I want to run an application on macOS, but preventing it from making any type of network access, or any type of internet access.
I have seen the following possibilities:
Use the built-in firewall. Unfortunately, this blocks only inbound connections, not outbound.
I have seen Little Snitch. However, it feels uncomfortable from a security standpoint to install a closed-source software on my system that has so deep an access to everything I do.
Ideally, I would like to do that myself. Is it possible to restrict an app's access to network ressources on macOS ? Maybe start it in a sandbox mode somehow?