Yesterday an interesting HTTP DoS tool has been released. The tool performs a Denial of Service attack on Apache (and some other, see below) servers by exhausting available connections. While there are a lot of DoS tools available today, this one is particularly interesting because it holds the connection open while sending incomplete HTTP requests to the server.
In this case, the server will open the connection and wait for the complete header to be received. However, the client (the DoS tool) will not send it and will instead keep sending bogus header lines which will keep the connection allocated.

At the moment I'm not sure what can be done in Apache's configuration to prevent this attack

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