What does port scanning mean?

Since the ports on your computer are where information is sent and received, port scanning is similar to knocking on the door to see if anyone is home. Now let’s take you through port scanning, hoping it will be helpful to you.

Port scanning

Port scanning is used to identify open ports and services available on network hosts The name of a technology that checks all ports on an IP address to see if they are open or closed.

Security technicians sometimes use it to audit computers for vulnerabilities, but hackers also use it to attack their victims. It is considered an open hacking technique where hackers perform port scanning techniques to find vulnerabilities within specific computer ports. To an intruder, these weaknesses represent opportunities for attack.

There are 65,535 ports in each IP address, and hackers may scan each port to find any unsecured ports.

How does port scanning work?

Port scanning is very simple: send a request to connect to the target computer, and then keep track of which ports appear to be open or which respond to the request.

There are three possible responses:

1. Open, Accept: The computer responds and asks if there is anything it can do for you. things.

2. Closed, not listening: The computer responds "This port is currently in use and unavailable at this time."

3. Filter, discard, block: The computer doesn't even bother to respond, it doesn't have time for pranks.

Types of port scans

Ping scan:

The simplest port Scanning technology used to scan entire network blocks or individual targets to identify which computers on the network are active. It sends an ICMP echo request to the target, and if the response is an ICMP reply, it means the target is active.

vanilla scan:

The most basic type of scan, the scanner will try to connect to all 65,535 ports. It is a full connection scan, which sends the SYN flag (requesting a connection), and after receiving the SYN-ACK (connection confirmation) response, sends back the ACK flag. Full connection scans are accurate but very easy to detect because the firewall always logs full connections.

SYN Scan: Also known as Half-Open Scan (TCP Half-Open)

This is a quick and sneaky scan that attempts to find potentially open scans on the target computer port. This scan is fast because it never completes the full TCP 3-way handshake. The scanner sends a SYN message and only records the SYN-ACK response. The scanner does not complete the connection by sending a final ACK: it leaves the target dangling.

strobe scan: A more focused scan that only looks for known developed services

UDP: The scanner looks for open UDP Port

FTP Bounce Scanning: The scanner masquerades the scan source through an FTP server, allowing packets to be bounced through the FTP server to masquerade the sender's location.

Stealth Scan: Used to collect information without being logged by the target system, the scanner prevents the scanned computer from logging port scan activity.

Summary: Port scanning is the first step in any vulnerability analysis or penetration testing; knowing which ports are open is the beginning of being able to actively communicate with the target. Port scanning itself does not constitute a crime. We can protect port scanning through the use of firewalls.

This article ends here. I hope it will be helpful to everyone's study. For more exciting content, you can pay attention to the relevant tutorial columns of the PHP Chinese website! ! !

The above is the detailed content of What does port scanning mean?. For more information, please follow other related articles on the PHP Chinese website!