From owner-freebsd-net  Tue May  1 15: 1: 4 2001
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From: Darren Reed <darrenr@reed.wattle.id.au>
Message-Id: <200105012200.IAA22724@avalon.reed.wattle.id.au>
Subject: Re: (KAME-snap 4587) The future of ALTQ, IPsec & IPFILTER playing  together ...
In-Reply-To: <3AEF0A8D.83847A19@aurora.regenstrief.org> from Gunther Schadow at "May 1, 1 07:12:13 pm"
To: gunther@aurora.regenstrief.org (Gunther Schadow)
Date: Wed, 2 May 2001 08:00:40 +1000 (EST)
Cc: snap-users@kame.net, freebsd-net@freebsd.org,
	ipfilter@coombs.anu.edu.au, altq@csl.sony.co.jp
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In some email I received from Gunther Schadow, sie wrote:
> Gunther Schadow wrote:
> [snip]
> 
> .... to make things even more complicated, we also have the 
> berkeley packet filter (BPF) mechanism. Heck! How could
> so many things evolve that all do essentially the same 
> thing? The interesting thing about the BPF mechanism is
> that it is very generic. Filter rules are instructions
> of a virtual von-Neumann-machine (reminds me of 6502 
> assembler :-). Tcpdump uses BPF, at least on FreeBSD.
> But I think BPF is available on all 4.4 BSD derivatives.
> 
> where does this fit in the crowd?

BPF uses a byte-code language, like Java, to tell the
matching routine what bits to compare and return a "true or
false".  i.e. you need to build things around it if you want
to use it for packet matching, etc.


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