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

-wolfgang
-- 
       Wolfgang Rupprecht <wolfgang+gnus@dailyplanet.wsrcc.com>
		    http://www.wsrcc.com/wolfgang/
DGPS signals via the Internet  http://www.wsrcc.com/wolfgang/gps/dgps-ip.html