Captive portal | Whitelist-only Internet | Internet filtering
October, 2020 - this software has become open source
DNS Redirector software
... offers Captive portal, Whitelist-only Internet, and Internet filtering features - you can implement any combination of these features. The software is intended to run on Windows servers - as a recursive DNS service between client/end-user devices on the LAN and your AD DNS service (the Microsoft DNS service) or a 3rd party DNS server, such as your ISP, Google DNS, etc.