[Unit]
Description=Enable IPv6 forwarding
After=network-online.target

[Service]
Type=oneshot
RemainAfterExit=yes
ExecStart=/sbin/sysctl net.ipv6.conf.all.forwarding=1
ExecStart=/sbin/ip addr add 2001:14b8:100:8397::1/64 dev eth0

ExecStop=/sbin/sysctl net.ipv6.conf.all.forwarding=0
ExecStop=/sbin/ip addr del 2001:14b8:100:8397::1/64 dev eth0

[Install]
WantedBy=multi-user.target