Firewall Wizards mailing list archives

RE: An interesting VPN problem


From: "Ben Nagy" <ben () iagu net>
Date: Fri, 29 Aug 2003 10:37:04 +0200

Why can't you just tell L-PIX to route to 0.0.0.0 via 192.168.20.1 on the
inside interface? If all it does is tunnel it doesn't need any other default
gateway does it? It has statics for R-Net, and you can add a static on the
out interface for the real IP of R-PIX.

I assume that this is a stupid question, but it's early here.

In any case, don't source route. At the very worst, put a cheap router
inside L-PIX and L-FW and you will easily be able to solve your problems.

ben 

-----Original Message-----
From: firewall-wizards-admin () honor icsalabs com 
[mailto:firewall-wizards-admin () honor icsalabs com] On Behalf 
Of Jonas Anden
Sent: Thursday, August 28, 2003 10:28 AM
To: firewall-wizards () honor icsalabs com

Hi all you Wizes out there. I've got a bit of a problem that 
I think you
might help me solve...

I've got two Cisco PIX 501 with the latest software (6.3.1). We're
trying to use them to set up a remote site with *all* client 
traffic on
the remote network being redirected through the site-to-site tunnel
(including the traffic that should ultimately end up on the Internet).
Traffic from the remote network not targeted for the local network
should be routed through a firewall reachable from the local network.

My network looks like this:


[L-NET]<-+--->[FW]<---+->[B-GW]<-->[INET]<-->[R-PIX]<-->[R-NET]
         |            |
         +-->[L-PIX]<-+


L-NET - The network at the central site
        Net=192.168.20.0/24

FW    - Firewall protecting the entire network and
        providing user authentication for Internet access.
        Inside IP=192.168.20.1
        Outside IP=10.0.0.2

L-PIX - Local tunnel endpoint at the central site.
        Connected to both the internal network at
        the central site and the Internet.
        Inside IP=192.168.20.2
        Outside IP=10.0.0.3

B-GW  - Border gateway of central site.
        IP=10.0.0.1

INET  - Internet

R-PIX - PIX as border router of remote network.
        Inside IP=192.168.21.1
        Outside IP=10.10.0.2

R-Net - Remote network.
        Net=192.168.21.0/24

Now, what I want to do is first set up a tunnel between the 
two networks
(L-NET and R-NET). Computers on L-NET has a default gateway of
192.168.20.1, accessing Internet through FW. FW Provides 
access control
for these users. FW also has a static route to route traffic to R-NET
through the L-PIX.

Computers on R-NET has the PIX inside IP (192.168.21.1) as the default
gateway. All their traffic (including the traffic that should 
end up on
the Internet,) should be transmitted through the tunnel. For 
the client
traffic exiting the tunnel on L-NET, there needs to be a 
default gateway
set to 192.168.20.1, so that their Internet traffic also exits through
FW, and FW can provide access control for these users.

It is absolutely vital that the traffic does not exit directly to the
Internet at either PIX. All client traffic bound for the 
Internet *must*
be routed through the firewall at the central site (FW).

I've managed to set up a Site-to-Site VPN between the two PIXes,
establishing network connectivity between the two networks, but I have
found no solution to applying a default gateway for the traffic going
from the remote network to Internet. The traffic needs to be
source-routed in some way, or the clients on the remote 
network will not
be able to access the Internet (or any of the other routed 
networks I've
got set up here) at all.

Is this at all possible to do with two PIXes? As far as I can 
tell, the
remote PIX is doing what it should; forwarding *all* traffic 
through the
tunnel. But the local PIX doesn't know what to do with the packets to
the Internet, to it just drops them.

If this is not possible with the PIXes, could anyone recommend a
solution? I've done experiments with a Linux box with 
FreeS/WAN and got
that to work (using source routing), but I'd like to use a peripheral
for this job.

  // J


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