Re: transparent proxy with iptable redirect

[Pascal Hambourg <pascal@plouf.fr.eu.org>]

Peter Chen a écrit :
> I have a pretty straightforward question that I've been wondering. If
> I add an iptable redirect rule (e.g. dst tcp port 80 to tcp port
> 8080), it would change every tcp packet with port 80 as its
> destination to a tcp packet with destination 8080. Now if my
> application listening on 8080 were to reply to the source, it would
> transmit a tcp packet with src port 8080, but the source side is
> expecting a tcp packet with src port 80.
> 
> So my question is, how does the reverse path from dest back to the
> src, at what point does the port number get rewritten from 8080 back
> to 80, making the redirect transparent? Is this done by iptable
> automatically on a redirect target?

Yes. Stateful NAT takes care of both directions of the connection.