Connection to backbone

[Ray]

On Mon, 11 Jun 2001, Ramin Alidousti wrote:

> So, if a public IP is configured on the box, why is it not the one
> which connects you to the outside world and why are you then using
> a private IP for this purpose?

Because the public IP connects to my internal network.  I have a class B
public network, i'm not doing any NAT here..  Perhaps a diagram would
help, xxx.xxx denotes the public network:

 -------------------- 
|                    |
|   xxx.xxx.0.0/16   |
|    Core switch     |
 -------------------- 
         |
         |
         |xxx.xxx.1.1/16
   ---------------
   |             |
   | Linux fw    |
   |             |
   ---------------
         |10.0.0.1/30
         |
         |10.0.0.2/30
   ---------------
   |             |
   |  Cisco      |
   |             |
   ---------------
         |yyy.yyy.yyy.yyy (some IP given by my ISP)
         |
         |
    (---------)
   (           )
  (  internet   )
   (           )
    (---------)

Before i put up the Linux firewall, the Cisco had the xxx.xxx.1.1/16
address.

So you see, packets leaving the OUTPUT chain destined for the internet
have a src ip of 10.0.0.1.  They make it to the Cisco, but are meaningless
on the internet.

I may try Vik's idea of using iproute2 to change the src address, but this
also sounds a little "hackish".  I think the cleanest way is to use a
small public subnet between Linux fw/Cisco.  Comments?

-Ray
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Ray DeJean  				       	 http://www.r-a-y.org
Systems Administrator               Southeastern Louisiana University
IBM Certified Specialist  	      AIX Administration, AIX Support
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