VPN - supporting multiple private NAT clients

From: Venger (venger_at_augustmail.com)
Date: 10/31/03 

Date: Thu, 30 Oct 2003 22:49:25 -0600

Gentlemen -

Have a client with a pair of offices linked with Sonicwall VPN between
them - 192.168.1.X and 2.X. Works famously, better than I ever expected it
to.

We wish to connect a laptop to one of the office firewalls across the
internet via VPN. This brought about a conflagration of conflicting thoughts
about what can, and cannot, be done.

If said laptop is behind a NAT router with a 192.168.1.X address, it cannot
create a VPN to the first Sonicwall - the destination route and local route
are the same. If we were to connect to the second firewall, it would appear
that since that firewall is already attached via a site to site VPN, it
would have a conflict between two VPN connections, with overlapping address
space.

Which then begs the question... how can you support dozens of clients who
could quite possibly each have the same private NAT address, say
192.168.1.100, much less similar address space?

NAT Traversal?

Any information is definitely appreciated. Our Sonicwalls talk to each other
fine, but are barfing on connecting the laptop. I assume that NAT traversal
is an issue here, the firmware is 5.1.7.0 and they do not currently support
NAT traversal on that firmware release...

Thanks,

Venger

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