remote time machine
Super easy: you can use a Linux server running
netatalk as a Time Machien backup drive. Easy peasy.
Instructions at the link, but in brief:
sudo apt install build-essential devscripts debhelper cdbs autotools-dev dh-buildinfo libdb-dev libwrap0-dev libpam0g-dev libcups2-dev libkrb5-dev libltdl3-dev libgcrypt11-dev libcrack2-dev libavahi-client-dev libldap2-dev libacl1-dev libevent-dev d-shlibs dh-systemd avahi-daemon libc6-dev libnss-mdns git clone https://github.com/adiknoth/netatalk-debian cd netatalk-debian debuild -b -uc -us sudo dpkg -i ../*.deb sudo nano /etc/netatalk/afp.conf
You probably want to make a new user with
adduser --home $BACKUP_DIR and point the backups to there, adding
valid users = $user to
Give it a while for avahi to kick in (I rebooted) and then you should see it in the list of Time Machine drives you can add in Settings.