What are the limitations of using getenv() and $_SERVER['REMOTE_ADDR'] to retrieve the IP address in PHP?

The limitations of using getenv() and $_SERVER['REMOTE_ADDR'] to retrieve the IP address in PHP are that they can be easily spoofed or manipulated by users. To ensure the accuracy and security of retrieving the IP address, it is recommended to use a combination of $_SERVER['HTTP_X_FORWARDED_FOR'] and $_SERVER['REMOTE_ADDR'] to validate and sanitize the IP address. 

// Get the client's IP address using a combination of $_SERVER['HTTP_X_FORWARDED_FOR'] and $_SERVER['REMOTE_ADDR']
$client_ip = $_SERVER['HTTP_X_FORWARDED_FOR'] ?? $_SERVER['REMOTE_ADDR'];

// Validate and sanitize the IP address
$client_ip = filter_var($client_ip, FILTER_VALIDATE_IP);

// Output the client's IP address
echo "Client's IP address: " . $client_ip;

Keywords

getenv $_SERVER REMOTE_ADDR limitations IP address

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