Neo Trace 3.25 is a free tool that can be used to trace a nick to their Internet Service Provider (ISP). This is useful if you are getting nuked or port scanned by a specific IP address, over and over. You can get information about their ISP, and usually will find an abuse email address. Then you can report them to their ISP if you feel the need. In some cases you will find that the account has actually been "hacked" and the hacker is using this address to "bounce" the attack. But in most cases the ISP Administrator should be glad to get the information.
A firewall is another good tool to have. You can get information on the value af a firewall, and download Zone Alarm's free firewall, from the link in the Site Menu, Firewalls. Also, you should look at the link DOS. There are a few old tools built right into Windows that can help you out too.
Anyway, since Neo Trace Express is freeware, I have it here as a download.
Download Neo Trace Express 3.25