IP=/usr/sbin/ip
ipv4=`$IP addr show dev ppp0 | /bin/grep inet | /usr/local/bin/mawk '{print $2}'`
ipv6=$(/usr/bin/printf "2002:%02x%02x:%02x%02x::1" `echo $ipv4 | /usr/bin/tr "." " "`)

$IP -6 route flush dev tun6to4
$IP link set dev tun6to4 down
$IP tunnel del tun6to4

if test ${1:-fnord} = stop; then exit 0; fi

# echo $ipv4 - $ipv6

$IP tunnel add tun6to4 mode sit ttl 64 remote any local $ipv4
$IP link set tun6to4 up
$IP -6 addr add $ipv6/16 dev tun6to4
$IP -6 route add 2000::/3 via ::192.88.99.1 dev tun6to4 metric 1
# $IP -6 route add 2000::/3 via ::139.18.38.73 dev tun6to4 metric 1

# uni leipzig: 139.18.38.73