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Date: Sat, 27 Jun 2015 10:50:07 +0200 From: Francois Romieu <romieu@...zoreil.com> To: Andy Lutomirski <luto@...capital.net> Cc: Network Development <netdev@...r.kernel.org> Subject: Re: Why can't we SNAT (or inverse DNAT) in PREROUTING? Andy Lutomirski <luto@...capital.net> : > On Fri, Jun 26, 2015 at 3:48 PM, Francois Romieu <romieu@...zoreil.com> wrote: > > Andy Lutomirski <luto@...capital.net> : [...] > >> Shouldn't the order of operations be: > >> > >> 1. Check rp_filter. > >> 2. Handle NAT. > >> 3. Routing decision. > >> ? > > > > The admittedly painful fwmark part would still be needed for pre-NAT > > source address based policy routing (assuming SNAT loses valuable policy > > information). Life would be easier for your current requirements but > > some different policy requirements would be unable to avoid the > > fwmark/mangle style stuff. > > What kind of policy routing would care about the pre-NAT source > address? AIUI, the usual use of policy routing is to *route*, not to > filter. But maybe I'm missing something. ? The same could be said regarding your (post NAT) source address policy routing requirement. > > Btw, the suggested scheme implies that filtering between SNAT and DNAT > > would be done before routing, thus without INPUT vs FORWARD tainting. > > What do you mean by "filtering between SNAT and DNAT"? I had Jan Engelhardt's netfilter packet flow diagram in mind. Replacing it with a 3 steps packet processing conceptual flow does not seem trivial to me. -- Ueimor -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
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