Lulu
Lulu

LuLu is the free, shared-source macOS firewall that aims to block unknown outgoing connections, unless explicitly approved by the user.
https://objective-see.com/products/lulu.html
drduh/OS-X-Security-and-Privacy-Guide,drduh/OS-X-Yosemite-Security-and-Privacy-Guide,drduh/macOS-Security-and-Privacy-Guide,ScheerMT/OS-X-Yosemite-Security-and-Privacy-Guide