What are the potential risks of relying solely on Captchas for preventing spam in PHP forums?

Relying solely on Captchas for preventing spam in PHP forums can be risky because Captchas can be easily bypassed by automated bots or sophisticated spammers. To enhance spam prevention, it's recommended to implement additional measures such as IP blocking, user account verification, or content moderation. 

// Example PHP code snippet implementing additional spam prevention measures
// IP blocking
$blocked_ips = array('123.456.789.0', '987.654.321.0');
if (in_array($_SERVER['REMOTE_ADDR'], $blocked_ips)) {
    // Redirect or display an error message
    header('Location: error.php');
    exit;
}

// User account verification
if ($_SESSION['verified'] != true) {
    // Redirect to a verification page
    header('Location: verify.php');
    exit;
}

// Content moderation
if (contains_spam($_POST['content'])) {
    // Flag the content for moderation
    $moderation_needed = true;
}

function contains_spam($content) {
    $spam_keywords = array('viagra', 'free money', 'click here');
    foreach ($spam_keywords as $keyword) {
        if (stripos($content, $keyword) !== false) {
            return true;
        }
    }
    return false;
}

Keywords

Captchas spam prevention PHP forums security risks automated bots

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