What are the drawbacks of relying solely on IP addresses for user identification in PHP applications?

Relying solely on IP addresses for user identification in PHP applications can be unreliable as IP addresses can change frequently, especially for users on mobile devices or using VPNs. This can lead to incorrect identification or authentication issues. To solve this problem, it is recommended to use additional methods of user identification, such as session tokens or cookies. 

// Example of using session tokens for user identification
session_start();

if(isset($_SESSION['user_id'])) {
    // User is authenticated
    $user_id = $_SESSION['user_id'];
} else {
    // Redirect to login page
    header("Location: login.php");
    exit();
}

Keywords

IP addresses user identification PHP applications security vulnerabilities session hijacking

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