RE: Firewalls, PC static routes, gateways

From: John F. Appel (jfaat_private)
Date: Mon Jan 03 2000 - 12:12:50 PST

  • Next message: Rodney van den Oever: "Re: Firewalls, PC static routes, gateways"

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    Randy,
    
    Cleanest way is to have a second internal router inside the firewall,
    which then becomes the default gateway for the internal network. 
    Your end picture looks like this:
    
    
    	|----------|
    	| Internet |
    	|  router  |
    	|----------|
    		|
    		|
    		|
    	|----------|
    	| Firewall | <--- This will probably need 
    	|----------|	static routes to all of 
    		|		internal networks, including
    		|		those via the alternate GW
    		|
    	|----------|		|---------|			|---------|
    	| Internal |------------|   LAN   |-------------|Alternate|
    	|  router  |		|---------|			| Gateway |
    	|----------| 						|---------|
    		^
    		|		This becomes default 	
    		|----------	gateway for your LAN; uses
    				inside interface of FW as
    				default GW
    
    
    	Used and working in a number of places. 8-)  Of course, this assumes
    that what's beyond the alternate gateway is trusted (or that you can
    make management care if it isn't fully trusted...)
    
    Cheers,
    
    John
    
    John Appel
    Sphere Solutions, Inc.
    410-552-4077 x452
    jfaat_private
    
    PGP public key available 
    								
    > -----Original Message-----
    > From: owner-firewall-wizardsat_private
    > On Behalf Of Randy Witlicki
    > Sent: Sunday, January 02, 2000 6:44 PM
    > To: firewall-wizardsat_private
    > Subject: Firewalls, PC static routes, gateways
    > 
    > 
    >    Hello,
    > 
    >    I'm wondering if anybody has come up with a reasonable
    > solution to static routes for Windows 95/98/NT laptop users
    > in networks with a firewall and *another* gateway.
    >    If we have a setup where:
    >     - The default route points to the firewall on the local
    > network, and;
    >     - You need an additional route to point to a gateway for
    > some private network (either via VPN or a private (leased line
    > or frame relay) link).
    >     (e.g.: the route to 0.0.0.0 is 10.0.0.1 and the route to
    > 172.16.0.0/16 is 10.0.0.2)
    > 
    >    Specific problems I have run into include:
    > 
    >    - With a PIX firewall, even you don't mind having packets
    > bounce off the PIX inside interface, it won't let you.  If you
    > have a "route inside" statement, you get an error of the form:
    >     106011: Deny inbound (No xlate) tcp
    >          src inside:X.X.X.X/1047 dst inside:Y.Y.Y.Y/23
    >      Which is the PIX's way of saying it refuses to receive a
    > packet on the inside interface and resend it to a gateway
    > on the inside.  So you need a route on each host inside.
    > 
    >    - If you have a "route add" in a startup .BAT file on a 95 or
    > 98 PC or a "route add -p" on an NT PC, if it is a laptop and that
    > laptop travels to the remote network the "route add" is pointing
    > at, then you need a .BAT file to reverse the startup .BAT file.
    > I assume you might have similar problems with a *nix laptop.
    >     Is there a way to get one of these systems to listen to
    > RIP or something similar ?
    >     I think I can do this with DHCP, but at least one of the
    > networks involved is very small and it would be nice to avoid
    > having to to setup a DHCP server (and having one more server
    > piece to depend on).
    > 
    >    Thanks in advance for any advice and help !
    > 
    >     - Randy
    >    -
    > 
    > 
    
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