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Date:      Wed, 9 Mar 2016 18:48:06 +0100
From:      Franco Fichtner <franco@lastsummer.de>
To:        Don Lewis <truckman@FreeBSD.org>
Cc:        freebsd-ipfw@freebsd.org
Subject:   Re: ipwf dummynet vs. kernel NAT and firewall rules
Message-ID:  <DA540940-CED7-4E2E-8E1D-5088A140F2CB@lastsummer.de>
In-Reply-To: <201603091733.u29HX05o011028@gw.catspoiler.org>
References:  <201603091733.u29HX05o011028@gw.catspoiler.org>

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Hi Don,

If you mean pf(4)-based NAT, there is a patch that originates from
m0n0wall that handles the transition.  We're using it in OPNsense
for that reason.  Here is the patch for 10.x, maybe that is what
you're looking for:

https://github.com/fichtner/freebsd/commit/975130903f.patch

We would very much like to upstream this eventually, but are not
sure what is needed (on/off switch via sysctl(8) was discussed
internally but could be crude).  It seems useful to have in some
instances.  Combining ipfw(4) and pf(4) has proven to be tricky,
where even execution order of both of them matters in pfil(9).


Cheers,
Franco

> On 09 Mar 2016, at 6:32 PM, Don Lewis <truckman@FreeBSD.org> wrote:
> 
> I'm trying to add FQ-CoDEL AQM to my FreeBSD 10 firewall box using this
> patch: <http://caia.swin.edu.au/freebsd/aqm/downloads.html>, but I'm
> running into a problem that I think is caused by an interaction between
> in-kernel NAT and dummynet.  I've set up two dummynet pipe/sched/queue
> instances using example 3.3a from this document
> <http://caia.swin.edu.au/freebsd/aqm/patches/README-0.1.txt>; with the
> appropriate bandwidths, but otherwise default tunings to shape both
> inbound and outbound traffic.  My inside network is a /24 and I have an
> external /29 (ext/29) network that I don't want to rate limit.  My
> outside network interface is re0.  I'm using the /etc/rc.firewall
> "simple" firewall configuration.
> 
> The problem that I'm having crops up when I actually try to add the
> firewall rules to select the traffic that I want to rate limit.  The
> first rule in the list is:
> 	100 allow ip from any to any via lo0
> The second rule is numbered 200 and is first anti-spoofing rule.  If
> I add *either* of these two rules, then I'm no longer able to
> communicate between hosts on my internal network and the rest of the
> world:
> 
>  ipfw 110 add queue 1 ip from not ext/29 to any in recv re0
>  ipfw 120 add queue 2 ip from any to not ext/29 out xmit re0
> 
> It seems like the inbound rule should be early in the rule list so that
> any inbound traffic that gets dropped by the firewall rules gets counted
> even if it is dropped by later rules.  It also seems like the outbound
> rule needs to be before any allow rules since an allow rule would skip
> the remaining rules and would not count that traffic.  Unfortunately the
> ipfw documentation doesn't really describe the interaction between
> dummynet, NAT, and other firewall rules.
> 
> Unfortunately this is a live system, so it is difficult to do controlled
> experiments and look at the ipfw counters to see where things might be
> going into the weeds ...
> 
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