custom rule that uses a match rule: Custom rules allow you to create tailored rules to suit the exact needs of your applications and security policies. Now, you can restrict access to your web applications by country/region. As with all custom rules, this logic can be compounded with other rules to suit the needs of your application.

To create a geo-filtering custom rule in the Azure portal, simply select Geo location as the Match Type, and then select the country/region or countries/regions you want to allow/block from your application.