<div class="container">
<div class="row">
    <di class="col-md-4 col-md-offset-4">
        <fieldset>
            <legend>Login </legend>
            <form method="post" action="loginProcess.php">
              <div class="form-group">
              <label>User name:</label>
               <input type="text" name="username" class="form-control" required>
              </div>
              <div class="form-group">
                <label>Password:</label><input type="password" name="password" class="form-control" required>
              </div>
              <div class="form-group">
               <input type="submit" name="submit" value="Login" class="btn btn-default pull-right">
            </div>
            </form>
            </fieldset>
    </di>
</div>



loginProcess.php

<?php
session_start();
include ("dbCon.php");


    $username = filter_has_var(INPUT_POST, 'username') ? $_POST['username']: null;
    $passWD  = filter_has_var(INPUT_POST, 'password') ? $_POST['password']: null;

        $sql = "SELECT passwordHash FROM te_users WHERE username = ?";
        $stmt = mysqli_prepare($conn, $sql);

        mysqli_stmt_bind_param($stmt, "s", $username);
        mysqli_stmt_execute($stmt);
        mysqli_stmt_bind_result($stmt, $passWDHash); //Get the password hash from the query results for the given username and store it in the variable indicated

        if(!empty($username)){
            if(!empty($passWD)){
                if (mysqli_stmt_fetch($stmt)) { //Check if a record was returned by the query.
                    if (password_verify($passWD,$passWDHash)){
                        $username = $_SESSION['username'];
                        $login = $_SESSION['login'];
                        $_SESSION['login'] = true;
                        header("location:index.php");
                    }
                    else
                    {
                        echo "<p>Sorry, we don't seem to have that password.</p>";
                    }
                }
                else {
                    echo "<p>Sorry, we don't seem to have that username.</p>";
                }
            }
            else {
                echo "<p>Please enter the password.</p>";
            }
        }
        else {
            echo "<p>Please enter the username.</p>";
        }


    mysqli_stmt_close($stmt);
    mysqli_close($conn);

?>




otherpage.php

this is the code that use for authentication

if( empty($_SESSION['logged_in']) )
{
     header('Location:login.php');
        exit;
}
else
{

}