many one-to-one NAT

many one-to-one NAT

[Yaron Presente]

Hi All,
I'm a newbie to this list and I apologize if this question has already 
appeared in previous posts.
I would like to do NAT from a private range to a public range of the 
same size, in a way that just
the network part of the IP address would be translated.
For example, I would like a single iptables rule to map 192.168.10.0/24 
=> 10.1.1.0/24 as follows:
192.168.10.1 => 10.1.1.1
192.168.10.2 => 10.1.1.2
.
.
.
192.168.10.254 => 10.1.1.254

I know that I can do it by defining the whole set of rules explicitly, 
but I'm looking for a better solution in terms of simplicity and 
performance.
Can anyone help?
Thanks,

-- 
Yaron Presente
MRV International
Direct   : 972-4-9936237
Fax      : 972-4-9890564
Email   : ypresente@mrv.com
www.mrv.com

Re: many one-to-one NAT

[Philip Craig]

Yaron Presente wrote:
> I would like to do NAT from a private range to a public range of the 
> same size, in a way that just
> the network part of the IP address would be translated.

Use the NETMAP target.  This is included in 2.6, but I think you have to
patch 2.4 kernels still.

> For example, I would like a single iptables rule to map 192.168.10.0/24 
> => 10.1.1.0/24 as follows:
> 192.168.10.1 => 10.1.1.1
> 192.168.10.2 => 10.1.1.2
> .
> .
> .
> 192.168.10.254 => 10.1.1.254

Assuming 192.168.10.0/24 is private:

iptables -t nat -A PREROUTING -d 10.1.1.0/24 -j NETMAP --to 192.168.10.0/24
iptables -t nat -A POSTROUTING -s 192.168.10.0/24 -j NETMAP --to 10.1.1.0/24

-- 
Philip Craig - SnapGear, A CyberGuard Company - http://www.SnapGear.com