Let's say I want to create an internal network with 4 subnets. There is no central router or switch. I have a "management subnet" available to link the gateways on all four subnets (192.168.0.0/24). The general diagram would look like this:
10.0.1.0/24 <-> 10.0.2.0/24 <-> 10.0.3.0/24 <-> 10.0.4.0/24
In words, I configure a single linux box on each subnet with 2 interfaces, a 10.0.x.1 and 192.168.0.x. These function as the gateway devices for each subnet. There will be multiple hosts for each 10.x/24 subnet. Other hosts will only have 1 interface available as a 10.0.x.x.
I want each host to be able to ping each other host on any other subnet. My question is first: is this possible. And second, if so, I need some help configuring iptables and/or routes. I've been experimenting with this, but can only come up with a solution that allow for pings in one direction (icmp packets are only an example, I'd ultimately like full network capabilities between hosts e.g. ssh, telnet, ftp, etc).