Thanks for your help. I greatly appreciate it.
I am understanding you to say that your two local boxes can ping each other, and that your gateway box can connect to your ISP and ping the world, but your non-gateway box can't ping the outside world (via your gateway box). If this is correct, then your gateway box does not appear to be forwarding requests from/to your non-gateway box.
Your description above of what I was trying to explain is accurate. The process I followed to set up forwarding of requests was:
and changed the following line:
net.ipv4.ip_forward = 0
net.ipv4.ip_forward = 1
But I don't know how to test if IP forwarding is in fact active, (as opposed to just changing the config file and restarting network services)
How do you do this?
The reason I started Samba at all was that coming from a windows environment I was expecting to "see" the other computer somewhere when they were connected. Of course Linux doesn't seem to do this, until I started Samba, which at least showed me an icon of the gateway machine and vice versa confirming that they could speak to each other beyond simply pinging.
When I come to actually wanting to share drives printers etc on this little home network is it more secure to use a non internet gateway box as the nfs or samba server?