Roberto, thank you for this clarification. I, too, thought IPfire was failing because my IPfire with proxy in transparent mode was failing to block https sites on blacklists.
Can we get the UI updated (in bright color) to highlight that URL filter will not filter https sites if proxy is in transparent mode, please?
Is it possible to change the default behavior to get the transparent proxy to filter https pages? The advent of LetsEncrypt and security means many, many pages are https only now and therefore significantly reducing the effectiveness and control of a transparent proxy.
With a transparent proxy you must break the HTTPS traffic. This is not allowed in many countries and never good practice!
The standard proxy mode gets all HTTP(S) requests with the target URI. Thus it is possible to block/redirect this request without breaking the contents of the packet.