Port Scanner

In hacker reconnaissance, a port scan attempts to connect to all 65536 ports on a machine in order to see if anybody is listening on those ports. Ports scans are not illegal in many places, in part because they don´t actually compromise the system, in part because they can easily be spoofed, so it is hard to prove guilt, and in part because virtually any machine on the Internet can be induced to scan another machine. Many people think that port scanning is an overt hostile act and should be made illegal. An attacker will often sweep thousands (or millions) of machines rather than a single machine looking for any system that might be vulnerable. Port scans are always automated through tools called Port Scanners.