<form method="post" action="dol.php">
                                                Login: <br> <input type="text" name="user"> <br>
                                                Hasło: <br> <input type="password" name="haslo"> <br>
                                                <input type="submit" name="submit" value="Zaloguj">
                                            </form>
                                            <?php
                                                $user = $_POST['user'];
                                                $pass = $_POST['haslo'];

                                                $login= mysql_fetch_array(mysql_query("SELECT  user, haslo  FROM konta WHERE user='$user' "));
                                                $passs = $login['haslo'];
                                                $pass = md5($pass);
                                                if(isset($_POST['submit'])) {
                                                    if($pass != $passs) {
                                                    header ('Location: zle.php');
                                                    exit;
                                                    }
                                                    if($user != $login['user']) {
                                                        header ('Location: zle.php');
                                                        exit;
                                                    }
                                                    $_SESSION['user'] = $user;
                                                    header ('Location: main.php');
                                                    mysql_query('UPDATE konta SET ip="'.$_SERVER['REMOTE_ADDR'].'", ip_polecony="'.$_SERVER['REMOTE_ADDR'].'" WHERE user="'.$user.'"');
                                                }
                                                ob_end_flush();
                                            ?>