Restricting your admin area to be accessible from a single IP is a great way to secure your Joomla and WordPress site. To do this, without having to write any complex .htaccess files or anything else, simply click on the Secure Admin button.
The tool will ask you to enter the IP address you're going to use to access your admin panel from. If you don't know it, you can use a website like whatsmyip.com. Once you enter it, press the Continue button to proceed.
Now, your /wp-admin or /administrator folder will be accessible only from the IP address you've entered! Note, that you can add more than one IP address to the list of allowed IPs or remove any existing entries.