ip_forwarding / gateway


I am building a network of Linux boxes running a small self-made Linux. One
of these boxes is setup as a dial-in server for the network. I have the
dial-in part up and running, but have difficulties configuring the network
such that I can reach the Linux boxes from out of the network.

This is my setup: <---ppp---> <---ip_forwarding on the dial-in
server---> <--- eth ---> <--- eth --->

My dial-in server has ip address on the ppp connection and on the eth connection. 192.168.5.x is the Linux network.
Ip_forwarding is turned on the dial-in server.

Using the pc with IP address, I am able to ping the Linux
dial-in server on both its IP addresses ( and
However, I cannot reach the Linux boxes with IP addresses and
up. When I ping these boxes, I can see the lights of the Ethernet cards
flicker, but the ping requests time out.

Am I overlooking something? Any help is greatly appreciated.