OT: Help with Routing please..

[Sanjay Arora]

Hi all

This question is not Fedora related, but could not find how to do this.
Being a newbie, decided to ask the masters ;-)

Network 1.

Ipcop firewall gateway..

Public address: 202.x.x.139 Netmask 255.255.255.248 given by ISP
DMZ: 192.168.100.1
Lan: 192.168.200.1

Gateway to Internet through 202.x.x.137 provided by ISP.

Network 2 (ISP Network...mostly hubs/repeaters & some switches)

NAT Gateway to internet through ISP provided by ISP through 172.16.0.1
My FC1 machine address: 172.16.0.133 Netmask 255.255.255.0, though I
have not set it, as the ISP does not allow me to go on the net through
this GW...only has given me an IP address to use on the local
net...basically to test my machine his network i.e. from outside my
network.

Other friends on ISP LAN connected through the ISP: 172.16.0.x

Now, the problem is that my FC1 machine though physically connected to
my public IP (three connections to the hub...my ISP, my Ipcop machine
and my FC1 machine), does not talk to my public IP.

Ping says destination unreachable...I used ethereal to check the
problem...my public IP firewall machine (202.x.x.139) is not responding
to FC1 (172.16.0.133) ARP requests. I have set route in both machines
by:

On 172.16.0.133
route add -host 202.x.x.139 dev eth2

On 202.x.x.139
route add -host 172.16.0.133 dev eth2

I think that the problem lies with different broadcast addresses, so the
202.x.x.139 machine is not getting the ARP request.

My firewall does not block ICMP requests.

Second problems is with my friends having 172.16.0.0 address with my ISP
and having a GW address of 172.16.0.1 (which my FC1 machine does not
have). They cant connect to my machine despite being on the same segment
of my ISP Lan, without going through the internet. As their Internet
bandwidth is capped...they cant transfer files with me. How to get their
machines to talk with mine, without going to the ISP Gateway...some are
Win machines & some Linux.

Hope someone will help me...wont say can help me because I know
otherwise ;-) Also, please provide pointers to some resources to this
type of (not normal) TCP/IP routing...so I can learn and maybe someday
be able to help some newbie like myself. Strangely...Google was not my
friend this time ;-(

My thanks for reading ALL the above.

With best regards.
Sanjay.