Date: Thu, 10 Mar 2016 14:33:21 -0800 (PST) From: Don Lewis <truckman@FreeBSD.org> To: julian@freebsd.org Cc: freebsd-ipfw@freebsd.org Subject: Re: ipwf dummynet vs. kernel NAT and firewall rules Message-ID: <201603102233.u2AMXLCx016193@gw.catspoiler.org> In-Reply-To: <56E1D923.6060405@freebsd.org>
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On 10 Mar, Julian Elischer wrote: > On 9/03/2016 9:32 AM, Don Lewis 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 ... > > ok so you need to do what I always tell people.. split your rules into > separate incoming and outgoing rule sets. > so your first rule should be: > skipto 10000 all from any to any in. > > > and have separate sets of rules for incoming and outgoing packets. I'm somewhat used to that. In a past life I wrote firewall rules for routers that have separate per-interface in and out rulesets. I do recall genrating them from from a script that kept the in and out rules for the desired flows in sync with each other. In this case, it would require a total rewrite from what I have now, which I'm not anxious to tackle at the moment.
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