[Babel-users] How should an AHCP server configure it's ip address?

[Kenneth Finnegan]

Greetings,

I'm working on building a mesh between a number of Ubuntu 10.04 boxes.
 I've managed to get babeld, ahcpd, and iptables all working together
nicely, so I've got routes between all of them, internet gateways, the
whole bit.

The problem is that I don't quite understand how the node running AHCP
-C "mode server" should set up it's wlan0 (mesh) IP address...  Leave
it unconfigured, and none of the other nodes have a gateway IP out of
the mesh.  Configure nodeA:wlan0 as static 10.99.1.1/16 and ahcpd
merrily issues a lease to the first ahcp client for... 10.99.1.1.  At
this point I have it working by configuring the ahcpd server node as
10.99.1.254/16 while distributing 10.99.1.0/24, but that seems like a
bad solution since it will still willingly issue that (higher) IP
address to an ahcp client (eventually).

The question comes down to this: how do I keep an ahcp server from
issuing a lease for it's own IP address?

I can think of a number of solutions, but looking through the code I
didn't pick up the scent of any of them.  I can't even figure out how
CeroWRT got it to behave correctly (Server is 172.30.42.224 with the
prefix 172.30.42.224/27 and the first ahcp client correctly receives
172.30.42.225).

Kenneth Finnegan
blog.thelifeofkenneth.com