login.php

<html>
<head>
<title>Login Form</title>
</head>
<body>
<h2>Login Form</h2>
<form method="post" action="checklogin.php">
User Id: <input type="text" name="uid"><br>
Password: <input type="password" name="pw"><br>
<input type="submit" value="Login">
</form>
</body>
</html>

checklogin.php

<?php
$uid = $_POST['uid'];
$pw = $_POST['pw'];

if($uid == 'arun' and $pw == 'arun123')
{	
	session_start();
	$_SESSION['sid']=session_id();
	header("location:securepage.php");
}
?>

securepage.php

<?php
	session_start();
	if($_SESSION['sid']==session_id())
	{
		echo "Welcome to you<br>";
		echo "<a href='logout.php'>Logout</a>";
	}
	else
	{
		header("location:login.php");
	}
?>

logout.php

<?php

	echo "Logged out scuccessfully";
    
    session_start();
	session_destroy();
	setcookie(PHPSESSID,session_id(),time()-1);

?>