tcpdump mailing list archives

Re: Scanning IP6 packets


From: Michael Richardson <mcr () sandelman ca>
Date: Thu, 14 Nov 2013 14:26:18 -0500


Darren Reed <darrenr () netbsd org> wrote:
    >> Or write your own filter expression that looks at the link-layer
    >header to detect IPv6 packets, skips past the IPv6 header (you won't be
    >able to handle extension headers, as that involves looping, and the
    >libpcap filter language doesn't support that), and then loads the
    >appropriate value from the TCP header based on that.
    >>
    >> There is no easy solution.

    > Something that I'm working on is a design & implementation of BPF (v2) that
    > incorporates instructions that are specifically designed to deal with
    > headers

That's cool...

    > that are chained together in this fashion. In its current form, BPF (v1) is
    > not that IPv6 friendly. Give me a week or two to back up a design with some
    > code that works (the parser and compiler bit are the tricky pieces.)

True. I assume you are adding kind of limited loop capability.  Could it be
unrolled to some depth to work with BPFv1?

--
]               Never tell me the odds!                 | ipv6 mesh networks [
]   Michael Richardson, Sandelman Software Works        | network architect  [
]     mcr () sandelman ca  http://www.sandelman.ca/        |   ruby on rails    [

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