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No matching port or service found.
Deep resolution: the logical meaning of the port in network communication
If the IP address is the Internet Building's door sign, Port is the door to the different rooms. In OSI The transmission layer of the model (TCP/UDP), with port numbers used to distinguish between different network applications that are operated on the same computer. Understanding the distribution patterns of common ports is the first step towards network management and safety protection.
Classification and distribution of port numbers
- Other Organiser Range from 0 to 1023. These ports are closely tied to core web services such as HTTP (80), HTTPS (443), SSH (22) and FTP (21). Usually only system-level processes can monitor these ports.
- Registered Ports: The range is 1024 to 49151. These ports are usually assigned to user processes or specific applications, such as MySQL (306) and Redis (6379)。
- Dynamic/private port (Dynamic Ports): The range ranges from 49152 to 65535. Usually, the operating system dynamically assigns the client to a temporary port at the time of the launch.
How can the actual problem be solved through port queries?
Scenario one: firewall rule configuration. When you deploy a new Web application (if used) Nginx) You need to know clearly the port at which it is listening and to open the corresponding traffic in the cloud server security group or the local firewall. This tool helps you to confirm the standard port of each service, avoiding being inaccessible due to a configuration error.
Scenario 2: Cybersecurity audit. When you find that the server has opened an unknown port, you can use this tool to query the common service associated with the port, which helps you quickly to determine whether there is unnecessary service exposure or potential malware listening.
Key protocol statement: TCP vs UDP
TCP (transmit control protocol): Reliable transmission for connections, applicable to web browsing (HTTP), mail sending (SMTP) Connect to the database to ensure that the data are complete.
UDP (user data reporting protocol): Unconnected unreliable transmissions, but fast, low cost, are suitable for domain name resolution (DNS), online video stream and real-time games.