These days, home PCs are a desirable target for attackers. Most
of these systems run Microsoft Windows and often are not
properly patched or secured behind a firewall, leaving them
vulnerable to attack. In addition to these direct attacks,
indirect attacks against programs the victim uses are steadily
increasing. Examples of these indirect attacks include malicious
HTML-files that exploit vulnerabilities in Microsoft's Internet
Explorer or attacks using malware in Peer-to-Peer networks.
Especially machines with broadband connection that are always on
are a valuable target for attackers. As broadband connections
increase, so to do the number of potential victims of attacks.
Crackers benefit from this situation and use it for their own
advantage. With automated techniques they scan specific network
ranges of the Internet searching for vulnerable systems with
known weaknesses. Attackers often target Class B networks ( /16
in CIDR notation) or smaller net-ranges. Once these attackers
have compromised a machine, t