Re: port forward with the ipmasq package and Iptables

[Tarragon Allen <melange@n12turbo.com>]

On Tuesday 29 April 2003 09:40, Tom Goulet (UID0) wrote:
> Hello,
>
> How do I forward port a port on the external IP to the same port on an
> internal IP?  I am using the ipmasq package and Iptables.  I'm willing
> to abandon the ipmasq package.

You shouldn't need the ipmasq package, NAT has been built into iptables for 
ages.

A rule like this should do the trick:

iptables -t nat -A PREROUTING -p tcp -d $external-ip --dport $external-port \  
-j DNAT --to $internal-ip:$internal-port

You will probably need a rule like this as well:

iptables -t nat -A POSTROUTING -o $external-ip -s $internal-ip -j MASQUERADE

$internal-ip in the last one can be changed to the network range, and will 
allow general NAT for that network.

t
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