Re: forward/proxy/something one external IP to an other

[Brian Austin - Standard Universal <brian@standarduniversal.com.au>]

Grant Taylor wrote:
> On 09/26/08 11:50, Jan Agermose wrote:
>> we are going to move some servers from one datacenter to an other and 
>> not all DNS are under our direct control so Im want to place a linux 
>> box in the old center to forward trafic for the old IPs to the new 
>> IPs - or Im hoping this is possible :) So that traffic going to the 
>> old IPs will still work until all DNS is updated.
>
> Ok...
>
>> The servers are on a NAT 1-1 network and are moved to a new 1-1 NAT 
>> network - if this matters?
>
> Should not matter.
>
>> Can someone explain if its possible and how to do it?
>
> Yes it is possible.  You will need to DNAT the traffic as it comes in 
> to the nat:PREROUTING chain to redirect it over to the real server as 
> well as SNAT the traffic as it leaves the nat:POSTROUTING chain so 
> that the traffic appears to the real server as if it is coming from 
> the NATing server.  By making the traffic appear as being from the 
> NATing server the real server will reply back to the NATing server 
> which can then unNAT the traffic and reply directly back to the real 
> client.
>
> Or, you could run something like rinetd which will accept the 
> connections and then proxy them to the real server.  This is extremely 
> easy to set up too.
>
>
>
> Grant. . . .
> -- 
> To unsubscribe from this list: send the line "unsubscribe netfilter" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
I think like this...

       iptables -t nat    -A PREROUTING -d 192.168.19.253 -i eth19 -p 
tcp  --dport 993 -j DNAT --to-destination 192.168.41.5:993

       iptables -t nat -A  POSTROUTING -d 192.168.41.5 -j MASQUERADE