someone hacking my network

[halfdone]

Hi,

I have a computer that uses windows 2000, its updated, and there is F-Secure installed.
Iv started to have announcements that F-Secure has stopped a Nmap scan.
The computer is behind a old router and its the only computer behind that router.

Now I have started to understand how to use nmap, I started to wonder, how someone can come true my router and start nmap scan in my home network.

Well I dont like it and I want to stop getting those announcements. and the only way is to find out how "he" does it and sthen edit modems settings.

[Archangel-Amael]

While this doesn't have much to do with Back Track I will entertain the thread.
First and foremost just because you are being scanned does not mean you are being hacked as per your title.
There are probably millions of scans going on the internet at any one time. As such trying to figure out who or why it is being done would be a waste of your time.
Smarter things to do would be to update your OS to the latest patch level. Update your router if you can. Lock down/ remove all unneeded services and ports.
Be wary of where and how you surf and of course using industry best practices for passwords.
There are a million other things to do (the least of which would be to unplug from the internet) but this will get you started.