Swisscom 6rd script for DD-WRT 2.6 kernel

swisscom-6rd.wanup

#!/bin/sh
# This adds the appropriate 6rd tunnel for Swisscom users with a DD-WRT based router.
# Script forked from
# https://gist.github.com/VictorLowther/2969270
# using info from
# http://vincent.bernat.im/en/blog/2014-swisscom-router.html
# Get it copied to /tmp/etc/config/(whatever).wanup, 
# The following is relevant for PPP, not sure it is for DHCP
# and then ln -s /tmp/etc/config/(whatever).ipup to it.

# The Swisscom customer 6rd gateway.
REMOTE=193.5.29.1

# Your local IP address.
LOCAL="$(nvram get wan_ipaddr)"

# Your local IP address as a Swisscom specific 6rd prefix.
# With Swisscom's prefix length of 28 bits and 32 bits of IP subnet is only 4 bits.
# SUBNET's value is [0..15]
SUBNET=1
V6PREFIX="$(printf '%02X%02X%02X%02X%X' $(echo $LOCAL $SUBNET | tr '.' ' ') | awk '{print "2a02:120" substr($1,1,1) ":" substr($1,2,4) ":" substr($1,6,7) }')"

# The local address that will wind up assigned to your bridge
V6LOCAL=$V6PREFIX::1/64

# The remote address bound to the sit tunnel to the 6rd gateway
V6REMOTE=$V6PREFIX::2/28

# The name of the tunnel
TUNNEL=6rd

# The MTU of the tunnel. See references
MTU=1472

# Make sure we have needed kernel modules
insmod ipv6
insmod sit
# Stock modules are too old for proper firewall operations.
# These were found from http://www.dd-wrt.com/phpBB2/viewtopic.php?p=732628
insmod /opt/home/root/ip6tables.ko
insmod /opt/home/root/ip6_tables.ko
insmod /opt/home/root/ip6table_filter.ko
insmod /opt/home/root/ip6t_rt.ko
insmod /opt/home/root/nf_conntrack_ipv6.ko

# Set up the IPv6 firewall
ip6tables-restore < /opt/etc/ip6tables.rules

# Clean up any leftovers.  This ensures we start with a fresh tunnel the script is starting.
killall radvd
ip -6 addr flush dev br0 scope global
ip -6 addr flush dev $TUNNEL scope global
ip -6 route flush dev br0
ip -6 route flush dev $TUNNEL
ip link set $TUNNEL down
ip tunnel del $TUNNEL

# Create our tunnel.
ip tunnel add $TUNNEL mode sit remote $REMOTE local $LOCAL ttl 64
ip link set $TUNNEL up
ip link set mtu $MTU dev $TUNNEL
ip addr add $V6REMOTE dev $TUNNEL
ip addr add $V6LOCAL dev br0
ip route add ::/0 dev $TUNNEL

# Make sure we forward IPv6 packets
echo 1 > /proc/sys/net/ipv6/conf/all/forwarding

# Create an RADVD config file and start radvd to let everyone on our local network get an auto-assigned IP6 address.
cat >/tmp/radvd.conf <<EOF 
interface br0 {
  AdvLinkMTU $MTU; 
  AdvSendAdvert on;
  prefix $V6PREFIX::/64 { 
    AdvOnLink on; 
    AdvAutonomous on;
    AdvRouterAddr on;
  }; 
};
EOF

radvd -C /tmp/radvd.conf