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First of all, let's open the command interface of the Linux to view the port, as shown in the figure (take the Ubuntu system as an example)

Then, in order to get higher permissions (view all ports), switch root login here

The first method is to use the lsof-I: Port number command line, taking 80 as an example, as shown in the figure:

If there is no output, the port number is not opened. In order to facilitate testing, I detect an open port number here, and the information shown in the figure will be output.

The second way is to use the netstat-aptn command line to check all open port numbers

The command shown in the figure is to view all the port numbers in the system that use the udp protocol

Then this command is to view the port number information on the system that uses the tcp protocol.

These are the details of how to check whether the designated port is open in linux. For more information, please follow other related articles!

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