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Re: /dev/tap and tcpdump don't go together very well?

Rhialto <> writes:

> On Sun 08 Apr 2007 at 16:21:48 +0200, Rhialto wrote:
>> BPF sees packets that come in from the wire and optionally (default
>> on; BIOCSSEESENT; apparently undocumented) the packets that the host
>> sends to the wire.
> This seems to be documented now in bpf(4).

This flag applies to packets injected via BPF, or is it also about bpf
seeing normal outgoing packets?  The man page (5-stable) is not really

>> Packets injected into BPF are sent to the wire only, not to the host.
> FreeBSD now apparently has an ioctl for this:
>      BIOCFEEDBACK    (u_int) Set packet feedback mode.  This allows injected
>                      packets to be fed back as input to the interface when
>                      output via the interface is successful.  When BPF_D_INOUT
>                      direction is set, injected outgoing packet is not
>                      returned by BPF to avoid duplication. This flag is ini-
>                      tialized to zero by default.

Is this separate from the bpf-ought-to-work-on-tap notion, and about how
writes to bpf can be made to interoperate with the local host?  If so,
do we need to port BIOCFEEDBACK to NetBSD's bpf implementation?

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