Setup Networked Time Machine Drive

Install samba and avahi-daemon. Samba shares the drive and avahi makes it work with apple (bonjour, etc)

sudo apt-get install samba avahi-daemon

Add user for time machine backups only and set password

sudo adduser timemachine

Take ownership of the drive

sudo chown -R timemachine: /mnt/TMDrive

Edit the Samba configuration file:

sudo nano /etc/samba/smb.conf

Contents of the file

[backups]
 comment = Backups
 path = /mnt/TMDrive
 valid users = timemachine
 read only = no
 vfs objects = catia fruit streams_xattr
 fruit:time machine = yes

More info about config files: https://www.samba.org/samba/docs/current/man-html/smb.conf.5.html
More info about vfs_fruit: https://www.samba.org/samba/docs/current/man-html/vfs_fruit.8.html

Test Samba configuration

sudo testparm -s

Create a password for the samba drive

sudo smbpasswd -a timemachine

Restart the service to apply new config file

sudo service smbd reload

Modify the avahi config file:

sudo nano /etc/avahi/services/samba.service

Contents of the file:

<?xml version="1.0" standalone='no'?><!--*-nxml-*-->
<!DOCTYPE service-group SYSTEM "avahi-service.dtd">
<service-group>
  <name replace-wildcards="yes">%h</name>
  <service>
    <type>_smb._tcp</type>
    <port>445</port>
  </service>
  <service>
    <type>_device-info._tcp</type>
    <port>9</port>
    <txt-record>model=TimeCapsule8,119</txt-record>
  </service>
  <service>
    <type>_adisk._tcp</type>
    <port>9</port>
    <txt-record>dk0=adVN=backups,adVF=0x82</txt-record>
    <txt-record>sys=adVF=0x100</txt-record>
  </service>
</service-group>sudo nano /etc/avahi/services/samba.service

Restart Avahi daemon:

sudo service avahi-daemon restart