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Date:      Sat, 17 Apr 1999 18:18:27 +0200 (MET DST)
From:      Luigi Rizzo <luigi@labinfo.iet.unipi.it>
To:        svetzal@cujo2.icom.ca (Steven Vetzal)
Cc:        freebsd-net@FreeBSD.ORG
Subject:   Re: Dummynet & Bridging
Message-ID:  <199904171618.SAA16929@labinfo.iet.unipi.it>
In-Reply-To: <000601be88fd$0ed07b00$7ffea8c0@blazer.pr1.on.wave.home.com> from "Steven Vetzal" at Apr 17, 99 02:06:26 pm

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> Greetings,
> 
> I've been having some fun trying to get dummynet working on a bridging
> configuration, and was wondering if what I'm trying to do is implemented.
> I'm doing this on 3.1-RELEASE

i am assuming that you did it on 3.1 stable because 3.1-R was missing
some pieces in the device driver(s) etc.

> 00600  1211   72660 allow ip from 192.168.254.1 to 192.168.254.132 out xmit
> mx0
> 00620  1220   73200 allow ip from 192.168.254.132 to 192.168.254.1 out xmit
> xl0
> 
> Now that I know traffic is working great through the rules, I try adding a
> "pipe" rule higher up the chain to redirect the packets:
> 
> ipfw add 500 pipe 1 ip from 192.168.254.1 to 192.168.254.132 out via mx0
> 
> The .132 host continues to ping, and tcpdump shows the packet hitting his
> side of the bridge, hitting the other side of the bridge, the .1 host
> response hitting the other side of the bridge, but the response doesn't get
> carried through the bridge back to the source host.

try 

sysctl -w net.inet.ip.firewall.one_pass=1

so that the pkt is not reinjected in the firewall after the pipe
(should not happen with bridging, but still...)
This said, there might be some bug somewhere, i could not test this
code (interaction of bridging and dummynet)
on the 3.x branch, only on 2.2.x.
If you can, i suggest to put some diagnostic msg near the beginning of
bdg_forward, in the place where a dummynet pkt is recognised, to
understand what happens to the pkt.

> Now dummynet(4) says that the ipfw filter is invoked only once on a bridge,
> on the input path. But my attempt at:
> 
> ipfw add 500 pipe 1 ip from 192.168.254.1 to 192.168.254.132 in via xl0
> 
> and all variations I can think of show no traffic flowing through the rule.
> 
> Now I'm sure I've got this all confused, but can't find documentation
> anywhere on how this stuff works... And I'm not even sure it's supposed to.
> The reason I'm not sure it's supposed to work is because if I set up the
> following rules:
> 
> 00500    60    3600 pipe 1 ip from 192.168.254.8 to 192.168.254.132 out
> 00510    16     960 pipe 2 ip from 192.168.254.132 to 192.168.254.8 in
> 
> I can ping the _bridge host_ and receive a response and the two rule
> counters increment as I figure they would. However, bridging has to be
> working to some degree because the interface I ping is not the one connected
> to this host! (the interfaced attached to my test host is unnumbered)

well, that's only a thing done in the reception side.

	cheers
	luigi



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