These methods (disregarding the third) seem to be frowned upon, I didn't say these were the right thing to do I'm merely showing things you CAN do and things that are POSSIBLE.
Method 1: DDoS Attack
This method is fairly simple, first you must acquire the person's IP address, then you will continue to use a "booter" which is a program designed to instruct websites to direct their bandwidth to the person's internet router, slowing it down and eventually crashing it, I am not allowed to tell you what programs due to legalities.
After you have acquired said griefer's IP address you will continue to DDoS them using the program(s) previously stated, this will not only disconnect them from the server but from the internet itself as their router will have crashed, with the time they are offline you will be able to ban them from their IP address AND they will probably never attempty to come back.
Method 2: IP Banning
This method is not illegal in anyway, it will just stop people from entering the server with that ip address however, if this said griefer was using something called a proxy, this would not work because a proxy hides their IP address picture it like this;
GRIEFER ---> PROXY SERVER ---> MINECRAFT SERVER
So you would only get the proxy server's IP address, not the griefer themself, so they could switch their proxy or just disconnect entirely and still be able to join the server and continue to grief.
Method 3: Virus
This method involves you having to have a bit of social engineering, pretend as though you don't know anything about their griefing, this way they will not suspect anything suspicious, try to get their email, skype or any other form of communication where you can send files, once you have this you must send them an infected file, this file is called a RemoteAdministrationTool or RAT for short, this RAT will give you full control of their computer, allowing you to stop them in any way possible from getting onto your server/website.
Method 4: Java driveby
This is the same as method 3 but requires no filesharing whatsoever, this method may be a little more complex though.
You will still have to create an infected file however you will bind this file with a java applet onto a webpage, just say that it's a game you have created or something like that, this java applet will ask if they want to run java, but most games require java so they probably wont suspect anything, but what this will then do is download the file without them knowing onto their system, and then you have full control of the computer.
The tutorials involving viruses are not more in depth because of legal reasons and I will not be held responsible for more information, try Google.
Last edited by ImJak on Mon Apr 02, 2012 3:13 am; edited 1 time in total