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Re: linux routing



On Tue, Apr 25, 2000 at 05:00:31PM -0700, Kevin wrote:
> Well apparently my art career wasnt as promsing as I thought.  I'll try
> again:
> 
> internet ->eth0 -> 38.185.233.175 -> eth1 -> box1 (38.185.233.176) and box2
> (38.185.233.177)

Assuming you've been assigned a subnet and not a few static IPs this
should be relatively straightforward.  However, if the IPs you give
are accurate I'm not sure you've been assigned a subnet.

Let's assume that you have, and the subnet in question is 38.185.233.160/27
(unlikely, since that's a 32 address subnet; however it's the only one
I could think of that contains your addresses).

In that case you'd set up your router like this:

  eth0 -> whatever the external IP is
  eth1 -> 38.185.233.175

routing table on router:

  default route gw [next hop for eth0]

box1 and box2 would list 38.185.233.175 as their default gw.

The next hop at the ISP also needs a route for network 38.185.233.160/27
pointing to the IP for eth0.

I suspect that the above is all smoke and you've actually been assigned
three IP addresses.  You naturally want to place two of them behind a
linux firewall.  To do this you're going to have to configure
bridging.  In this scenario eth0 has IP address 38.185.233.175, but it
also performs proxy ARP for 38.185.233.176 and 38.185.233.177.  router
then forwards all packets out eth1 so box 1 and box2 can communicate
with the world.

I have never set up bridging in linux; I'm ashamed to admit I'm all to
familiar with bridging using "real" routers like Bay or Cisco gear ...

I don't want to say more until I have a clearer idea of what you are
trying to do and what your situation is.

-- 
Nathan Norman         "Eschew Obfuscation"          Network Engineer
GPG Key ID 1024D/51F98BB7            http://home.midco.net/~nnorman/
Key fingerprint = C5F4 A147 416C E0BF AB73  8BEF F0C8 255C 51F9 8BB7

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