#!/bin/bash
#
# Configures the 6to4 address based on the ip address of the interface to which
# the default route points.
# Parameter 1: action (start, stop, restart)
# 2: interface SLA (optional)
# 3: interface ID (optional)
# 4: interface prefix (optional)
# 5: IPv6 relay address (optional)
#
# Variable parameters. TUN_INTF used for start and stop, all others only start
# No validation of input at all!!
TUN_INTF=${2:-tun6to4}
SLA_INTF=${3:-0}
INTF_ID=${4:-1}
INTF_PFX=${5:-48}
TUN_RELY=${6:-192.88.99.1}
case "${1}" in
start)
# Clean up before configuring the tunnel
$0 stop ${TUN_INTF}
# IPv6 ready?
[ -f /proc/net/if_inet6 ] || exit 0
# Grab the device of the default route (may be
# multiple -> CUR_DV is an array)
CUR_DV=(`ip -4 route list | awk '/^default / { print $0 }' | \
sed 's/.* dev \([^ ]\+\).*$/\1/'`)
# Is there any device? Or no default route at all??
if [ -z ${CUR_DV} ]; then
echo "No default route. Cannot determine IPv4 address to use"
exit 0
fi
# We simply take the device from the first default route
CUR_IP=(`ip -4 addr show ${CUR_DV} | awk '/inet / { print $2 }' | \
sed -e 's/^\(\([0-9]\{1,3\}\.\)\{3\}[0-9]\{1,3\}\).*$/\1/'`)
# Find the MTU on the interface used for the tunnel
DEV_MTU=`ip link show ${CUR_DV} | tr '\n' ' ' | \
sed 's/.* mtu \([0-9]\+\).*$/\1/'`
# Multiple IP addresses may be defined on device. First one is ours.
# Add the tunnel. The local address is the one found from default route.
ip tunnel add ${TUN_INTF} mode sit remote any local ${CUR_IP}
# Bring the tunnel up.
ip link set dev ${TUN_INTF} mtu `expr ${DEV_MTU} - 20` up
# Add the interface address
IPV6_ADDR=$(printf "2002:%02x%02x:%02x%02x:%04x::%04x" \
$(echo "${CUR_IP} ${SLA_INTF} ${INTF_ID}" | tr '.' ' '))
ip -6 addr add ${IPV6_ADDR}/${INTF_PFX} dev ${TUN_INTF}
# Add the routes
ip -6 route add 2002::/16 dev ${TUN_INTF}
ip -6 route add ::/0 via ::${TUN_RELY} dev ${TUN_INTF} metric 1
# Notify
echo "6to4 tunnel '${TUN_INTF}' created." \
"IPv6 address: ${IPV6_ADDR}/${INTF_PFX}, IPv6 relay: ${TUN_RELY}"
;;
stop)
# Skip if device is not configured
ip link list ${TUN_INTF} > /dev/null 2>&1
if [ $? = 0 ]; then
# Remove all routes going through this device
ip -6 route flush dev ${TUN_INTF}
# Disable the link
ip link set dev ${TUN_INTF} down
# Delete the device
ip tunnel del ${TUN_INTF}
# Notify
echo "6to4 tunnel '${TUN_INTF}' removed."
fi
;;
restart)
$0 stop ${2}
$0 start ${2} ${3} ${4} ${5}
;;
*)
echo "Usage: `basename $0` (start|restart)" \
"[<tunnel-name> [<sla> [<int-id> [<prefix> [<relay-ip>]]]]]"
echo " `basename $0` stop [<tunnel-name>]"
;;
esac
