LuLu

Looks like changes will need to be made for LuLu to work on Big Sur: https://github.com/objective-see/LuLu/issues/183

Play stupid games, win stupid prizes. If you cannot afford Little Snitch or don't want to pay for it or just prefer open source, install LuLu. It's a free and open source alternative to LS application firewall. [1] You can install it through Homebrew or download binaries manually [2]. [1] https://github.com/objective-see/LuLu [2] https://objective-see.com/products/lulu.html

On macOS, we got a port of OpenBSD pf (probably not up to date though). I've been able to convert hosts files to OpenBSD pf format in, when was it, 2002? What you'd need to do is create an anchor. Perhaps there's a GUI for it as well for those who prefer. There's at least pfBlockerNG which basically does that for PfSense. [1] FWIW, all of this existed before Pi-Hole (or Raspberry Pi for that matter). IIRC there was also a converter script for hosts files to IPTables rules. Is it possible to import such rules to Little Snitch? That's the go to firewall on macOS, though it is proprietary. There's also LuLu, a FOSS firewall for macOS. [2] Now, from my memory, these block lists did cost quite some memory on a machine with 512 MB RAM. Even though it'd do dedup. What one could also do is build up a VPN with a remote server (in the cloud, or at

On the cheaper side on the spectrum but not quite as cheap as TripMode, there is Vallum: https://vallumfirewall.com I've been using it for years and the only feature I miss is domain/subdomain blacklisting. If there is no need for such a granular control of outgoing connections for any given application, there's also the no-cost and open-sourced LuLu: https://github.com/objective-see/LuLu