php后台登陆不进去

# 检查服务器配置文件
sudo nano /etc/nginx/nginx.conf

# 确保端口未被占用
sudo netstat -tuln | grep 80

// 检查数据库连接配置
$servername = "localhost";
$username = "username";
$password = "password";
$dbname = "database_name";

$conn = new mysqli($servername, $username, $password, $dbname);

if ($conn->connect_error) {
    die("连接失败: " . $conn->connect_error);
}

// 检查登录验证代码
if ($_SERVER["REQUEST_METHOD"] == "POST") {
    $username = $_POST['username'];
    $password = $_POST['password'];

    // 防止SQL注入
    $stmt = $conn->prepare("SELECT * FROM users WHERE username = ?");
    $stmt->bind_param("s", $username);
    $stmt->execute();
    $result = $stmt->get_result();

    if ($row = $result->fetch_assoc()) {
        if (password_verify($password, $row['password'])) {
            // 登录成功
        } else {
            echo "密码错误";
        }
    } else {
        echo "用户名不存在";
    }
}

# 检查网络连接
ping www.google.com

# 检查防火墙设置
sudo ufw status

# 检查用户权限
sudo chown -R www-data:www-data /var/www/html
sudo chmod -R 755 /var/www/html