You can also load redwood into ClearOS. Hopefully they will natively support it soon. It replaces both squid and dansguardian; is a similar alternative to dansgardian only it's more powerful. It examines HTTPS, so you can handle all HTTPs traffic the way you were used to handling HTTP.
It can be downloaded here: https://github.com/andybalholm/redwood
The community version doesn't have a GUI. If you want a GUI, you need to contact Compass Foundation 855-530-8090
Note: I am not an associate of Compass Foundation but I do buy from them.