I am currently using Ubuntu Desktop 11.04 and enabled the firewall using GUFW. I have also disabled all the unnecessary services. I am connected to the internet and would like to know details of any other systems trying to scan my system for any open ports or for any vulnerabilities. Is there any software which will log this into a file, which I can check?
Note: I am looking for an approach which can be followed by novice users of Ubuntu and not only by experts. GUI is preferred.