[TriLUG] DHCP and Road Runner

Steve Litt slitt at troubleshooters.com
Sun Apr 28 14:11:56 EDT 2013


On Sun, 28 Apr 2013 11:14:04 -0400
Sean Alexandre <sean at alexan.org> wrote:

> I'm trying to configure a Debian box as my main router, attached to
> my cable modem from Road Runner. I can't DHCP to work, though. I
> don't get an IP address. 

Do you mean you can't get your router to work as a DHCP *client*, or
you can't successfully get a DHCP server on your router to act as a
DHCP *server* to the rest of your LAN?

If the latter, why not put a DHCP server on one of your other Linux
computers, at least as a temporary fix.

If the former, be sure your router's Internet facing NIC is configured
to get its address via DHCP. Assuming it hasn't yet been compromised
from its brief connection to the Internet without protection, you could
even connect it to a LAN with a known good DHCP server and see if it
gets an address. If so, it's likely that the problem's on your ISP's
end.

Now here's a little factoid I got from Brighthouse, that not everyone
knows. With my Brighthouse modem, and maybe with your ISP supplied
connection or equipement, you can't just disconnect something from the
modem, replace it with something else, and expect it to work, because
their modem remembers what it was connected to and says "hey, he
plugged in the wrong thing, I'm not going to deal with it!"

Here are the instructions Brighthouse gave me for switching boxes
connected to their modem (in other words, switching from your old
router to your new one):


    Power down your old router/firewall
    Power down modem
    Wait 30 seconds
    Power up modem
    Wait til the cable light is on solid
    Power up the new firewall/modem, wait til you get an address


Thanks,

SteveT

Steve Litt                *  http://www.troubleshooters.com/
Troubleshooting Training  *  Human Performance



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