splitting one network physically using linux box.

splitting one network physically using linux box.

[Daniel Rycaj]

hi,

I have a *very* standard situation:

network: 10.1.1.97/27

	   small router			10 PCs
	---[ 10.1.1.97 / 27 ] --------- [ 10.1.1.98-108 ]

Now I want to create a firewall between the "small router" and "10 PCs".
The only problem is: nobody should change configuration of PC. 
So the default gw still should be set to 10.1.1.97 on each PC.

I did such configuration:

	
	--[ 10.1.1.97 / 27 ] ----- eth0 [ linux box ] eth1 ------ [ 10.1.1.98-108 ]

eth1 must have assigned IP: 10.1.1.97 because I don`t want to change configuration of PCs.
eth0 can be set to one of unused addresses from 10.1.1.96 network (in my example 10.1.1.110)

I have to set up the default gw for my linux box to 10.1.1.97.
How to tell linux that he has to route packet through the external 10.1.1.97 rather the local one ? :)

I tried to do it by several ways:

1) ip ro add 10.1.1.97/32 dev eth0	- doesn`t work because 10.1.1.97 exists in table local

2) ip ro del 10.1.1.97/32 table local	- works fine for 1-2 minutes. After this short time
the local table contains .97 again !

Any ideas how to solve this ?

regards,
Daniel Rycaj

Re: splitting one network physically using linux box.

[Antony Stone]

On Tuesday 07 May 2002 10:07 am, Daniel Rycaj wrote:

> hi,
>
> I have a *very* standard situation:
>
> network: 10.1.1.97/27
>
> 	   small router			10 PCs
> 	---[ 10.1.1.97 / 27 ] --------- [ 10.1.1.98-108 ]
>
> Now I want to create a firewall between the "small router" and "10 PCs".
> The only problem is: nobody should change configuration of PC.
> So the default gw still should be set to 10.1.1.97 on each PC.

I can understand why you don't want to change the configurations of the PCs.

I there any REALLY GOOD reason why you can't change the configuration on the 
router ?

If you do not want to do that, you will end up with a pretty horrible and 
difficult arrangement on your Linux box.....

 

Antony.