yehudah

Add a meta box to all posts, pages, custom post types to add the old url you want to redirect from (old url) to the new post. 
You can use redirection plugin here: <a href="https://wordpress.org/plugins/redirection/" rel="ugc">Redirection Plugin.</a> OR The other option is the website htaccess file.
This will help you create redirects while creating or updating your site posts or pages, so you don’t need to update the old and new links when you finish updating your website.
so you don’t need to remember:
<ul>
<li>The new posts or pages url</li>
<li>which post or page I all ready redirected ?</li>
<li>repeat 50% of the process again and so on ….</li>
</ul>

Redirect To WP

This will help you sync redirects while creating or updating your site posts or pages, This will sync to the redirection plugin or htaccess.

zoltanlaczko

Using the password protection will give you extra security layer of protection from brute force hacking attacks. Additionally, it’s also an easy way to password protect your entire site, without needing to create separate WordPress users for each visitor.
When you enable the password protection, the user won’t be able to see anything – not even see the protected page – until he/she inserts the username/password. You can password protect the whole website, including the administrator pages; you can password protect the administrator pages; or you can password protect the WordPress login page.
The plugin options include:
<ul>
<li>Enabling/disabling the password protection to wp-login.php, WordPress admin pages.</li>
<li>Modifying the existing users: you can change any .htaccess user’s password and remove the users.</li>
<li>Create/modify an unlimited number of .htaccess users;</li>
<li>Protect your whole site, making it accessible to only those who have the .htaccess user.</li>
</ul>
This plugin is originally was based on <a href="https://wordpress.org/plugins/htaccess-site-access-control/" rel="ugc">.htaccess Site Access Control</a>. That plugin was working fine but it was abandoned for years and not compatible with the latest WordPress. Most part of the plugin were refactored and translated.

htaccess protect

htaccess protect - Protect your wordpress login or admin pages with password.

Redirect To WP vs htaccess protect