Re: multiple mapping

["John A. Sullivan III" <jsullivan@opensourcedevelopmentcorp.com>]

On Wed, 2004-09-01 at 07:19, Tomek Macioszek wrote:
> Thanks for help. I have just only one question?
> If I make multiple mapping like this:
> iptables -t nat -A POSTROUTING -s 192.168.10.0/24 -o eth0 -j SNAT --to
> 4.3.2.0/24
> I should bind all this addresses (4.3.2.0/24) to eth0?
> ip address add 4.3.2.2/24 dev eth0
> ip address add 4.3.2.3/24 dev eth0
> ip address add 4.3.2.4/24 dev eth0
> ....
> ip address add 4.3.2.254/24 dev eth0
> Best regards
> T.
<snip>
If that is what you want to do, you will probably want to use the NETMAP
target from patch-o-matic.  The rule that you propose does not guarantee
a one-to-one mapping.  It does a round-robin mapping.  Thus there is no
guarantee that 192.168.10.5 maps to 4.3.2.5. In fact, it most likely
will not.

As far as I know, you will need to bind all of the addresses so that
they respond to the ARP requests.

This is where a tool like ISCS comes in handy
(http://iscs.sourceforge.net).  Not only does it automate the access
control configuration but it automates NAT and ARP.  You would simply
create a server with a private IP address of 192.168.10.1-192.168.10.254
and a public address of 4.3.2.1-4.3.2.254 and check the enforce
one-to-one box.  It would then create all the NAT rules, the address
bindings for ARP and distribute them to the gateway.  The project only
has pre-alpha releases thus far but we are moving quickly toward a full
release.  Good luck - John
-- 
John A. Sullivan III
Open Source Development Corporation
Financially sustainable open source development
http://www.opensourcedevel.com