(1). REMOTE_ADDR: The IP address of the user's computer that is browsing the current page
(2). Http_x_forwarded_for: A gateway to the user's computer that browses the current page
(3). HTTP_CLIENT_IP: IP for Client
Use $_server["REMOTE_ADDR" in PHP to obtain the IP address of the client, but if the client is accessed using a proxy server, it is the IP address of the proxy server, not the real client IP address. To get the real IP address of the client through the proxy server, it is necessary to use $_server["http_x_forwarded_for" to read.
However, it is important to note that not every proxy server can use $_server["http_x_forwarded_for" to read the client's real IP, some of which are still read by this method is the proxy server IP.
It is also important to note that if the client is not accessed through a proxy server, then the value taken with $_server["http_x_forwarded_for" will be empty.
The above describes the iphone caller ID attribution to the software PHP to get the real IP address of the remote client, including the iphone caller ID to display the content of the software, I hope to be interested in PHP tutorial friends helpful.