Hi,
Well, I guess its time for you to learn about tools like 'wireshark'.
Have it filtering all packets that look like a ddos-packet. This means of course: you (as a person) should know everything about what dddos really is.
Bad news: the technical subject is huge ...
A better solution is: do nothing, sit it out. You have an OVH server (right ?) so their ddos protection will somewhat protect your server.
Edit : regarde aussi ici :
http://forum.ovh.com/showthread.php?...gation-OVH-pro