Port Scanning

Keywords: networking, reconnaissance, tcp, icmp, udp, syn, ack, fin, xmas, null, ip, scanning, idlescan, ftp, port scanning

Port Scanning is the process of identifying listening ports on a target system. A Port Scanner is a tool used to identify such ports. Port Scanning reveals several attributes about the target system like running services, operating system, and running applications. Although all 65,535 can be scanned, it is often more time efficient to concentrate on a subset of entire port range which includes particularly interesting services such as http and ftp servers, remote shell ports, and others. Over the time a large number of port scanning approaches was developed ranging from classic TCP connect approach to more stealthy SYN, ACK and many others. Such approaches are covered below: