Or try
Sam Spade The owner has some interesting perspectives on computer security, or rather the lack of it no matter how hard you may try.
Enter the offending IP Adress number into the 'IP Whois' field and get the name and details of the offending computer. It may be spoofed though, and the owner will be unaware that they are hosting a parasite.
Monitoring probe attempts can be interesting, but Firewalls tell you too much and its not a good idea to ping the IPs of the sources. That tells them you're there and you've done the job for them by compromising your own invisibility - if you have any...
Check how tight your firewall is at Steve Gibson's
Shields Up free service. Be prepared for some surprises. After using his site my own PC is so tight it doesn't even know it exists itself, never mind anyone else.
But that doesn't guarantee safety. As long as you're on the internet someone, somewhere will get into your computer and screw it up.