I have the following hypothetical scenario -
I have an existing wired LAN, which may or may not already have a wireless network (and which should not be used/interfered with). I also have a few linux systems I would like to plug in to this wired LAN, and use them as wireless access points. Clients connecting to these APs will have internet access, but not LAN access (which should be no problem through iptables, I believe). The linux systems may or may not be within range of each other.

Here is my dilemma - I would like to have the systems automatically detect upon boot if another nearby system is already up and running an access point. If it is, the newly booted system should join it and extend the network - otherwise, they should become the first to host the network. It should also be able to respond to events like the original host shutting down, etc.

Is this even possible? I have some networking and iptables experience, but nothing on this scale. I would greatly appreciate if somebody experienced can help me out on this issue.