Month: November 2010

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

#!/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 ::192.88.99.1 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;
};
};
EOF
}

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

4. 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 192.88.99.1, not just Comcast.

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

I’m an openwrt novice, but I know enough about linux and iptables to usually get done what I want. When Comcast announced they were trialing IPv6, I jumped at the opportunity to migration from my trusty Hurricane Electric tunnel to something more direct.

I’m running Kamikaze 8.09.1 brcm-2.4 on my Linksys WRT54GL these instructions probably won’t work elsewhere. I’m guessing that IPv6 is a little different in a 2.6 kernel with a new iptables. If you have very new stuff you should be using 6rd instead of 6to4.

I’m writing this because much of the information I found out there for 6to4 on Linux didn’t work for me, or was only partly correct and I had to piece together suggestions from different sources.

make a script in /etc/rc.d with this content. I called mine comcast6to4

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`
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 ::192.88.99.1 dev c6to4

Make your /etc/radvd.conf look like this:

interface br-lan
{
AdvSendAdvert on;
MinRtrAdvInterval 3;
MaxRtrAdvInterval 10;
prefix $local6prefix:1::/64
{
AdvOnLink on;
AdvAutonomous on;
AdvRouterAddr on;
AdvValidLifetime 86400;
AdvPreferredLifetime 86400;
};
};

That is it. I’m not going to explain it. Read the links below for all of that.

Sorry this isn’t a complete solution. You’ll have to fill in that $local6prefix in radvd.conf yourself.

Works Cited:

http://www.reddit.com/r/linux/comments/dbobx/

http://www.comcast6.net/

http://wiki.debian.org/DebianIPv6#IPv66to4Configuration

http://tldp.org/HOWTO/Linux+IPv6-HOWTO/configuring-ipv6to4-tunnels.html

http://en.wikipedia.org/wiki/6to4

http://www.dslreports.com/forum/r24972279-IPv6-via-6in4

http://www.anyweb.co.nz/tutorial/v6Linux6to4