can't you specify the IP addresses?

Answer 1

Two IP addresses within the same subnet is generally something that should be avoided if at all possible.
Check the following link
http://serverfault.com/questions/336021/two-network-interfaces-and-two-ip-addresses-on-the-same-subnet-in-linuxfor