How Can I Control Session Timeouts in PHP?

Controlling Session Timeouts in PHP

When working with PHP, you may encounter the need to adjust the default session timeout settings. While php.ini modifications offer a solution, limited access to this file may prompt you to seek alternative methods.

Strict Session Timeouts

To enforce a strict upper bound on session inactivity, we can implement custom logic that stores this bound within the session data:

session_start();

$now = time();
if (isset($_SESSION['discard_after']) && $now > $_SESSION['discard_after']) {
    // Session has expired, destroy and start a new one
    session_unset();
    session_destroy();
    session_start();
}

// Set expiration time for both new and existing sessions
$_SESSION['discard_after'] = $now + 3600;

Relaxed Session Timeouts

If imposing a strict limit is unnecessary, you can rely on specific PHP configuration parameters to establish a lower bound:

// Server retains session data for at least 1 hour
ini_set('session.gc_maxlifetime', 3600);

// Clients retain session ID for exactly 1 hour
session_set_cookie_params(3600);

session_start();

This approach instructs the server to store session data for a minimum of one hour and clients to discard their session ID after the same duration.

Considerations

When imposing session timeouts, it's crucial to address both client-side and server-side settings. For maximum control and predictability, combine a strict upper bound with session.gc_maxlifetime's lower bound. However, be aware that session ID preservation may warrant attention, especially if its value is sensitive.

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