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Date:	Sun, 24 Jun 2007 21:58:54 +0200 (CEST)
From:	Jan Engelhardt <>
To:	Kyle Moffett <>
cc:, LKML Kernel <>,
	Andrew Morton <>,
Subject: Re: Scaling Max IP address limitation

On Jun 24 2007 15:08, Kyle Moffett wrote:
> Do you really need that many IP addresses?  When somebody finally gets
> around to implementing REDIRECT support for ip6tables then you could
> just redirect them all to the same port on the local system.

The way I see it, it's: "if someone gets around to implement *IPv6 NAT*"
(which, if its designers were asked, is contrary to the idea of ipv6).

> <Unrelated wishful thinking>
> I keep having hopeful dreams that one day netfilter will grow support for
> cross-protocol NAT (IE: NAT a TCPv4 connection over TCPv6 to the IPv6-only
> local web server, or vice versa).  It would seem that would require a merged
> "xtables" program.
> Having routing table operations, IPsec transformations, etc just be
> another step in the firewall rules would also be useful.  It would be
> handy to be able to "-j ROUTE", then "-j IPSEC", then "-j ROUTE" again,
> to re-route the now-encapsulated IPsec packets to their proper
> destination.


> That would also eliminate the sort-of-hacky problems with
> destination network interface in the bridging code:

Where's the hack? iptables operates on what it sees, and it sees br0.
The physdev match is justified IMO.

> "-j BRIDGE" might be
> another step in the process, and conceivably you could have independent
> bridge MAC tables too.

Whether a packet goes out a bridge (was that the intention of -j BRIDGE?)
is determined by the routing table, which, in most cases, is just a matter
of destination address.

> You'd probably also want "-j BRIDGE_TEST" and
> "-j ROUTE_TEST" to compute the output network interface without actually
> modifying the addresses.
> That would also appear to get rid of the need for all tables other than
> "filter" and all predefined chains other than "INPUT" and "OUTPUT".  Default
> rules would be these:
> nettables -A INPUT -j CONNTRACK
> nettables -A INPUT -j LOCALMATCH
> nettables -A INPUT --for-this-host -j ACCEPT
> nettables -A INPUT -j OUTPUT

I'd prefer if Linux outputted its packets by default :)

> nettables -A OUTPUT -j ROUTE
> nettables -A OUTPUT -j TRANSMIT

pkttables it is!

But this idea may have its benefit: by not restricting rules to certain
positions like currently, throughput could be achieved. "Evil packets"
f.e. could be dropped really early. (Well, you could also drop them early
_today_, but a DROP in the mangle table will everyone make their eyes roll

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