Example of a persistent firewall based on systemd for Debian Jessie.
cp -r etc/iptables /etc/iptables
cp -r etc/systemd/system/iptables.service /etc/systemd/system/
cp -r etc/systemd/system/ip6tables.service /etc/systemd/system/
systemctl daemon-reload
systemctl enable iptables.service
systemctl enable ip6tables.service
systemctl start iptables.service
systemctl start ip6tables.service