ip_local_deliver related query

Patrick McHardy kaber at trash.net
Tue Feb 7 15:47:02 CET 2006


Vasantha Kumar Puttappa wrote:
> Hi Patrick,
>   Thanks for your response. I have one more thing to clarify.
>   ( Sorry in the previous I made a great mistake, I wanted to change
>   destination IP address of the packet and not the source IP address).
> 
>   ( I am referring to first figure in the following link
>  http://www.linuxsecurity.com/resource_files/firewalls/IPTables-Tutorial/iptables-tutorial.html)
> 
>   If I am not wrong, NAT is being in done in PREROUTING AND POST-ROUTING
>  stage. But what I want to do is to take packets in FILTER INPUT stage and
>  change the destination IP address ( I don't want to create any SNAT
>  corresponding to that) and give it to local process.
>  (Assume that a socket waiting with that new destination address)

NAT is also done in LOCAL_OUT (DNAT) and LOCAL_IN (SNAT).

>   So, will there be any problem ?

No, it will work fine. Again: the socket lookups are done after the
netfilter hooks were called, so they will use the changed IP address.



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