Date: Sat, 16 Mar 2019 23:17:21 -0500 From: Kyle Evans <kevans@freebsd.org> To: freebsd-net <freebsd-net@freebsd.org> Subject: if_bridge(4)/bpf on incoming packets Message-ID: <CACNAnaEZtJdOkuq3i9grV0VBqGaemLhq_UR7a4%2Buc1eDhErk=Q@mail.gmail.com>
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Hi, Given a setup like: ifconfig bridge0 create ifconfig bridge0 addm em0 addm wlan0 up Packets coming in on em0 that get routed to wlan0 by the bridge will not be passed over to wlan0's bpf(4). I have an open review [0] that proposes changing this so that if we're passing traffic over a bridge, it gets exposed to the destination interface's bpf interface assuming it's not the interface that just injected it into the bridge. I don't know the history here, though- is there any particular reason bridge doesn't/shouldn't do this now, or is it just that it's not useful by conventional (read: almost all) usage of a bridge? My motivation is that in a particular testing setup I am playing with, either em0 or bridge0 get a DHCP address and wlan0 (actually not wlan0 in my testing setup, but keeping with the above example for convenience) also needs to pull a DHCP address from the em0 side of the bridge for... reasons. =) I also anticipate needing to actually monitor traffic received from the bridge by wlan0 along with traffic received on wlan0, rather than monitoring the bridge, so the above change makes this most convenient. Thanks, Kyle Evans [0] https://reviews.freebsd.org/D19586
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