Grizzly Hills

Setting up an Ubuntu machine to act as an Apple Time Machine server is surprisingly simple. This example uses a directory on the boot drive (/srv/netatalk/time-machine), but it’s more likely that you want to use a directory on a large disk.
Here are the steps…

Install the needed packages:

sudo apt install netatalk avahi-daemon

Edit the netatalk config file:

sudo vi /etc/netatalk/afp.conf

Add a section for your Time Machine:

[Time Machine]
  path = /srv/netatalk/time-machine
  time machine = yes

Create a directory to act as the Time Machine drive:

sudo mkdir -p /srv/netatalk/time-machine
sudo chown nobody:nogroup /srv/netatalk/time-machine
sudo chmod 777 /srv/netatalk/time-machine

Restart netatalk:

sudo service netatalk restart

Now, on your Mac, you should be able to open the Time Machine settings in System Preferences and use Select Disk… to pick your new Time Machine backup drive.

Update for Ubuntu 20.04 and other notes

Since I first wrote this, I have updated to Ubuntu 20.04 and everything still seems to work. However, I never made it clear that you must make sure your backup drive is available and connected on your Mac before you can use it as a Time Machine backup drive.

Once your drive is set up under Ubuntu, go to your Mac and open a Finder window. Under the Network section in the sidebar, you should see your Ubuntu machine listed. Double-click on the machine name, and you should see any shared folders on the machine. You may have to click on the Connect button in the upper right of the window to login before you can use the drive.

Once you are logged in, you should then be able to use the drive with Time Machine.

Setting up Samba under Ubuntu 19.10 is relatively easy. This guide will show how to install Samba itself, then configure both a public drive meant to be shared among multiple users, and a per-user drive.

NOTE: This guide assumes your linux machine is on your local network.

First, install both samba and smbclient:

sudo apt install samba smbclient

Next, create a directory that will be the shared public drive, and set its ownership:

sudo mkdir -p /srv/samba/public
sudo chown nobody:nogroup /srv/samba/public
sudo chmod 777 /srv/samba/public

Now it’s time to configure Samba. There’s two basic things that need to be configured: setting the user security, and adding the public drive.

To set the user security, set security = user in the [global] section of /etc/samba/smb.conf.

Enable the per-user drive in /etc/samba/smb.conf:

[homes]
    comment = Home Directories
    browseable = no
    read only = no

To add the public drive, add this section to the end of /etc/samba/smb.conf:

[public]
   comment = Public Files
   path = /srv/samba/public
   browsable = yes
   guest ok = yes
   read only = no
   create mask = 0755

Now, restart the Samba services to pick up these configuration changes:

sudo systemctl restart smbd.service nmbd.service

Since Samba doesn’t use the linux login credentials for a user, you must add each user that needs access to a shared drive using the smbpasswd command:

sudo smbpasswd -a <unix username>

Also, if you’re running a firewall on your linux machine, you’ll probably have to allow access for your local network. You can allow specific machines, or a subnet. I use ufw to control my firewall configuration, so for me I simply allowed all access for my internal network:

sudo ufw allow from 192.168.0.0/16

To connect to a drive from Windows, I right-click on the Network item in File Explorer and select Map network drive..., and use \\<hostname>\public or \\<hostname>\<unix username> as the Folder.

To connect to a drive from the Mac, I use Go -> Connect to Server... in the Finder, then use smb://<hostname>/public or smb://<hostname>/<unix username> as the address.