Re: DOS by Flooding a Network

From: Vitaly Osipov (wittat_private)
Date: Tue Jun 18 2002 - 05:13:17 PDT

  • Next message: Richard Ginski: "Re: DOS by Flooding a Network"

    >
    > Finally I would highly reccomend adding a stateful
    > packet filter between your ISP and your network, take
    > a look at netfilter.org, so you don't "have to weather
    > the storm" or whatever else your ISP has in store for
    > you. This will allow you to have a much tighter
    > control over the traffic entering your network as well
    > as traffic orininating from your network.
    
    As far as I understand, the problem is that their network becomes
    inaccessible during flood period. In this case any filtering on the client
    side (on their end of ISP connection) will not help much - flood traffic has
    to be filtered on fat provider's pipes, not after it filled up a thin client
    link.
    
    Regards,
    Vitaly.
    
    >
    > Hope this helps,
    > Guhan
    >
    > --- Richard Ginski <rginskiat_private> wrote:
    > > This past weekend, we experienced the periodic
    > > flooding of our network.
    > > The flooding caused our network to be inaccessible.
    > > The traffic has
    > > mainly been ICMP: large quantities of large spoofed
    > > packets...similar to
    > > "ping-of-death. Appropriate patching has been
    > > applied so the actual
    > > attach does not shut anything down. However, it does
    > > succeed in flooding
    > > of our network rendering it inaccessible.
    > >
    > > We are trying to figure out a way, if any, to
    > > mitigate this attack from
    > > flooding our network in the future. We tried to
    > > coordinate with our ISP
    > > upstream but they say they can't do anything....and
    > > we feel sending
    > > resets on our end would be useless and ineffective.
    > > We are trying to
    > > figure out a way to eliminate the "choke point" or
    > > "bottle neck" when
    > > the attacks occur. I feel we should be able to do
    > > something better than
    > > just "weathering the storm".
    > >
    > >
    > > Any suggestions?
    > >
    > > TIA
    > >
    > >
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