You cannot build a VPN link from internal LAN IP to internal LAN IP on
ASAs.  The tunnel is setup to communicate via the outside WAN IP
address. From there, an encryption domain access list is configured to
say which networks are allowed to communicate through the tunnel.  You
then setup an access list for NAT exemption that is identical to the
encryption domain so the ASA does not try to NAT to that network and
send it out to the internet so it knows to go through the tunnel.  The
ASAs routing table is very simple.  You can only have one default route
(0.0.0.0 with a mask of 0.0.0.0) so with that route being used to
communicate with the ISP you cannot also use that route to send traffic
across the tunnel to go out the internet. 

As far as I know from what I've seen and researched what you are
describing is not possible, with an ASA at least.  

-----Original Message-----
From: Ben Scott [mailto:[email protected]] 
Sent: Thursday, May 21, 2009 1:09 PM
To: NT System Admin Issues
Subject: Re: Cheap/Free Simple Web Proxy Server?

On Thu, May 21, 2009 at 1:45 PM, N Parr <[email protected]>
wrote:
> So the remote gateway of the ASA has to be the ISP's gateway in order 
> to find the main office.

  The ASA itself will need to have its default route by the ISP, yes.
But not the VPN tunnel.  I've never used an ASA, but I assume you can
configure the VPN such that it provides a point-to-point link between
the ASA's LAN interface at the remote site, and whatever you have at HQ.
Configure the firewall or routing tables or whatever so that the LAN
interface doesn't forward traffic between the LAN and the public
interface.  Just give it routes to the local site networks, and a
default route to gateway to HQ.  Then configure everything on the LAN to
use the ASA as the default gateway.  Now all traffic from the LAN to
anywhere goes to the ASA, which forwards it through the VPN to HQ.

-- Ben

~ Finally, powerful endpoint security that ISN'T a resource hog! ~ ~
<http://www.sunbeltsoftware.com/Business/VIPRE-Enterprise/>  ~

~ Finally, powerful endpoint security that ISN'T a resource hog! ~
~ <http://www.sunbeltsoftware.com/Business/VIPRE-Enterprise/>  ~

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