I have a rather bizarre network setup:
I have two separate subnets, a 192.168.1.0 and 10.1.1.0 which both coexist on the same physical network. Splitting the networks is impossible for a multitude of reasons.
The 192.168.1.0 subnet has a debian box running netfilter which nats it to a real IP address on the internet (via a cable modem).
The 10.1.1.0 subnet has a proprietary router which does some 1:1 nat for low addresses, and many:1 nat for high addresses. Traffic on this subnet reaches the internet through a T1.
The problem is that a large percentage of the traffic outbound on the 192.168.1.0 subnet is destined to the external ips of a hosts (say A) on the 10.1.1.0 subnet, thus wasting bandwidth in both directions. I can't simply add an alias to host A, as it is a complicated server, and wouldn't take well to that sort of thing.
The question is how do I make A directly reachable from the 192.168.1.0 subnet? I don't want to do any nat with netfilter, because slots in the conntrack table are already at a premium. Ideally, I would like to add some rule or route which would tell hosts that A is directly reachable (currently, if you try to ping 10.1.1.6 (A's address) from the 192.168.1.0 subnet, you get a no route to host error).
Any thoughts would be much appreciated.
-- Brian Howard
