[Unit]
Description=Save iptables firewall
DefaultDependencies=no
After=iptables.service
# fail immediately if iptables.service has not been started
Requisite=iptables.service
Before=shutdown.target

[Service]
Type=oneshot
RemainAfterExit=no
ExecStart=/usr/local/lib/iptables-helper save

[Install]
WantedBy=shutdown.target