Configuring NM as a router

[Xavier Bestel <xavier bestel free fr>]

Hi,

I have a machine with 3 interfaces (well, technically there are more of
them but let's ignore that):
- one "upstream" eth0 interface with a public IPv4 address
- one "local" eth0 interface, 192.168.1.x
- one "local" wlan0 interface, 192.168.2.x

I want my machine to act a a router for the "local" network, i.e.:
- NAT-ing the public IPv4 upstream address to local nets
- have every machines in the local nets to be accessible to each other
- have every machines names visible to each other

In fact I'd like to configure NM for my machine to act like a regular
OpenWRT router. However I'm stuck with a few problems:
- NM creates many dnsmasq instances which do not communicate with each
other, so machines from 192.168.1.x can't see names of 192.168.2.x
- NM fails to setup routes correctly, see https://bugzilla.gnome.org/sh
ow_bug.cgi?id=782348
- I can't find a way to have a "global" dnsmasq (manually configured)
running and still have NM setup the eth1 and wlan0 interfaces correctly
(especially the access point)

Is my need so alien to NM ? Or is there some doc somewhere on how to do
that ?

Regards,
        Xav