Re: Change source address on incoming packets

[Joel Vosu <joel.vosu@mail.ee>]

Antony Stone wrote:

>On Sunday 09 May 2004 10:50 pm, Joel Vosu wrote:
>
>  
>
>>I would need to be able to change the source address of incouming
>>packets. I have 2 different subnets, but I need the server to see the
>>packes from the 2nd subnet as coming from the 1st.
>>in iptables it would be something like:
>>iptables -A PREROUTING -t nat -s 2nd_subnet -j SNAT --to-source
>>local_machine
>>but this is not possible because SNAT only works for outgoing packets in
>>POSTROUTING.
>>Is there a way to get this to work other than adding a second router box
>>for NAT?
>>    
>>
>
>The only way I can think you'd be able to do this on one box is by hacking 
>around the source for netfilter so you can use SNAT in PREROUTING.   You'd 
>need to be careful about the auto-reverse NAT for reply packets, as well, to 
>make sure they go back to the original machine.
>
>Not impossible, by any means, but it's almost certainly easier to dig up an 
>old 486 or Pentium and run NAT on that.
>
>Regards,
>
>Antony.
>
>  
>
Thanks Antony,
But since I'm not that good at hacking source I hope I'll still find an 
easyer solution. As for the 486 or pentium part... if I cant find 
anything by tomorrow morning I'll have to use that. Right now I'm 
checking proxy applications if they can do what is required.

Joel