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Is there a guide somewhere about how to rig up some IPv6-to-IPv4 and IPv4-to-IPv6. I'd like to be able to run a dual stack on my home lan but not forfeit ipv4 just yet.

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How would running dual stack forfeit ipv6? –  becomingwisest Mar 20 '11 at 20:58
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Running Dual-Stack means exactly that - you're running two stacks of protocols. You will run IPv4 AND IPv6, both at the same time, neither of them being forfeited, and you won't need any IPv6-IPv4 translators, as you'll have them both natively. –  Mark Henderson Mar 20 '11 at 21:18
    
dnsmasq 6-to-4 "translation" should "just work" when dnsmasq is installed on a dual-stack box. What problem do you get? –  Bittrance Mar 20 '11 at 22:14
    
@Christopher Good point. I just meant that I didn't want to get rid of ipv4 yet (which is what a dual stack is for) –  leeand00 Mar 21 '11 at 15:44
    
@Bittrance I don't have any problems yet, I'm just taking a stab in the dark at how to go about setting a dual stack network up (I've never done that before). I've setup ipv4 networks in the past, but never an ipv6 or a dual stack network. –  leeand00 Mar 21 '11 at 15:45
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1 Answer

If the issue really is to set up an 6-to-4 router, and assuming that you can spare a Linux box as router/bridge, you want to do three things:

  1. install radvd on the LAN side of the router.
  2. setup a 6to4 tunnel to pass your IPv6 traffic over to IPv6 Internet
  3. setup firewall rules for IPv6

#PREFIX# in the below examples is the IPv6 address from the 2002: prefix reserved for legacy addresses, which can be found with "ipv6calc --ipv4_to_6to4addr ".

radvd will do router advertisements on LAN side, telling all IPv6-capable hosts how to configure their IPv6 addresses. A typical radvd.conf may look like this:

interface eth1 {  
   AdvSendAdvert on;
   MinRtrAdvInterval 30;
   MaxRtrAdvInterval 60;

   prefix 0:0:0:1::/64 {
      AdvOnLink on;
      AdvAutonomous on;
      AdvRouterAddr off;
      AdvValidLifetime 86400;
      AdvPreferredLifetime 3600;
      Base6to4Interface eth0;
   };

   RDNSS #PREFIX#:1::1 {
      AdvRDNSSOpen on;
   };
};

A 6to4 tunnel can be created thus:

ip route add 2000::/3 via ::192.88.99.1 dev sit0
ip addr  add #PREFIX#:1::1/64 dev eth1

Finally, ip6tables is your friend. The above config assumes that there is a IPv6 capable DNS server on :1::1. dnsmasq should do fine.

Hope this will be enough information to get you googling on the right howtos.

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