if bpf fd's select()able?
roam at ringlet.net
Mon Sep 8 00:05:03 PDT 2003
On Sun, Sep 07, 2003 at 04:04:49PM -0700, Lev Walkin wrote:
> Dmitry Morozovsky wrote:
> >Dear colleagues,
> >[all below is for 4-STABLE]
> >I'm trying to write effective arp scanner for multi-interface router (esp.
> >multi-vlan); I plan to use multiple bpf devices attached to different
> >interfaces emitting ARP requests and filters listening to ARP replies; the
> >natural way to multiplex them for me is select().
> >However, my tests show that select()ing bpf fd does not lead to trigger
> >available to bpf filter; the process hangs in select state while parallel
> >tcpdump process shows packets desired *and* is in bpf state.
> >Am I missing something "base"? References (surely, I'd already read
> >manpages for bpf, pcap and related -- but did I still missed something
> >serious?) would be greatly appreciated.
> Yes, you're missing the interactive mode.
> Refer to BIOCIMMEDIATE in the bpf(4) manual page.
Also, I believe that for a month or so bpf devices have been able to
issue kqueue notifications, too, so - at least for FreeBSD - the "most
natural" way might now be kqueue() and not select() :)
Peter Pentchev roam at ringlet.net roam at sbnd.net roam at FreeBSD.org
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