MAC and gateways

Hi,

I have a problem regarding preservation of MAC addresses in packets
when they cross gateways.
My question is basically if it is possible to preserve the MAC address
somehow as the packet cross the gateway.
F.ex. I have the following setup:

internet
|
ip public
Linux Server
ip 10.0.0.1
|
ip 10.0.0.2
Router A (linux based)
ip 10.0.1.1
|
10.0.1.2
Router B (linux based)
10.0.2.1
|
10.0.2.2
Client (linux based)

So if the Client sends a packet to the Server, I notice that the MAC
address of the packet as it is reaching the Server is no longer the
MAC of the Client, but equals the MAC of Router A ip 10.0.0.2

I am designing a special system, where I need to authenticate the
Client based on the MAC address and the IP of the Client (so only to
let the packet thru at the server if MAC and IP matches an entry in a
table). But if the MAC address changes then this is a problem
obviously.
So is it inherent in the protocols that the MAC changes over a
gateway, or can I change the routing somehow maybe? or can I do some
magic with the ARP tables? I should mention I have full control of all
the servers and routers and clients in this setup so a hack can also
work :-) just not really sure how to attack this problem. If it helps,
the Routers and the Clients are running RouterOS (Mikrotik), the
Server is running RH 9
Any help/ideas would be appreciated. Thanks.

Regards,
Tobias

.

Relevant Pages

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