Hackers typically search for the common login page wp-login.php. Likewise, you may want to force your website visitors to login through your portal, and not the default Wordpress login page, but still allow administrators access to the appropriate page.
Modify your themes function.php file.
To limit access to the administrators section for logged in users, locate your functions.php file within your theme directory. Append the following code to the bottom of that file, typically under the the edit below this line section.