Set Up a Mac Mini as a Headless Server for Home Network

My Apple TimeCapsule has been running flawlessly for 14 years, providing a backup server for our fleet of Macs long after the TC was discontinued. It still works well, albeit slowly due to the slow disk and network performance. But now Apple has decreed that AFP will be deprecated and no longer supported in future releases of MacOS. So, this is the main impetus of this exercise - to replace the TimeCapsule with a server which can host Time Machine-like functionality. I could have gone with one of several NAS offerings from Synology and others but I had a perfectly functional M1 Mac Mini in a drawer that I was gifted. You can't beat free.

So, let's configure the M1 Mac Mini as a network server for Time Machine backups, file sharing, printer sharing, local iCloud, and other tasks. We will run it headless connected to the primary network switch by a wired connection.

1. Update MacOS : currently using MacOS 15.7 'Sequoia'

2. Consider resetting to a clean install (recommended):
	https://support.apple.com/en-us/102664

3. Create users:
	a. Admin user: the first user you created

	b. Basic user (unprivileged but with sudo access): create an unprivileged second user for logins
		Set up sudo access for basic user:
			Log in as adminstrator and 
			# visudo
		Add line:
			seconduser		ALL = (ALL) ALL

	c. Sharing Users: Create another user to access the shared folders and volumes. You can use the MacOS Syetem Settings > Users and Groups to add a Sharing User but this has been associated with problems with Windows computers being able to use shares (see https://apple.stackexchange.com/questions/469442/unable-to-select-sharing-only-user-when-setting-up-file-sharing).

	An alternative if the MacOS Sharing User setup doesn't work for your Win hosts is to set it up manually which does work with Windows ime:

		sudo dscl . -create /Users/tmuser
		sudo dscl . -create /Users/tmuser RealName "TM_Server_User" (You should use another name)
		sudo dscl . -create /Users/tmuser UserShell /usr/bin/false
		sudo dscl . -create /Users/tmuser NFSHomeDirectory /var/empty

		You can place this user in the staff group (GroupID 20). You could consider creating multiple sharing users as above to keep each remote user's TM backups separate. In this case, create users 'tmuser1', 'tmuser2', etc. and groups 'tmuser1', 'tmuser2';, etc. and assign these to your various TM client machines.

		sudo dscl . -create /Users/tmuser PrimaryGroupID 20
		Or:
		sudo dscl . -create /Groups/[groupname]
		Find a unused group number:
		dscl . -list /Groups PrimaryGroupID | awk '{print $2}' | sort -n
		Assign this:
		sudo dscl . -create /Groups/[groupname] PrimaryGroupID [newGID]
		sudo dseditgroup -o edit -a tmuser -t user [groupname]
		Repeat for each individual TM/Network user you wish to create

		Now assign a ID number >500 not in use. First, see what numbers are asigned:
		dscl . -list /Users UniqueID | awk '{print $2}' | sort -n
		Then, assign that unused number:
		sudo dscl . -create /Users/tmuser UniqueID 510 (or whatever)

		Now, check that it was all correct:
		dscl . -read /Users/tmuser

		Now, go to System Settings > Users and Groups and see that your new users are listed. Set a strong password for each new user.

4. Set up network:
	a. Turn off WiFi.
	b. Set wired interface IP address to a static one
	c. Unset 'Automatically join this networK' in System Settings > WiFi
	d. Delete (Forget) all saved networks
	e. Set require administrator password to turn wifi on or change networks
	f. MacOS has an unfortunate habit of turning the wifi back on randomly. You can set the System Settings to 'Require Administator to turn Wifi on' or to change networks. You can also delete any saved networks. But if you reboot the server, Wifi may be turned on again. Best here is to make a new Location. Duplicate 'Automatic' and rename it 'Wired' or something. Then, in this 'Wired' Location, you can make Wifi inactive or delete the wifi service altogether.
	
5. Set up remote access:
	MacOS has 2 methods of remote access: Screen Sharing and Remote Wanagement, both found in the Sharing pane of System Settings and both are based on vnc.
	Screen Sharing works but I've found that disconnections are more frequent.
	For that reason, enable Remote Management and then use a VNC client to connect. For an older Macs, RealVNC is good. For a more modern OS, Screens works well, but there are many other options.
	Log into your Mac server remotely to confirm remote access is working.

6. Set to restart on power loss.

7. Set to auto login to a specific user such as seconduser.

8. Set up not to go to a lock screen:
	System Settings >> Lock Screen >> Require Password after Screen saver begins or screen is turned off > set to 'Never'

9. Fix headless video issues with dummy HDMI plug or software (BetterDisplay): On my M1 Mac Mini, I seemed to have no problems running it headless. In that case, the resolution was set to 1920x1080 with no other options displayed. The slow response, choppy graphics, and so on reported on the web were not seen (but, then. I am not playing games or streaming video over the vnc connection). I then used a NewerTech dummy HDMI plug and I noticed no difference except other resolutions were visible in System Settings.

10. Prevent the Mac from sleeping:
	caffeinate: This disables sleep as log as a process ('assertion') is running. You can find the PID of the login window and prevent sleep as long as the user is logged in with:
		caffeinate -w <PID>
	pmset: IMO, a better approach
		sudo pmset disablesleep 0

11. Now, power down and connect to router/switch with wired connection then power up. After power up, log in with ssh or VNC and issue command 'sudo pmset disablesleep 0'

12. Attach a fast USB disk to a USB port (Thunderbolt/USB3.2 if available) and configure.
	
	a. Time Machine Server https://support.apple.com/en-euro/guide/mac-help/mchl31533145
		Create shares:
			Format the USB disk as APFS
			Create a new volume for each machine which will be using the new backup server.
			If you're migrating backups from a TimeCapsule, copy the sparsebundle from the TimeCapsule disk to the new shared folder.
		Set sharing permissions:
			Set shares to be shared as SMB.
		    Select the backup Volume.
		    Under 'Advanced Settings', set the share to be used as a Time Machine backup 
			Set 'Read and Write' permissions for appropriate TM_Server_User or other sharing user you created above.
			You can also give 'Read and Write' permissions to the server's Staff group as is done by default, but this is not necessary.
			Set 'Everyone' to have 'No Access'
		Connect execute first backup:
			Usually, this should be done over a wired connection, assuming you are not trying to migrate old TM backups
		Connect and use previous sparsebundle:
		    If you're migrating from a TimeCapsule, copy the sparsebundle from the TimeCapsule disk to the empty new shared folder.
		    Then, on the remote host, go the Time Machine in System Settings or System Preferences, delete the existing Time Machine backup disk (hosted on the Time Capsule), and select the new shared volume as the Time Machine backup disk, you will be asked if you want to use the existing sparsebundle.

	b. File Sharing:
		You can create a single Volume on your backup disk for shared files and then create folders which may be shared to all users, a single user, groups, or subgroups. This quickly gets complex but for small home networks with limited users and roles, the native unix-y user/group permission system is pretty standard.
		https://support.apple.com/en-euro/guide/mac-help/mh17131/15.0/mac/15.0

	c. Content caching:
		Set up content caching server: https://support.apple.com/en-euro/guide/mac-help/mchl3b6c3720/15.0/mac/15.0 on the server.
		Set up caching server and clients: https://support.apple.com/en-euro/guide/mac-help/mchl9b56e1cf/15.0/mac/15.0

	d. Printer Sharing (if you have a printer/scanner which is not wifi or ethernet enabled)

	e. Others (Plex, Jellyfin, Emby, etc.):
		For Jellyfin: Set up: https://github.com/Digital-Shane/jellyfin-on-macos?tab=readme-ov-file
					  Comments: https://www.reddit.com/r/selfhosted/comments/1jlvg3p/the_ultimate_guide_for_hosting_jellyfin_on_macos/

Other/General References:
https://stealthpuppy.com/mac-mini-home-server/
https://www.intego.com/mac-security-blog/how-to-set-up-your-own-mac-server-with-an-old-or-new-mac/