[Unit]
Description=Save ip6tables rules
Requisite=ip6tables.service
Before=network.target
After=ip6tables.service
ConditionPathIsDirectory=/var/lib/ip6tables

[Service]
Type=oneshot
RemainAfterExit=yes
ExecStart=/bin/true
ExecStop=/bin/sh -c "/sbin/ip6tables-save $SAVE_OPTIONS > /var/lib/ip6tables/rules-save"

[Install]
WantedBy=multi-user.target