Classic networking fails when airport s/w base active


I am running OS X 10.0.4 on a G4 and a dual USB iBook. Since a week, I succeeded in allowing the iBook to use the PPP connection of the G4 via airpoirt. The only problem is that Classic networking on the G4 since refuses to work. All I get is an error message in the style "Your router is not responding on your subnet".
( and are the IP addresses of the G4 and iBook in the airpoirt network, and as the network mask is set at, the subnet "" indeed is the airport subnet.)

Note that I used the excellent gNAT utility to setup NAT and firewall stuff, which is even for a quite experienced Mac/Unix user not that easy to do.
It created a startup file in /Libraries/StartUpItems with the following content:

# NAT service startup item - enables internet connection sharing on startup
# Created by gNAT (c) 2001 Ben Lachman
. /etc/rc.common

ConsoleMessage "Starting NAT Services"
ConsoleMessage "Configuring NAT Parameters"
/usr/sbin/sysctl -w net.inet.ip.forwarding=1
/sbin/ifconfig en1 netmask
/usr/sbin/natd -f /etc/natd.conf
/sbin/ipfw -f flush
/sbin/ipfw add divert natd all from any to any via ppp0
/sbin/ipfw add pass all from any to any

My guess is that Classic networking uses a kind of dummy router ( in order to share the internet connection OSX uses. Unfortunately, in Classic there is no access to things like the TCP/IP control panel (you can look at it, but is being managed by OSX).

Any help????? Is there anybody out there that succeeded in connecting two OSX macs via airport, sharing an internet connection and accessing that connection from either Mac under OSX native or Classic? If so, what was the big trick? :confused: