Port scanning

Port scanning (also written as portscanning) is “a technique used by computer hackers by which an individual sends requests via a worm or other program to various networked computer ports in an effort to ascertain whether particular machines have vulnerabilities that would leave them susceptible to external intrusion.”

“Often used as an initial step in launching an attack on another computer or transmitting a virus, port scanning is a relatively unsophisticated, but highly effective, reconnaissance method, likened. . . as the electronic equivalent of ‘rattling doorknobs’ to see if easy access can be gained to a room.”