RE: Is it possible to forward broadcasting with IPtables?

["John A. Sullivan III" <john.sullivan@nexusmgmt.com>]

I've neither tried it nor thought it through but would the NAT
capabilities of iproute2 help here? Will iproute2 change the address
before Netfilter makes a decision of which filter table chain to use? -
John

On Wed, 2004-04-07 at 11:19, Younger Wang wrote:
> I tried DNAT in PREROUTING. 
> 
> Take an example: 
> The broadcasting is send from 10.0.0.22/24 to 10.0.0.255/24. I want the
> router( 10.0.0.1, 192.168.0.1 ) to forward it as from 10.0.0.22/24 to
> 192.168.0.255/24. 
> 
> I added:
> Iptables -t nat -A PREROUTING -p udp -d 10.0.0.255 --dport 137 -j DNAT
> --to-destination 192.168.0.255
> 
> The result is: 10.0.0.22-->10.0.0.255 was changed to
> 10.0.0.22-->192.168.0.255 in PREROUTING. Later on, in routing decision,
> it's still put to the INPUT chain because the router also listens to
> 192.168.0.255. That's the reason why DNAT in PREROUTING does not work
> and why I want to transfer the packet from INPUT chain to forward chain.
> 
> 
> BR
> Younger Wang
> 
> -----Original Message-----
> From: netfilter-admin@lists.netfilter.org
> [mailto:netfilter-admin@lists.netfilter.org] On Behalf Of Antony Stone
> Sent: Wednesday, April 07, 2004 7:15 PM
> To: netfilter@lists.netfilter.org
> Subject: Re: Is it possible to forward broadcasting with IPtables?
> 
> On Wednesday 07 April 2004 12:07 pm, Younger Wang wrote:
> 
> > If the broadcast packets traverse the chains, they should be put to
> > INPUT chain. Is there a way to transfer a packet from INPUT chain to
> > FORWARD chain?
> 
> DNAT in PREROUTING?
> 
> In theory this would do what you want, however I'm sure it won't work.
> 
> Regards,
> 
> Antony.
-- 
John A. Sullivan III
Chief Technology Officer
Nexus Management
+1 207-985-7880
john.sullivan@nexusmgmt.com