[URGENT!] Server being crashed with Cain!

http://www.oxid.it/cain.html

I know from my "spy", that my server is being crashed with that program. Please, tell me if it's possible, and if yes, how to protect (and counter-strike, cuz the other guy has server too)

CB 820
Windows 7 x64 Ultimate SP1
java version "1.6.0_24"
Java(TM) SE Runtime Environment (build 1.6.0_24-b07)
Java HotSpot(TM) 64-Bit Server VM (build 19.1-b02, mixed mode)

I don't really believe, that crashing a MC server is possible like that, but after my 2 weeks of surveillance and NO success (link to my old thread) i'm ready to try anything

 

http://en.wikipedia.org/wiki/Null_route

Perform a null route on the users IP address. It should have your box completely ignore anything coming from him.
As for a return attack, you could probably use the same thing on him. I wouldn't recommend it though, because an attack on a server is technically illegal. You could also go on and grief. Again, not recommending it. And please, don't DDOS him. I'm highly against networking warfare.

 

If i find a way to defend, i won't counterattack. How to acquire his IP? The server is on a dedicated server, but he's crashing from his home pc.

 

Edit: Guide to null route:

http://www.cyberciti.biz/tips/how-do-i-drop-or-block-attackers-ip-with-null-routes.html

As for getting his IP address, if you know his username it will say his IP right next to it in the server.log.

 

All clear, he's blocked. If there's another attacker and i don't know who he is, how can i acquire his IP? For future purposes.

 

'netstat' in command line. It will bring up all current connections to the computer. You just need to figure out which one they are.