#! /bin/sh
#
# local-ipv6-networking - sets up IPv6 networking using a 6to4 tunnel
#
# Copyright 2004 by Nathaniel W. Turner <nate@houseofnate.net>
# This program is published under GNU GPL version 2.
# See: http://www.gnu.org/licenses/gpl
#
# Depends: iproute, perl
#
# This script sets up a 6to4 tunnel for IPv6 networking from any IPv4 machine.
# The IPv6 prefix is determined at runtime, making this script suitable for
# workstations that get their IPv4 address from DHCP.
#     It can be installed in /usr/local/sbin and called from
# /etc/network/interfaces or installed in /etc/init.d and used as a sysv
# initscript.
#
# Example usage with /etc/network/interfaces (recommended):
#
# iface eth0 inet dhcp
#   up /usr/local/sbin/local-ipv6-networking up eth0
#   down /usr/local/sbin/local-ipv6-networking down eth0
#

PATH=/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin
NAME=local-ipv6-networking
DESC="IPv6 networking (6to4 tunnel)"
DEFAULT_IPV4_IF=eth0

# Gracefully exit if the iproute package has been removed.
test -x /bin/ip || exit 0

set -e

# Uncomment the following line for debugging:
#set -x

# determines the ipv4 interface
if [ -n "$2" ]; then
    my_ipv4_if=$2
else
    my_ipv4_if=$DEFAULT_IPV4_IF
fi

# gets our primary IPv4 address
my_ipv4_addr=`ip -4 addr show dev $my_ipv4_if primary \
                 | perl -ne 'print $1 if /^\ *inet (\d+(?:\.\d+){3})/'`

# builds an IPv6 prefix from our IPv4 address
# (from http://tldp.org/HOWTO/Linux+IPv6-HOWTO/ section 9.4.1)
my_ipv6_prefix=`printf "2002:%02x%02x:%02x%02x" \
                       \`echo $my_ipv4_addr | tr "." " "\``


function ipv6_up {

    # ensures the ipv6 kernel module is loaded
    modprobe ipv6

    # sets up 6to4 tunnel
    # (from http://tldp.org/HOWTO/Linux+IPv6-HOWTO/ section 9.4.1.1)
    ip tunnel add tun6to4 mode sit ttl 64 remote any local $my_ipv4_addr
    ip link set dev tun6to4 up
    ip -6 addr add ${my_ipv6_prefix}::1/16 dev tun6to4
    ip -6 route add 2000::/3 via ::192.88.99.1 dev tun6to4 metric 1
    ip -6 addr add ${my_ipv6_prefix}::1/128 dev $my_ipv4_if

    # add any extra setup configuration here:
    #ip -6 route add ${my_ipv6_prefix}:f00d::/64 dev eth1 proto static
}


function ipv6_down {

    # add any extra take-down configuration here:
    #ip -6 route del ${my_ipv6_prefix}:f00d::/64 dev eth1 proto static

    # brings down 6to4 tunnel
    # (from http://tldp.org/HOWTO/Linux+IPv6-HOWTO/ section 9.4.2.1)
    ip -6 addr del ${my_ipv6_prefix}::1/128 dev $my_ipv4_if
    ip -6 route flush dev tun6to4
    ip -6 addr del ${my_ipv6_prefix}::1/16 dev tun6to4
    ip link set dev tun6to4 down
    ip tunnel del tun6to4
}


case "$1" in
  up)
        ipv6_up
	;;
  down)
        ipv6_down
	;;
  start)
	echo -n "Starting $DESC: $NAME"
        ipv6_up
	echo "."
	;;
  stop)
	echo -n "Stopping $DESC: $NAME "
        ipv6_down
	echo "."
	;;
  restart|force-reload)
	echo -n "Restarting $DESC: $NAME"
        ipv6_down
	sleep 1
        ipv6_up
	echo "."
	;;
  *)
	N=/etc/init.d/$NAME
	# echo "Usage: $N {start|stop|restart|reload|force-reload}" >&2
	echo "Usage: $N {start|stop|restart|force-reload} [ipv4-iface]" >&2
	exit 1
	;;
esac

exit 0