[Unit]
Description='share internet'
Conflicts=dnsmasq.service
Wants=network.target
Before=network.target
BindsTo=sys-subsystem-net-devices-%i.device
After=sys-subsystem-net-devices-%i.device

[Service]
Type=simple
EnvironmentFile=/etc/conf.d/share-internet@%i
ExecStartPre=/usr/bin/dnsmasq --test
ExecStartPre=/usr/bin/iptables -t nat -A POSTROUTING -o $EXTERNAL_DEVICE -j MASQUERADE
ExecStartPre=/usr/bin/ip6tables -t nat -A POSTROUTING -o $EXTERNAL_DEVICE -j MASQUERADE
ExecStartPre=/usr/bin/sysctl -w net.ipv4.ip_forward=1 net.ipv6.conf.all.forwarding=1
ExecStartPre=/usr/bin/ip link set %i up
ExecStartPre=/usr/bin/ip addr add ${IP4_ADDRESS}/${IP4_NETMASK} dev %i
ExecStartPre=/usr/bin/ip addr add ${IP6_ADDRESS}/${IP4_NETMASK} dev %i

ExecStart=/usr/bin/dnsmasq -k --user=dnsmasq --pid-file \
          --conf-file=/etc/dnsmasq.conf \
          --interface=%i \
          --dhcp-range=${IP4_SUBNET},infinite \
          --dhcp-range=${IP6_SUBNET},ra-stateless,ra-names,infinite \
          --dhcp-option=3,${IP4_ADDRESS}  \
          --dhcp-option=5,${IP4_ADDRESS}  \
          --enable-ra \
          --no-daemon
ExecReload=/bin/kill -HUP $MAINPID

ExecStopPost=/usr/bin/ip addr flush dev %i
ExecStopPost=/usr/bin/ip link set %i down
ExecStopPost=/usr/bin/sysctl -w net.ipv4.ip_forward=0 net.ipv6.conf.all.forwarding=0
ExecStopPost=/usr/bin/iptables -t nat -D POSTROUTING -o $EXTERNAL_DEVICE -j MASQUERADE
ExecStopPost=/usr/bin/ip6tables -t nat -D POSTROUTING -o $EXTERNAL_DEVICE -j MASQUERADE