Date: Tue, 22 Aug 2000 22:12:02 -0700 From: "Crist J . Clark" <cjclark@reflexnet.net> To: "Larry Skarpness Jr." <larry@chainsoft.com> Cc: Emmanuel Gravel <egravel@earthlink.net>, freebsd-questions@FreeBSD.ORG Subject: Re: ARP issues with 2 or more multi-homed interfaces on same physical LAN Message-ID: <20000822221202.I28027@149.211.6.64.reflexcom.com> In-Reply-To: <001401c00c5d$040da9b0$0a00a8c0@chainsoft.com>; from larry@chainsoft.com on Tue, Aug 22, 2000 at 10:18:39AM -0700 References: <Pine.BSF.4.10.10008220246190.2305-100000@parmenides.utp.net> <200008220514.WAA24408@avocet.prod.itd.earthlink.net> <001401c00c5d$040da9b0$0a00a8c0@chainsoft.com>
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On Tue, Aug 22, 2000 at 10:18:39AM -0700, Larry Skarpness Jr. wrote:
> OK. I'm getting some great responses here. I appreciate the effort. Let
> me explain futher.
>
> In this case the cable modem does not leak my private network traffic. It
> appearently only transmits packets that it can route. It only allows the
> IPs that my ISP has given me to connect with it. I can actually verify this
> by watching the transmit LED, and it does not light during private network
> activity.
Most activity lights only come on during transmit, not receive. It is
quite possible your packets go out, but obviously, nothing gets routed
back. You could test this by sending stuff out to a routable
blackhole.
> I've also never seen anyone elses private network packets come
> across.
Do you ever see anything that is not destined for you (to your address
or broadcasts)?
> Remember that I must connect TWO different machines via the same cable
> modem, and the only way to do this is with a hub.
I'm not clear why this must be done.
> These same two machines
> must also be on the private net. I did start out with just NICA in Machine
> 1 (FreeBSD), but then my Firewall and NAT did not work properly (or was
> exceedingly complex to deal with) because of issues being on the same
> interface. So I abandoned that fiasco and went to the two NIC
> configuration.
How about,
}
Internet }---:nicA[ Machine1 ]nicB:---[ Hub ]
} | |
| |
| Machine3
|
Machine2
Where Machine1 is doing NAT,
interface nicA
redirect_address ipD ipC
And Machine2 and Machine3 have only their private net addresses, ipD
and ipE respectively.
[snip]
> > >Machine 1 has
> > > NICA HUB1
> > > IPA NETA (cable modem1) supports NAT to outside
> > > NICB HUB1
> > > IPB NETB (local1)
> > >Machine 2 has
> > > NICC HUB1
> > > IPC NETC (cable modem1)
> > > IPD NETB
> > >Machine 3 has
> > > NICD HUB1
> > > IPE NETB
> > >Cable mdem 1 on HUB1
> > >
> > >I think this is a valid configuration. Machine 1 complains that ARPs on
> > >NICA are picked up on NICB, which in this situation would be expected.
> Is
> > >there some reason why the FreeBSD OS must be so noisy about it? I WANT
> two
> > >or more NICs in the same machine on the same physical network. The hack
> I
> > >made to if_ether.c forces the OS quiet about it. Others are in the same
> > >situation and would probably like this option without the neccessity to
> > >hack.
> > >
> > >Larry
> >
> >
--
Crist J. Clark cjclark@alum.mit.com
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