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    SubjectRe: ECN & cisco firewall
    On Fri, 8 Sep 2000, David S. Miller wrote:

    > The authors of rfc793 probably, in all honesty, really meant
    > "must be set to zero by current implementations".

    Thats often the problem when interpretations are possible: Different
    people see the meaning differently.

    > Even though they did not say this, several pages later they bestow
    > upon us the concept of being liberal in what one accepts. Perhaps
    > Cisco PIX firewall engineers missed this paragraph. :-) Also, there
    > is not one part of the packet parsing steps they describe which says
    > "if any reserved flag bits are non-zero, drop packet" or "reset" (the
    > sites which RST these ECN carrying packets are the ones which disturb
    > me the most, in the Cisco PIX case does the firewall send a reset
    > back?).

    In case i havent sayed this clearly enough: It seems after several
    tests: the PIX itself sent the RST (blocking the connection) instead of
    letting the SYN pass to the actual host (behind the firewall)

    > That's a really anal, zero purpose, check to put into a firewall.
    > I don't know of even any embedded printer stacks that puke when
    > the reserved flag bits are non-zero. The only things this protects
    > anyone from are extensions such as ECN :-)

    Yeah, but we will see what cisco has to say about that....

    LL&P Ulrich
    --
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