Port forward to public IP's behind firewall

Port forward to public IP's behind firewall

[Gareth Hastings]

[-- Attachment #1: Type: text/plain, Size: 464 bytes --]

I am using proxy arp and ip aliasing with iptables as a firewall for a few
class C networks. It works with no problems. All our machines behind the
firewall have public addresses. Now I would like to add a port forward rule
that sends all incoming mail to another IP address. I am not sure what I'd
need to do. I didn't think SNAT or DNAT were needed here as no NAT is
happening. Anyone have any ideas? Do I need to mangle the destination
address?

Thanks

Gareth

[-- Attachment #2: Type: text/html, Size: 864 bytes --]

Re: Port forward to public IP's behind firewall

[Nils Juergens]

On Thu, 04.09.03, Gareth Hastings <Gareth.Hastings@netcall.com> wrote:

> firewall have public addresses. Now I would like to add a port forward rule
> that sends all incoming mail to another IP address. I am not sure what I'd
> need to do. I didn't think SNAT or DNAT were needed here as no NAT is
> happening. Anyone have any ideas? Do I need to mangle the destination
> address?

If you send packets to another IP address why exactly is that not DNAT?

Try:

iptables -t nat -A PREROUTING -p tcp -d $fw_ip --dport 25 -j DNAT --to $target:25

cya,

Nils