Yes, you can configure a computer to connect to your local network while restricting access to the internet.
Yes, you can configure a computer to connect to your local network while restricting access to the internet.
You have a 2007 Mac Mini sitting idle and you're aiming to convert it into a server for time machine backups on your local network. The Mac OS X version running is quite old and poses security risks, but you're looking to avoid connecting it to the internet while still using LAN connectivity. You also want to take advantage of features like screen sharing. This setup should work seamlessly over your local network, just like Time Machine, without needing an external drive.
Probably I’d have to disable all incoming connections, but will the network sharing remain functional?
Note: This screenshot comes from my laptop, though the preferences panel looks identical on the older Mac Mini version.
Edited February 1, 2020 by Twilight
As long as it isn’t actively connected to something online, the risk shouldn’t be high. The main concern is using a web browser on it, so avoid that. You don’t necessarily need to adjust the firewall settings to block it—actually, that approach is poor because the device will still attempt to connect, which could lead to instability in the OS or software. Instead, assign a static IP address and leave the gateway or DNS fields blank so it won’t try to go online. Ideally, keep its IP reserved on the DHCP server but outside the DHCP range to prevent other devices from accessing it.