What best practices should be followed when working with server variables like $_SERVER['REMOTE_ADDR'] in PHP scripts?

When working with server variables like $_SERVER['REMOTE_ADDR'] in PHP scripts, it is important to validate and sanitize the input to prevent security vulnerabilities such as injection attacks. One best practice is to use filter_var() function with FILTER_VALIDATE_IP filter to validate the IP address. Additionally, it is recommended to set up a whitelist of trusted IP addresses if necessary. 

// Validate and sanitize the REMOTE_ADDR server variable
$remote_addr = filter_var($_SERVER['REMOTE_ADDR'], FILTER_VALIDATE_IP);

// Check if the IP address is valid
if ($remote_addr) {
    // Proceed with the script
    echo "Valid IP address: " . $remote_addr;
} else {
    // Handle invalid IP address
    echo "Invalid IP address";
}

Keywords

PHP $_SERVER REMOTE_ADDR security validation

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