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[altq 823] Re: The future of ALTQ, IPsec & IPFILTER playing together ...
In some email I received from Gunther Schadow, sie wrote:
> Gunther Schadow wrote:
> .... 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.