Did you ever wondered what cloudflare  is? It is basically an protection against Distributed Denial of Service attack , where your server is attacked via a massive flood of incoming traffic, trying to overload your server.
But there is an easy and cost saving way to protect your server – of course if you are running it on Linux. Simply check DDoS Deflate from github . After installing, the script checks frequently your incoming traffic. Once an IP address generates a critial mass of incoming traffic attempts, the IP address is blocked.
Just consider that you might want to whitelist certain IP addresses or domains – for that check the manual.
After installing DDoS Deflate  on jvr.at, the impact can be seen on the statistics of the website. No more peak pointing out a DoS attack since beginning of December.