Thank you for responding, and so quickly. You are correct on the first point, I don't have multicast entitlements in my app (got a nasty crash when I tried), but I am mostly attempting to send multicast udp packets, and kept hitting a roadblock with these permissions. The issue is with the Local Network Privacy permissions. The reason I think it is this, and not incorrect API usage, is I had the app installed on a brand new Mac Mini, and could not send UDP multicast packets from the app. I then ran the app from the Terminal, and it worked just fine. I realized I was missing these network permissions, and re-built and reinstalled it with these permissions enabled. The app worked temporarily after re-installing, but then restarting the machine, the app would again stop working and still not allow me to send these packets. It would work from the terminal (which says that the API's are used correctly. BSD sockets being what they are...) I then created a new user on that machine, and had no issues with these permissions or the network, even after restarting the machine. So I deleted the original user, and used the second user for the app, which was fine in this case, but horrid if I ever had to ask a user to do it. In the System Settings > Privacy & Security > Local Network the app in all cases had this enabled. There is no way to remove and re-force the request from this settings menu, and on my development machines, I see hundreds of these permissions for my app in this menu, with no way to remove them. This is on OSX 15.6.