[BLU] Re: RoadRunner and multiple computers

David Kramer david at thekramers.net
Wed Mar 14 11:21:57 EST 2001


On Wed, 14 Mar 2001, Chris Janicki wrote:

> This isn't a direct Linux question, but I'm sure of you have the
> expertise with cable Internet service...
>
> RoadRunner offers a 1-computer and 3-computer option (you supply your own
> hub).  Does anyone know how this hardware works?... can I place a router
> in front of the 1-computer cable modem and extend the service?  Or does
> the cable modem keep track of sessions or ethernet MAC addresses to limit
> service?  Or is the real problem getting a fixed IP address to route through?

RoadRunner cablemodems do, in fact, record the first mac address they see
when reprogrammed, and will only talk to that mac address afterwards.  A
record of it is also sent to RR.  What you want to do would expose all
your boxen to the internet for happy hackers, anyway.

The correct thing to do is this:

                DHCP         192.168.1.1       <--> 192.168.1.2 ws
cablemodem <--> ethx             ethy <--> hub <--> 192.168.1.3 ws
                linux firewall/IPMASQ          <--> 192.168.1.4 ws

The cablemodem connects to one NIC card in your linux firewall/IP
Masquerade box, and uses DHCP to get it's real-world address.  The hub
connects to the other NIC card in your linux box, and has a intranet IP
address (io 10.0.0.1, or 192.168.1.1, etc).  Each

If you stay with this model exactly, your servers are on the intranet side
of the linux box, and you mus use IP forwarding to pass connections
through to it.  Some people, like me, take a slight risk and run my
outbound servers right on the firewall.

-------------------------------------------------------------------
DDDD   David Kramer                   http://thekramers.net
DK KD
DKK D  "All my life, I always wanted to be somebody.
DK KD  Now I see that I should have been more specific."
DDDD                                       - Lily Tomlin



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