The purpose of port scanning is to scan a series of TCP ports connected by a large range of hosts and judge which services the host has opened. These open ports usually correspond to certain services. Through these open ports, we can learn about the services run by the host, and then we can further sort out and analyze the possible vulnerabilities of these services, and then take targeted attacks.

Port scanning means that some people with ulterior motives send a set of port scanning messages in an attempt to invade a computer and find out the types of computer network services it provides (these network services are all related to port numbers). Port scanning is the favorite way of computer decryption experts. Through it, the attacker can know where to find the attack weakness. Essentially, port scanning involves sending messages to each port, one at a time. The type of response received indicates whether the port is in use and can be used to detect vulnerabilities.

Port scanning principle

Port scanning, as its name implies, is to scan a section of ports or specify ports one by one. Through the scanning results, we can know what services are provided on a computer, and then we can attack through the known vulnerabilities of these services. The principle is that when the host sends a request to establish a connection to the port of a remote server, if the other party has this service, it will reply. If the other party does not install this service, even if you send a request to the corresponding port, the other party still does not reply. Using this principle.