Hello Expert List!
If possible can anybody advise me on the following scenario:
My home network (4 pcs and a laptop of varying Windows / Linux versions)
currently accesses the Internet via a 3Com OfficeConnect ISDN router. The
machines are connected to a hub, which in turn uplinks to the router.
Currently the router has an internal IP address of 172.18.9.30 and the
machines have IP's in the range of 172.18.9.* - On connecting to my ISP a
dynamic IP is allocated to the external port of the router and it performs
NAT accordingly. The default gateway in each machine is set to the internal
IP of the router and everything works fine.
What I'm trying to do is put a Linux box (Mandrake 7.2) as a proxy server /
firewall in between the hub and the router to increase security and offer
proxying facilities. I'm fairly new to Linux (been playing with Mandrake
for about 6 months), but have a reasonable knowledge of networking.
So far I've fitted 2 network cards in the Linux box, eth0 is 172.18.9.100
and is connected to the router and eth1 is 172.18.9.101 and is connected to
the hub of the internal network. I've enabled routing in linuxconf, and the
default gateway is set at 172.18.9.30, at this point from this Linux box I
assumed that I would be able to a:) ping the other machines on my network
and b:) be able to ping the router / internet. But I can only ping the
router and the internet, not the internal network. I also assumed
(wrongly?) that I'd still be able to ping the router / internet from the
rest of the machines. So now I'm a little stuck - too many years of plug
and pray with Microsoft have taken their toll!
I'd appreciate any help on getting this all set up correctly, I've got a
copy of PMFirewall and Squid - although I'm open to suggestions if there's
anything better - but first things first I'd like to get the Linux box
working as a simple "middle man" between the hub and router......
Many thanks,
Martyn
