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Prep for Tomorrow with an IPv6 Testbed - Page 2

 By Carla Schroder
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Problems

The number one problem is them bad firewalls blocking your nice IPv6-over-IPv4 packets. Make sure port 41 is open, both incoming and outgoing. Problem number two is not having support in the kernel.

Building Your IPv6 Subnet

Now you can make your IPv6-enabled box into a nice IPv6 gateway for other hosts on your LAN. Go back into tspc.conf and add or uncomment these lines: 

host_type=router
prefixlen=48
if_prefix=eth0

Then killall tspc, and re-run ./tspc, so that it will read the new configuration.

Now you'll need radvd, the Router ADVertisement Daemon, to tell your other hosts where their shiny new IPv6 gateway is. Here is what /etc/radvd.conf should look like: 

interface eth0
{
   AdvSendAdvert on;
   prefix fe80::20a:e4ff:fe40:/64
   {
      AdvOnLink on;
      AdvAutonomous on;
   };
};

The prefix address is the IPv6 address assigned to eth0, minus the host part of the address: 

$ /sbin/ifconfig
eth0
...
inet6 addr: 2001:5c0:80fd::fffe::1/64 Scope:Global
inet6 addr: fe80::20a:e4ff:fe40:8bfd/64 Scope:Link

Notice how eth0 has been assigned two addresses. IPv6 lets you directly assign multiple addresses to a NIC, without futzing with aliases. You want the Scope:Link address, because this defines your local pool of addresses.

Now when you run /sbin/ifconfig on your other hosts, they should display their brand-new IPv6 addresses, and you should be able to view the dancing turtle.

The Linux IPv6 Howto, by Peter Bieringer, is the ultimate HOWTO, start with it. Security implications are largely unknown at this point, so it's best to test this on a little test network, and not with your real-life production machines.

Resources

This article was originally published on Sep 22, 2004
cschroder@internet.com
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