Which network are you attached to ie which provider?
It is quite common feature of the real internet.
Most IP's block it before it gets to you.
Whats happening is some scally is going through a whole range of IP addresses using a robot hacker trying to find a machine with a security breach. After they find one something nasty can happen or its just a youngster having fun and learning about system security. Or they use your machine a jump station to try and hide what they are really up to.
I have known many hackers who have turn game keeper and the all earn 6 figure sums but now try and hack systems on request instead of on the fly.