# The loopback network interface
auto lo
iface lo inet loopback

# for Routing
auto vmbr1
iface vmbr1 inet static
        address XXX.XXX.XXX.XXX # private IP
        netmask 255.255.255.0
        bridge_ports none
        bridge_stp on
        bridge_fd 0
        post-up echo 1 > /proc/sys/net/ipv4/ip_forward
        post-up iptables -t nat -A POSTROUTING -s 'XXX.XXX.XXX.XXX/24' -o vmbr0 -j MASQUERADE
        post-down iptables -t nat -D POSTROUTING -s 'XXX.XXX.XXX.XXX/24' -o vmbr0 -j MASQUERADE

# vmbr0: Bridging. Make sure to use only MAC adresses that were assigned to you.
auto vmbr0
iface vmbr0 inet static
        address XXX.XXX.XXX.XXX # public IP
        netmask 255.255.255.0
        network XXX.XXX.XXX.XXX
        broadcast XXX.XXX.XXX.XXX
        gateway XXX.XXX.XXX.XXX
        bridge_ports eth0
        bridge_stp off
        bridge_fd 0

iface vmbr1 inet6 static
        address XXXX:XXX:XXXX:: # routed /48 from HE
        netmask 48

auto he-ipv6
iface he-ipv6 inet6 v4tunnel
        address XXXX:XXX:XXXX:XXX::2 # client /64 from HE
        netmask 64
        endpoint XXX.XXX.XXX.XXX
        local XXX.XXX.XXX.XXX
        ttl 255
        gateway XXXX:XXX:XXXX:XXX::1 # server /64 from HE
        post-up /sbin/ip -f inet6 route add XXXX:XXX:XXXX:XXX::1 dev he-ipv6
        post-up /sbin/ip -f inet6 route add default via XXXX:XXX:XXXX:XXX::1
        pre-down /sbin/ip -f inet6 route del default via XXXX:XXX:XXXX:XXX::1
        pre-down /sbin/ip -f inet6 route del XXXX:XXX:XXXX:XXX::1 dev he-ipv6
        post-up echo 1 >| /proc/sys/net/ipv6/conf/all/forwarding
        post-up echo 1 > /proc/sys/net/ipv6/conf/all/proxy_ndp