How to limit the number of failed login attempts in PHP?

@mallory_cormier 

To limit the number of failed login attempts in PHP, you can follow the below steps:

1. Define a maximum number of allowed login attempts: This will be the number of times a user is allowed to attempt to login before they are locked out.
2. Store the number of failed login attempts: Each time a login attempt is made, you should increment a counter that stores the number of failed login attempts for that user.
3. Check the number of failed login attempts: Before allowing a user to attempt to log in, you should check their failed login attempt counter. If the number of failed login attempts is greater than or equal to the maximum number of allowed attempts, you should prevent the user from attempting to log in.
4. Implement a lockout period: If a user exceeds the maximum number of allowed login attempts, you can lock them out for a specified period of time. During this time, the user should not be able to attempt to log in. You can store the lockout start time and duration in a database or a cache.
5. Reset the failed login attempts counter: After a successful login, you should reset the failed login attempt counter for that user.

Here is a sample PHP code to implement the above steps:

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// Define maximum number of allowed login attempts
$max_login_attempts = 5;

// Get the number of failed login attempts for the user
$failed_login_attempts = get_failed_login_attempts($username);

// Check if the user has exceeded the maximum number of allowed login attempts
if ($failed_login_attempts >= $max_login_attempts) {
    // Lock out the user for a specified period of time
    $lockout_duration = 10; // in minutes
    set_lockout($username, $lockout_duration);
    die("You have exceeded the maximum number of allowed login attempts. Please try again after $lockout_duration minutes.");
}

// Attempt to validate the user's credentials
if (validate_credentials($username, $password)) {
    // Reset the failed login attempt counter for the user
    reset_failed_login_attempts($username);
    // Log the user in
    login($username);
} else {
    // Increment the failed login attempt counter for the user
    increment_failed_login_attempts($username);
    die("Invalid username or password. Please try again.");
}

Note that in the above code, get_failed_login_attempts(), set_lockout(), reset_failed_login_attempts(), validate_credentials(), and login() are custom functions that you will need to implement according to your specific requirements.