Protecting backend logins by limiting login attempts

Many of the existing WordPress sites use the default backend login to let users login, while some sites use custom frontend login forms. The backend login is one of the most frequently used places to gain access to user accounts by guessing the login details or trying random usernames and password combinations through brute-force attacks. Even if the attacker doesn't get access to the user account, your site will be flooded with login requests. Their requests will consume most of the memory in your server. This is called a Distributed Denial of Service (DDoS) attack, where your server resources will be temporarily or permanently unavailable to the intended users. So, we need to prevent users from trying unlimited combinations of usernames and passwords on the login page. We can implement this by limiting invalid login attempts...