/etc/systemd/system/shutdown-on-eth-fail.service


[Unit]
Description=Shutdown on Ethernet Failure
After=eth-monitor.service

[Service]
Type=oneshot
ExecStart=/bin/sh -c 'if [ $(journalctl -u eth-monitor.service --since "5 minutes ago" | grep -c "is down") -ge 5 ]; then /sbin/shutdown -h now; fi'

[Install]
WantedBy=multi-user.target