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This article uses easy-to-understand examples to introduce how to check the port number of the CVM. The content is very detailed. Interested friends can use it for reference. I hope it will be helpful to you.

To view the CVM port, you need to log in to the cloud account and find your server in the console. You can view or reset the port in the security group configuration.

1. Use netstat to view port conditions

In the process of using Linux, if you need to know which ports are open in the current system, and the associated processes and users of these ports, you can query them through the netstat command. The parameters of the netstat command are described as follows:

-t: indicates that the TCP port is displayed

-u: indicates that the UDP port is displayed

-l: only monitor sockets are displayed

-p: displays the process identifier and program name, and each socket / port belongs to a program.

-n: show IP without DNS polling (operation can be accelerated)

two。 Common netstat command combinations

Netstat-na this command displays all active network connections. At the same time, you can also use grep, wc, sort and other linux commands to analyze the connections in the system, check the number of connections, and determine whether the CVM has been attacked.

Netstat-an | grep: 80 | sort displays all 80-port network connections and sorts them. Port 80 here is a http port, so it can be used to monitor web services. If you see a large number of connections to the same IP, it is determined that there is a suspected single point of traffic attack on the IP.

Netstat-n-p | grep SYN_REC | wc-l counts the number of active SYNC_REC connections on the current server. Normally, this value is very small (less than 5). When there is a ddos attack, this value can be very high. However, some servers with high concurrency do have a high value, so a high value does not necessarily mean that it is the result of an attack.

This is the end of how to view the port number of the CVM. I hope the above content can be helpful to you and learn more. If you think the article is good, you can share it for more people to see.

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