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List:       wireshark-dev
Subject:    Re: [Wireshark-dev] Are Capture Filters Implemented in Software or the Network Card?
From:       Gene Cumm <gene.cumm () gmail ! com>
Date:       2021-11-22 2:36:03
Message-ID: CAD0RxentM46U=_zXQpDnH1sbsisXByo=cXnmAKZ-2+KhR2zP0A () mail ! gmail ! com
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On Sun, Nov 21, 2021, 2:07 PM Guy Harris <gharris@sonic.net> wrote:

> The filtering is *not* done in the network adapter (which isn't
> necessarily a card - it could be built into the computer); an adapter that
> does the filtering itself could probably be built, and libpcap could be
> modified to recognize cards that can do filtering and to tell the adapter's
> driver, rather than the kernel's packet capture mechanism, what the filter
> program is.  I don't know of any adapters of that sort, however, and
> libpcap currently has no code to do so.
>

I'd still consider LoMs "cards" in a loose sense but that's me.

FPGA-based network acquisition cards do implement filters in "hardware"
(not in the system CPU).  Napatech, Accolade, Silicom and Chelsio have
products.

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<div dir="auto"><div><br><br><div class="gmail_quote"><div dir="ltr" \
class="gmail_attr">On Sun, Nov 21, 2021, 2:07 PM Guy Harris &lt;<a \
href="mailto:gharris@sonic.net">gharris@sonic.net</a>&gt; wrote:</div><blockquote \
class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc \
solid;padding-left:1ex"> The filtering is *not* done in the network adapter (which \
isn&#39;t necessarily a card - it could be built into the computer); an adapter that \
does the filtering itself could probably be built, and libpcap could be modified to \
recognize cards that can do filtering and to tell the adapter&#39;s driver, rather \
than the kernel&#39;s packet capture mechanism, what the filter program is.   I \
don&#39;t know of any adapters of that sort, however, and libpcap currently has no \
code to do so.<br> </blockquote></div></div><div dir="auto"><br></div><div \
dir="auto">I&#39;d still consider LoMs &quot;cards&quot; in a loose sense but \
that&#39;s me.  </div><div dir="auto"><br></div><div dir="auto">FPGA-based network \
acquisition cards do implement filters in &quot;hardware&quot; (not in the system \
CPU).   Napatech, Accolade, Silicom and Chelsio have products.    </div></div>


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