Comment blacklisting works well, but what if you actually want to stop someone from even reading your blog? This plugin will take care of that for you.
It uses .htaccess file modifications to deny access to your blog from particular IP addresses (Deny from) and then follows up with an ErrorDocument 403 redirect to a URL of your choice. It doesn’t hook into WordPress, which makes it a lot faster due to no database or PHP calls.

WP-BlockYou

A plugin that can be used to block or "ban" users via their IP address from viewing your blog, and then redirecting them to a URL of your ch …

By far the simplest country allowlist plugin available for WordPress. Locks admin panel and XMLRPC access to a given list of allowed countries using <a href="https://apis.qweb.co.uk/ip-lookup/" rel="nofollow ugc">QWeb’s IP to country lookup API</a>.
This is free open source software (FOSS), which you’re welcome to either use as-is, or fork and further develop under the very permissive terms of the <a href="LICENSE" rel="nofollow ugc">MIT license</a>.
Out of the box, this is most likely the simplest, most efficient plugin for restricting access to your WordPress admin panel to an allowlist of specific countries. Simply install and activate the plugin, obtain an access key via the QWeb Ltd API console, and enter your access key in the plugin settings. The plugin will automatically determine your own country and add this to the allowlist, and you can add other countries to the list as you like.
Countries are entered as comma separated <a href="https://en.wikipedia.org/wiki/ISO_3166-1_alpha-2#Officially_assigned_code_elements" rel="nofollow ugc">ISO 3166-1 alpha-2 country codes</a> in a single field, making it super easy to copy & paste the same list across multiple websites.
This plugin also restricts access to the WordPress XMLRPC mechanism, using the same country allowlist.
You can optionally choose to allow or disallow access through known public proxy servers, even if they’re located in an allowed country.
The plugin creates a cache of IP information and automatically clears cache files older than one week. This reduces the number of lookup requests and keeps your website responsive, without creating an unnecessarily large cache.
As a single 25kb file, this is an exceptionally lightweight plugin. Built to be efficient, and using QWeb’s incredibly responsive <a href="https://apis.qweb.co.uk/ip-lookup/" rel="nofollow ugc">IP lookup API</a>, the Admin Country Allowlist plugin should be a part of your standard security kit for any WordPress websites that you manage.
This plugin relies on <a href="https://apis.qweb.co.uk/ip-lookup/" rel="nofollow ugc">QWeb’s IP to country lookup API</a> for IP to country lookups, and will not function without an active API key from this service. QWeb does provide a FREE tier for this API service, suitable for most websites. Please refer to the <a href="https://apis.qweb.co.uk/console/eula" rel="nofollow ugc">QWeb Ltd API Terms of Use</a> and <a href="https://www.qweb.co.uk/privacy-policy" rel="nofollow ugc">QWeb Ltd Privacy Policy</a>.

Admin Country Allowlist

By far the simplest country allowlist plugin available. Locks admin panel and XMLRPC access to a given list of allowed countries.

WP-BlockYou vs Admin Country Allowlist