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Date:      Thu, 6 Jun 2002 13:55:41 +0200
From:      Axel Scheepers <axel@axel.truedestiny.net>
To:        Joe & Fhe Barbish <barbish@a1poweruser.com>
Cc:        FBSDQ <questions@FreeBSD.ORG>
Subject:   Re: dhcp client and cable modem
Message-ID:  <20020606135541.C67863@mars.thuis>
In-Reply-To: <MIEPLLIBMLEEABPDBIEGAEADCCAA.barbish@a1poweruser.com>; from barbish@a1poweruser.com on Wed, Jun 05, 2002 at 10:00:53AM -0400
References:  <MIEPLLIBMLEEABPDBIEGAEADCCAA.barbish@a1poweruser.com>

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On Wed, Jun 05, 2002 at 10:00:53AM -0400, Joe & Fhe Barbish wrote:
> I'm using the FBSD built in dhcp client on the Nic card to the cable modem.
> My ipfw firewall is denying a bunch of packets which never happened
> with the modem connection.
> 
> Could somebody tell me what ipfw rules I need to allow the cable isp
> dhcp server to correspond with my FBSD gateway?

DHCP broadcasts to 255.255.255.255 so every host on the subnet can answer
to it's request. The traffic originates from 0.0.0.0 (your unconfigured nic)
port 68 and goes to 255.255.255.255 port 67.
One of the dhcp servers will respond to this cry out for help and answer
to the ip address you'll get on port 67 from the servers ip port 68. So the
second rule will be quite open since you can't tell what you'll get and have
to specify any address here.

> 
> A pointer to some documentation on what packets get exchanged would be
> great.

http://www.isc.org/products/DHCP/dhcpv3-README.html#firewall

Describes it.

> 
> Thanks  Joe
> 
> 

Gr,
-- 
Axel Scheepers
UNIX System Administrator

email: axel@axel.truedestiny.net
       a.scheepers@iae.nl
http://axel.truedestiny.net/~axel
------------------------------------------
I am not now, nor have I ever been, a member of the demigodic party.
		-- Dennis Ritchie
------------------------------------------

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