If your strictly interested in defending your system, your best bet is to get a good firewall. A good firewall will automatically log the IP addresses of any attackers. Then you can do a whois lookup and find out who their ISP is and complain to them. Tiny personal firewall is one you can get for free. I haven't used it, but a lot of the more experienced members seem to like it. I use Norton Personal Firewall 2002, and I don't have any complaints. Sam Spade is a good tool you can download for free, and you can use it to do whois look ups. Try www.samspade.org What I don't recommend is that you try to go on the offense and hack the crackers. That can get you into serious trouble.