Re: dhcp && cable modem (somewhat urgent)

["Joe Emenaker" <jemenake@blastpoint.com>]

> Question:  How do you get the dhcp client on my firewall computer to grab
the
> cable modem address and not an address from my internal dhcp?

If you are going to have two have two ethernet cards in your machine, this
is fairly easy and a number of responses have already touched on how to have
dhcpcd listen on only one card.

If you're like me, and you use one card in the box at all, then it gets a
little more fun. What it requires is one of those cable modems that
"marries" the first ethernet card it sees. Here in central CA, our provider
uses General Instruments SurfBoard modems. The first DHCP request they see,
the memorize the hardware address of that card and that's the only thing
they'll listen to is *that* card. That will keep other machines on your
home-net from getting the IP address.

Then, all you have to do is make sure that your linux box doesn't get its IP
address from the *other* DHCP server. There are two ways to do this.

 1 - If your other DHCP server *is* you linux box, you probably have nothing
to worry about, but, just to be safe, you can probably launch your DHCP
daemon *after* you get an IP address from the modem by putting
"/etc/init.d/dhcp start" in your /etc/dhcpcd/ip-up script (or whatever it's
called).

 2 - If your other DHCP server is *not* the linux box that is going to be
talking to the cable-modem, then just hard-code 1-to-1 mappings in your
dhcpd.conf file so that it only gives out certain IP's to hardware addresses
that it recognizes.

- Joe