Curious: syncookies ready for distributed syn flooding?

From: Xuan Baldauf (xuan--lkml@baldauf.org)
Date: Sat Jun 10 2000 - 15:01:23 EDT

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    Hi,

    local german press tries to create a "cracker hype", because it was
    discovered that there were some trojans successfully out there (guess
    for which OS. ;o)). Some months ago, I read about "DDoS", syn flooding
    from different, probably spoofed, source addresses. I also read that
    it would be relatively easy to get rid of the problem by letting a
    firewall blindly accept incoming tcp connections and then forward the
    initial request after the originating host approved the connection.

    Now the question: Are syncookies exactly that without need for an
    extra firewall? Are they only destination-port and not
    source-ip-address specific? As a conclusion, will linux server stay
    alive when others starve due to too high load, therefore beeing
    resistant against those attacks?

    Xuân. :o)

    P.S.: I know, if the tcp connection is open, it is open, and if a
    server is waiting for request data which does not come for a long
    time, it's the server that has to close the dormant connection.

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