<?php 
 $username='admin';
 $password='letmein';

 if (isset($_SERVER['PHP_AUTH_USER']) &&
  isset($_SERVER['PHP_AUTH_PW']))
  
  {
   if ($_SERVER['PHP_AUTH_USER'] == $username &&
    $_SERVER['PHP_AUTH_PW'] == $password)
    echo "You are now logged in";
    else die("Invalid username or pass");
   
  }
  else
  {
   header('WWW-Authenticate: Basic realm="Restricted Section"'); 
   header('HTML/1.0 401 Unauttorized');
   die("Please enter your username and password");
}?>

else
  {
   header('WWW-Authenticate: Basic realm="Restricted Section"'); 
   header('HTML/1.0 401 Unauttorized');
   die("Please enter your username and password");
}