I can build the SimpleFirewall application (https://developer.apple.com/documentation/networkextension/filtering_network_traffic ) using xcode:
After I run the application, seems can't block any traffic.
I find there is some logs from network extension process:
networkd_settings_read_from_file Sandbox is preventing this process from reading networkd settings file at "/Library/Preferences/com.apple.networkd.plist", please add an exception.
Any step I am missing ?