Date: Tue, 1 Jun 2021 12:58:53 +0200 From: Martin Husemann <martin@NetBSD.org> To: freebsd-wireless@FreeBSD.org Subject: Re: monitor mode APs and bpf DLTs Message-ID: <20210601105853.GA7002@mail.duskware.de> In-Reply-To: <20210524121920.GA29192@mail.duskware.de> References: <20210524121920.GA29192@mail.duskware.de>
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On Mon, May 24, 2021 at 02:19:20PM +0200, Martin Husemann wrote: > Hey folks, > > I am slightly confused about the bpf details for wireless devices. ... and once you have seen it work, it all unriddles. So I made two errors: - I picked run(4) as a test example, but radiotap support (kinda obvious once you think of it) is device dependent - and the run driver does not support it. The device driver needs to set ic_th (the tap header and properly initialize the length field before finalizing attachment. - I was confused by the mumbling of tcpdump about monitor mode and somehow assumed different/more link layer types would be available in monitor mode (which IIUC [now] never is the case in FreeBSD) and then totaly confused radiotap bpf access with monitor mode VAPs, but of course they are orthogonal/independent. Sorry for the noise. Martin
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