RE: [FW1] LAN to LAN VPN with same IP scheme

["Murphy, Paul" <Paul.Murphy@FW1-NOSPAMlloydstsb.co.uk>]

You should have a look in the archives as there was a thread about this
recently.

>From an IP perspective you can't do this.  If your machine is on 10.0.0.1/8
and the machine you want to talk to is on the other network with the address
10.0.0.2/8, then your IP stack is going to arp for the address, not route to
it.  The stack will rightly assume that it is on the same network as you.

So what you need to do is represent each of the networks to each other with
different address ranges.  

So that if you want to talk as above, you would connect to 11.0.0.2 and have
that translate to 10.0.0.2 when it arrived at the destination firewall, and
your source translate to 13.0.0.1.

Double NAT all the way.

-----Original Message-----
From: Rodney Lacroix [mailto:RLACROIX@velcro.com]
Sent: 17 October 2000 18:18
To: fw-1-mailinglist@lists.us.checkpoint.com
Subject: [FW1] LAN to LAN VPN with same IP scheme



Can anyone tell me how you would configure two LAN's to communicate via VPN
when each lan has the same network numbers?

For example, network 1 is a 10.x.x.x network, and so is network 2 -
therefore theoretically having duplicate IP addresses.  How does the client
know when to initiate a SecuRemote connection if it's destination address is
the same as an address on the local LAN?

Rodney Lacroix



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