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Comment on Understanding the recent DDoS attack against Read the Docsparent

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As you say, even at 90 seconds, it's clear to all involved parties that the customer is pwned or malicious.

It sure is --- but an ISP would want to observe the traffic themselves, and if it's a 90 second attack every so often, chances are they won't see it when they look. When it's volumetric reflection, you can probably tell them how to send a request and see the response, and maybe they'll contact the customer, but maybe they'll just sit on it. As a victim, the ROI for reporting just wasn't there.

I wasn't getting huge traffic flows, and I was mostly getting attacks against www, which wasn't my actual service, so making sure volumetric attacks below my interface rate were shrugged off and taking simple actions like dropping requests from http clients with user-agent Wordpress were good enough. If the volumetric attacks were much over 10G, my host would have null routed my servers, which is annoying but highly scalable --- many ISPs support a BGP blackhole community, so my host can add my attacked IP to that and their upstreams will drop inbound packets when they enter the ISPs network.

I can't find a reference now, but I've seen things that allowed for more specific blackholing, such as by source or destination port number or by protocol. If my host's ISPs are dropping all UDP and IP fragments to my IP under attack, I could keep serving my TCP traffic and ignore a huge DDoS. I wouldn't even be able to measure the size of the DDoS.

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