In PHP, you can obtain the IP addresses of both the client and the server using built-in functions. The client's IP address can be retrieved using $_SERVER['REMOTE_ADDR'], while the server's IP address can be obtained using $_SERVER['SERVER_ADDR']. These pieces of information are extremely useful for tracking user behavior and preventing malicious attacks.

There are several commonly used methods to obtain the client and server IP addresses in PHP:

1. Obtaining the Client IP Address

The following methods can be used to retrieve the client's IP address:

• $_SERVER['REMOTE_ADDR']: This method returns the IP address of the client who made the request by default.
• $_SERVER['HTTP_CLIENT_IP']: If the client is sending the request through a proxy server, this method can be used to obtain the client's real IP address.
• $_SERVER['HTTP_X_FORWARDED_FOR']: If the client is sending the request through multiple proxy servers, this method can be used to obtain the client's real IP address.

2. Obtaining the Server IP Address

The following method can be used to retrieve the server's IP address:

• $_SERVER['SERVER_ADDR']: This method returns the IP address of the server running the PHP script.

3. Using the gethostbyname() Function to Retrieve IP Addresses

The gethostbyname() function can be used to obtain the IP address corresponding to a hostname.

Here is an example code that demonstrates how to retrieve the client and server IP addresses:

<?php
// Retrieving the client IP address
$clientIP = $_SERVER['REMOTE_ADDR']; // By default, this method returns the IP address of the client who made the request.
$clientRealIP = $_SERVER['HTTP_CLIENT_IP']; // If the client is sending the request through a proxy server, this method returns the client's real IP address.
$clientForwardedFor = $_SERVER['HTTP_X_FORWARDED_FOR']; // If the client is sending the request through multiple proxy servers, this method returns the client's real IP address.

// Retrieving the server IP address
$serverIP = $_SERVER['SERVER_ADDR']; // This method returns the IP address of the server running the PHP script.

// Using the gethostbyname() function to retrieve IP addresses
$hostname = 'www.example.com'; // Replace with the hostname or domain name you want to query
$ipAddress = gethostbyname($hostname); // This method returns the IP address corresponding to the hostname.
?>

Please note that the values of the variables in the above code are read-only and cannot be directly modified. If you need to use the retrieved IP addresses for other purposes, such as logging or sending emails, please store them in appropriate variables for further processing.

Below is a simple overview of how to use PHP to retrieve the client and server IP addresses:

Below is a detailed explanation:

Retrieving the client IP:

// Storing the client IP address in a variable
$clientIP = $_SERVER['REMOTE_ADDR'];

Retrieving the server IP:

Method 1:

// Obtaining the server's hostname, then retrieving its IP address
$serverIP = gethostbyname(gethostname());

Method 2:

// Retrieving the server's IP address directly from the $_SERVER array
$serverIP = $_SERVER['SERVER_ADDR'];

Please note that gethostbyname(gethostname()) may not return the server's public IP address on all environments; it may return the default local IP address specified in the server configuration file.

Here is an integrated PHP code example:

    
    
    



    

        
Functionality
        
IP Address
    
    

        
Retrieving the client IP
        
<?php echo $_SERVER['REMOTE_ADDR']; ?>
    
    

        
Retrieving the server IP (via hostname)
        
<?php echo gethostbyname(gethostname()); ?>
    
    

        
Retrieving the server IP ($_SERVER)
        
<?php echo $_SERVER['SERVER_ADDR']; ?>
    

This code will generate a simple HTML document that displays the client and server IP addresses in a table when viewed in a browser. If you run this code in a local environment (e.g., XAMPP or MAMP), the server IP obtained will usually be the loopback address (127.0.0.1). On a deployed server, it will show the actual public IP address of the server.

That wraps up this article on retrieving client and server IP addresses in PHP. Feel free to leave a comment, follow us for more content, like this post, and thank you for reading!