Php queries the local idle Port

Php queries the local idle Port php

I want to use php to write a file and return the local idle Port. how can this problem be achieved?

Reply to discussion (solution)

Netstat-

Netstat-
I want to write it on the php file, not just a command line.

What is the purpose of writing in php? How can php run on the server return the local port?

What is the purpose of writing in php? How can php run on the server return the local port?
A Cainiao. That is to say, it can be queried only in shell command lines?

Fsockopen: Try one port at a time.

Fsockopen: Try one port at a time.
Perfect. I just made it and I saw your answer. thank you!
The same idea!

Fsockopen: Try one port at a time.
Perfect. I just made it and I saw your answer. thank you!
The same idea! That is, the efficiency is a little low.