LARTC - Mar 2005 - Do I need NAT?

Yes, this is a dumb question.  I haven''t the time nor the resources to
dig into the guts of this right now, so perhaps someone will take a few
minutes to help, please.

I just implemented a classic "nano" multipath setup.  The script is at
http://yesican.chsoft.biz/lartc/rc.nano1

What I need to know is if I need SNAT in the firewall when a packet
comes in on the "wrong" interface.  If I do, please provide an example
"iptables -t nat" command and a description or diagram of what it
accomplishes.

ISP2 has a network address of 66.209.101.192/29 (eth2)
ISP1 has a network address of 206.72.89.152/29  (eth1)
In order to pass these to the 4 internal computers, eth0 has proxyARP
set.  Its IP is 206.72.89.158 and the eth0 NIC connects to a switch. 
The 4 internal computers have their eth1 NICs connected to that switch.

One of the internal machines, in this case the NNTP server, has an IP of
206.72.89.155.  When a packet is received from ISP1, is a NAT rule
necessary for that packet to get to the NNTP computer?
--
gypsy

OOPS!

I said "When a packet is received from ISP1, is a NAT rule
necessary for that packet to get to the NNTP computer?"

What I meant is ISP2, not ISP1.
--
gypsy