Date: Fri, 10 Mar 2000 21:21:00 -0500 From: "Crist J. Clark" <cjc@cc942873-a.ewndsr1.nj.home.com> To: Alfred Perlstein <bright@wintelcom.net> Cc: Dennis Jun <dennisjun@yahoo.com>, freebsd-questions@FreeBSD.ORG Subject: Re: ARP errors? Message-ID: <20000310212100.C18898@cc942873-a.ewndsr1.nj.home.com> In-Reply-To: <20000309223544.D14279@fw.wintelcom.net>; from bright@wintelcom.net on Thu, Mar 09, 2000 at 10:35:44PM -0800 References: <20000310054234.2537.qmail@web605.mail.yahoo.com> <20000309223544.D14279@fw.wintelcom.net>
next in thread | previous in thread | raw e-mail | index | archive | help
On Thu, Mar 09, 2000 at 10:35:44PM -0800, Alfred Perlstein wrote:
> * Dennis Jun <dennisjun@yahoo.com> [000309 22:15] wrote:
> > Hello all! I'm a FreeBSD newbie, so please bare with me if
> > this question is very simple.
> >
> > I have a simple home LAN setup of 2 computers: one is
> > Windoze 98 and the other I recently installed with FreeBSD
> > 3.4-RELEASE. Furthermore, I am running natd on the BSD box
> > with two NICs. Both NICs are plugged into my hub and so is
> > my 98 box. Also, my cable modem is connected to the hub as
> > well (in the uplink port). So that's 4 connections going
> > into the hub total (2 from BSD, 1 from 98, & 1 from my
> > cable modem).
> >
> > My 98 box has the ip of 192.168.0.6. My BSD box has 2 ips,
> > one from the cable provider (on ed1, 24.xx.xx.xx) and the
> > other is 192.168.0.1 (on ed2).
> >
> > Now everything works fine. natd works great, so does named,
> > and the firewall as well. However, I get this annoying
> > message on my BSD box:
> >
> > /kernel: arp: 192.168.06 is on ed2 but got reply from
> > 00:c0:a8:50:9e:a7 on ed1.
> >
> > What does this exactly mean? and how do I correct it?
>
> A hub is a broadcast device, therefore both ethernet cards get
> the replies, the kernel is annoyed that you are set up like this
> because it's a misconfiguration.
For several reasons that I like to point out everytime I see someone
do this,
1) Your "firewall" is useless except for the box it is on. All
packets coming in from the outside are heard by every machine
on the hub.
2) You are decreasing your potenial bandwidth by having two NICs
from one host on the hub. The throughput on a hub is primarily
limited by collisions, and each NIC means more possible
collisions.
3) YOU are the guy leaking your RFC 1918 addresses out over the
cable modem all over your LAN! Very good chance all of your
"private" network traffic ain't so private.
> You ought to just plug the cable modem directly into one of
> the FreeBSD box's interfaces.
Amen, brother.
--
Crist J. Clark cjclark@home.com
To Unsubscribe: send mail to majordomo@FreeBSD.org
with "unsubscribe freebsd-questions" in the body of the message
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?20000310212100.C18898>