[Dudelive]

There are many ways for that exact thing to happen. The most likely is you accidently downloaded something that had it inside. Warez sites are very famous for these things happening when downloading compressed files. The other way involves port scanners which act as tattle tales reporting back to the owner letting the owner know it found a certain type of port number at a specified location to be open.

There are several methods in which you can use to secure your system.
The first thing you need is a firewall that will report what is going OUT from your computer while at the same time letting you know what is trying to come in. The methods that work for me may not work for you, depemnding on your setup.

Thanks
Dudelive