OpenWRT 10.03.1-rc2 and Comcast IPv6

After documenting the IPv6 goodness for the old kamikaze release of openwrt, I wanted to play with something a little newer. I also wanted newer iptables so I could play with the tee module.

Some notes:

  • Still no 6rd support on OpenWRT AFAIK
  • rc2 and rc3 are the same for the brcm-2.4 version of Openwrt 10.03.1
  • brcm4700 doesn’t work well at all with my WRT54GL. I think the open source broadcom drivers still aren’t as stable as the proprietary ones that ship with 2.4
  • nearly the same config scripts as the old kamikaze work

Once you flash the router with the firmware you will need to install some extra packages.

  1. opkg update
  2. opkg install ip kmod-ipv6 kmod-sit radvd
  3. paste this code into a new startup script at /etc/init.d/comcast6to4
  4. #!/bin/sh /etc/rc.common

    inetip=`ip -4 addr show dev eth0.1 | awk ‘/inet / {print $2}’ | cut -d/ -f 1`
    inetipspaced=`echo $inetip | tr . ‘ ‘`
    local6prefix=`printf 2002:%02x%02x:%02x%02x $inetipspaced`

    start() {
    ip tunnel add c6to4 mode sit ttl 255 remote any local $inetip
    ip link set c6to4 up
    ip -6 addr add $local6prefix:0::1/64 dev c6to4
    ip -6 addr add $local6prefix:1::1/64 dev br-lan
    ip -6 route add 2000::/3 via :: dev c6to4
    sysctl -w net.ipv6.conf.all.forwarding=1 > /dev/null
    cat > /etc/radvd.conf <<EOF
    interface br-lan
    AdvSendAdvert on;
    MinRtrAdvInterval 3;
    MaxRtrAdvInterval 10;
    prefix $local6prefix:1::/64
    AdvOnLink on;
    AdvAutonomous on;
    AdvRouterAddr on;
    AdvValidLifetime 86400;
    AdvPreferredLifetime 86400;

    stop() {
      ip tunnel del c6to4
      ip -6 addr del $local6prefix:1::1/64 dev br-lan

  5. pushd /etc/rc.d ; ln –s ../init.d/comcast6to4 S42comcast6to4

Then be glad you have ipv6.


This will actually work for ANY provider which uses the standard IPv6 6to4 address of, not just Comcast.

Now if only Comcast would open back up their trial so I could join my work to the ipv6 network.

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