The Ban module allows an administrator to ban visits to his/her site from specifick IP addresses.
This functionality exist already in Drupal 7 as a part of the System module.
In Drupal 8 the functionality is included as a separate module in the core.
The module is not enabled by default in the Standard profile, so you'll need to go to your "Extend" page and enable it.
How to ban an IP address?
Go to Configuration - People - IP address ban.
Enter an IP address and click on Add.
Om te verwijderen: klik op Verwijderen naast het IP adres.