public IP behind NAT system

public IP behind NAT system

[Mike McLean]

Hi,

I have a situation where I've setup a system that has one public IP and does 
NAT for a network of computers with private IPs.  However I wish to setup a 
couple of machines behind this NAT system with public IPs like the following:


outside router --> NAT system --> other systems with public IPs.

I am wondering if this is possible and feasable with netfilter.  I don't want 
netfilter to NAT any packets sent to the public IPs that aren't on the NAT 
system.

Any help is greatly appreciated,

Mike

RE: public IP behind NAT system

[Rob Sterenborg]

> outside router --> NAT system --> other systems with public IPs.
> 
> I am wondering if this is possible and feasable with 
> netfilter.  I don't want netfilter to NAT any packets sent to 
> the public IPs that aren't on the NAT system.
> 
> Any help is greatly appreciated,

If there are only "other systems with public IPs", then I'd say there's
no need for a "NAT system". The only thing you want to do would be
filtering ?
You can just allow forwarding for IP's that you want and route the
packets through your firewall.
If you also have other systems that have private IP's then you just NAT
those IP's, in addition to the above.


Gr,
Rob

Re: public IP behind NAT system

[Payal Rathod]

On Thu, Oct 02, 2003 at 11:20:10PM -0700, Mike McLean wrote:
> Hi,
> 
> I have a situation where I've setup a system that has one public IP and does 
> NAT for a network of computers with private IPs.  However I wish to setup a 
> couple of machines behind this NAT system with public IPs like the following:
> 
> 
> outside router --> NAT system --> other systems with public IPs.

Something like,
iptables -t nat -A PREROUTING -d <ext ip> -j DNAT --to <int ip>

might help.

-Payal

> 
> I am wondering if this is possible and feasable with netfilter.  I don't want 
> netfilter to NAT any packets sent to the public IPs that aren't on the NAT 
> system.
> 
> Any help is greatly appreciated,
> 
> Mike
> 
> 

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