modprobe ipv6
ip tunnel add he-ipv6 mode sit remote x local y ttl 255
ip link set he-ipv6 up
ip addr add z dev he-ipv6
ip route add ::/0 dev he-ipv6
ip -f inet6 addr

root@toolmaster:~# ip -f inet6 addr
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 16436
    inet6 ::1/128 scope host
       valid_lft forever preferred_lft forever
3: eth1: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qlen 1000
    inet6 fe80::226:18ff:fea8:db1e/64 scope link
       valid_lft forever preferred_lft forever
9: he-ipv6: <POINTOPOINT,NOARP,UP,LOWER_UP> mtu 1480
    inet6 2001:470:27:88f::2/64 scope global
       valid_lft forever preferred_lft forever
    inet6 fe80::8027:2ab7/128 scope link
       valid_lft forever preferred_lft forever