On Sun, 9 Dec 2001, Peter Mancuso wrote:

> So would perhaps changing my subnet interface to a more obscure subnet
> address ?.?.?.?\24 , or one thats different then my brothers help at
> all?.....okay wait I did not mention this.....our cable modem is directly
> connected to the uplink port on a hub....then we both plug into that hub for
> internet access (my rl0)...I dont know if that has anything to do with
> it....since our subnets are on different  interfaces I though they will not
> clash....

Ok, Is this what you are saying:

                          IP A         192.168.1.1  192.168.1.2
[Cable Modem]---[Hub]-------[rl0: Your box :ed0]------[other machine]
                  |
                  *------[Brothers machine]-------[other machine(s)]
                       IP B              192.168.1/24

Where IP A and IP B are real IP addresses assigned by your provider?
This situation should be OK.  Since the cable modem is a dumb ethernet
bridge, you want to make sure you don't have any traffic on the same
network as the cable modem which isn't actually intended to go out the
modem (may work, but could cut eat up your bandwidth).

So if you are seeing ARP replys for the 192.168.1/24 network on the rl0
interface, there are a couple of possibilities:
- your brother's machine is doing something wrong and sending ARP packets
out the wrong interface (is it NetBSD or FreeBSD also?)
- your machine is doing something wrong by sending the ARP request out the
wrong interface (doubtufll)
- or you're receiving the ARP packets from the cable due to someone else
using that IP range directly connected to their cable modem.

You should be able tell by comparing the MAC address in the error message
to the MAC addresses of your other machines.  If none of the machines in
your house use have that MAC address, then it must be coming over the
cable modem.

When I used to have a cable modem, I had a problem with receiving ARP
packets off the network (I was using 192.168.0/24).  However, I don't
think I got the same error message.  Is this the only message you see?  I
think I just got something like "error adding ARP entry for ...".  Your
message seems to suggest you sent out an arp request on ed0 and
immediately got a response on rl0.  Anyway, once I discovered someone
else on my cable-modem segment was using the 192.168.0/24 range connected
directly to their cable modem, I simply chose a less common address range
(192.168.149/24) and my problems went away (although I may have still
got warnings about unexpected ARP packets on the interface)...

Hope this helps,
	Rick