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    SubjectRe: No more DoS
       Date: 	Fri, 22 Dec 2000 13:24:44 +1100 (CST)
    From: Mike OConnor <>

    I would like to point who ever is in charge of the TCP stack for
    the linux kernel at a site which claims to have a method of
    eliminate denial of service (DoS) attacks

    With my limited unstanding of TCP and DoS attacks this would seem
    to be the answer, instead of a work around.

    These people claim that no connection state needs to be saved for the
    beginning of the negotiation, and I claim this is unworkable because
    it ignores TCP timestamps entirely.

    Furthermore, it also cannot work because it makes retransmissions
    of the SYN/ACK very non-workable. I suppose his TCP stack just hacks
    around this by just waiting for the original client SYN to get
    retransmitted or something like this. I question whether that can
    even work reliably.

    I think not holding onto any state for an incoming SYN is nothing but
    a dream in any serious modern TCP implementation. It can be reduced,
    but not eliminated. The former is what most modern stacks have done
    to fight these problems.

    David S. Miller
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