How to get the real IP address of the remote client in iPhone caller ID software in PHP

(1).REMOTE_ADDR: The IP address of the user's computer browsing the current page
(2).HTTP_X_FORWARDED_FOR: The gateway of the user's computer browsing the current page
(3).HTTP_CLIENT_IP: The client's IP
Use $_SERVER["REMOTE_ADDR" in PHP "] to obtain the client's IP address, but if the client uses a proxy server to access, what is obtained is the IP address of the proxy server, not the real client IP address. To obtain the client's real IP address through a proxy server, use $_SERVER["HTTP_X_FORWARDED_FOR"] to read it.
But please note that not every proxy server can use $_SERVER["HTTP_X_FORWARDED_FOR"] to read the real IP of the client. Some of the IPs read by this method are still the IP of the proxy server.
Another thing to note is that if the client does not access through a proxy server, the value obtained with $_SERVER["HTTP_X_FORWARDED_FOR"] will be empty.

The above introduces the method of obtaining the real IP address of the remote client in the iPhone caller ID software PHP, including the content of the iPhone caller ID software. I hope it will be helpful to friends who are interested in PHP tutorials.