#!/bin/sh

set -e

ip4=$1
echo "$ip4" | grep -q '^[0-9]*\.[0-9]*\.[0-9]*\.[0-9]*$' || \
{ echo 'Syntax: $0 a.b.c.d'; exit 1; }

prefix=$(printf '%02x%02x:%02x%02x\n' $(echo $ip4 | sed 's/\./ /g'))

ip tunnel add 6to4 mode sit remote any local $ip4
ip link set dev 6to4 up
ip addr add 2002:$prefix::1/16 dev 6to4
ip -6 route add ::/0 via ::192.88.99.1 dev 6to4 metric 1026