Hosting a website now-a-days is a very common thing. So is to set a web server. It is not an issue if we are only serving static pages i.e. plain html, stylesheet, and javascript (client side). But when it comes to server-side scripting (using php, nodejs, cgi), authorising the user is a very common thing. So, it become very important to check the validity of each request. The increasing number of websites is encouraging the brute force attacks on login pages, where user is to be authorised. So, to avoid the attacks, it is essential to set the proper filtering on the server machine.