Subject: Re: multihoming for SOHO lan
To: None <current-users@netbsd.org>
From: Paul Newhouse <newhouse@pimin.rockhead.com>
List: current-users
Date: 03/23/1999 22:51:15
Platform i386:
Wolfgang Rupprecht <wolfgang+gnus@dailyplanet.wsrcc.com> wrote:
> newhouse@pimin.rockhead.com (Paul Newhouse) writes:
> > I think I can solve this by having the cable traffic NAT'd into
> > a subnet, say 172.16.1.0/24. The subnet can be routed back to the
> > cable modem's DHCP assigned address.
>
> You have to worry about the return traffic from your machine back to
> the internet. If your routing table's route for a destination points
> one way, your packets are going to go in that direction, no matter
> what the source address is. If your ISPs filter by source address
> (like TCI/athome does) you really need to make sure the source address
> is correct for for the port you are going to send the packet out of.
>
> What you need is a way to route based on source address. Luckily
> ipfilter is up to this task. You need to use the "route" option to
> nudge the packets that were about to go out a bad port, back to the
> correct port. This is what I use:
>
> pass out log quick on de0 to de1:mygateway from 140.174.88.1/32 to any
Wow! It would have taken me a long time to come up with that based on the
manpage and the examples.
I'm pretty sure I don't understand exactly what this does. Let me take
a guess and PLEASE correct me where I go wrong.
quick
If a match then don't check any more rules. So I should put this after
any other de0 rules?
pass out on de0
This would be the cable modem port, where I really want it to go.
to de1:mygateway
This would be where it was going. The default route on de1 and the
default routes gateway address? The man page says:
"dup-to" interfacename[":" ipaddr]
I take it the "dup-" isn't necessary or in this case is wrong? Is the man page
not quite right?
from 140.174.88.1/32
This is the DHCP assigned address for the cable modem port?
to any
Meaning I'm responding to some arbitrary originator.
TIA,
Paul
204.219.89.41/29 +----------------+ +------+
---DSL connection---------|ne1 ex0|-----| W98 | 205.219.89.44/29
| router/switch | +------+ 172.16.89.44/24
| gateway |------others
0/32 | NetBSD box | +------+
--cable connection--------|ne0 de1|-----|NetBSD| 205.219.89.46/29
+----------------+ +------+ 172.16.89.46/24