DDoS attacks

David Harmelin david.harmelin at dante.org.uk
Thu Jul 12 16:47:00 UTC 2001

At 08:45 AM 7/12/01 -0700, Roeland Meyer wrote:

>This is the main point, a script-kiddie hunt, with prosecution, is the ONLY
>real deterrent. Throw some of them in hotel greybar and remove them from
>computing, for life, and we may see some of this turn around.
>If a lady wears skimpy clothing, does she deserve to get raped? Obviously,
>not. If a computer has skimpy protection, does it deserve to be turned into
>a zombie? Simply because you forget to lock your car one night (whilst in
>your driveway), do you deserve to have it stolen? If you leave a $100 on
>your kitchen table, in your unlocked house, whilst you are working in your
>garage, do I have the right to sneak in the back door and take it while
>avoiding prosecution, on the grounds that you were careless? WRT EFFnet,
>does a prostitute deserve to be raped?

By the way, for those who care, there are relatively easy ways to fight DoS attacks:
* use netflow and a bunch of scripts to detect them automatically
* use BGP to block them on all your border routers instantly, based on destination
* use BGP and Unicast RPF to block them on all your border routers instantly, based on source, if you really need to

With a combination of all that, you can automatically block any major attack at your border. 

Is it scalable? Yes.

What about false alarms? We have implemented the detection bit. 
With a bit of tuning, we get 0.1% of false alarms and yet catch an average of 15 attacks per day, above 500 pkts/s (up to 10000s pkts/s).
I wouldnt be surprised if Tier1 networks would catch much more attacks than that, with the same tool.

My point: block automatically 99% of the DoS attacks at the top 10 transit providers level, and we may see DoS attacks be a thing of the past.
"Kiddies only do it because they can".


             * *         David Harmelin  	Network Engineer
           *     *				DANCERT Representative
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