Describe FreeBSD 6to4 konfiguráció here. Details of the example configuration =====================================

The example below is assuming that the public IPv4 address in the WAN interface of the BSD is 192.1.2.3. You should replace that with the right information for your own case, same with other data used in the example.

Also, you need to understand how to calculate the 6to4 IPv6 address for your router. This is done using the IPv4 address and the IPv6 6to4 prefix.

The 6to4 prefix 2002::/16 is taking the first (high order) 16 bits. Then the bits 17 to 48 are the nibble notation of the IPv4 address. So in our example it will be:

192 = c0 1 = 01 2 = 02 3 = 03

So consequently: 2002:c001:0203::/48

We will use the first address of the prefix for the WAN interface, so 2002:c001:0203::1/128

Also, the anycast address for 6to4 is: 192.88.99.1

In the text below, both, the generic commands and example data is used.

A) Configure 6to4 tunneling ============================

Create an stf interface (in case it doesn't exist):

• # ifconfig stf create By default the stf interface is not enabled.

Add local 6to4 address to interface (note: prefix length 16 is very important!)

• # ifconfig stf0 inet6 6to4addr prefixlen 16 # ifconfig stf0 inet6 2002:c001:0203::1 prefixlen 16

Configure IPv6 connectivity ================================

Because we are configuring a 6to4 relay it should have IPv6 connectivity (either native or via a tunnel) through an IPv6 gateway (for our example we use 2001:7f9:1::1 as GW address). After having configured an IPv6 address on the corresponding interface, the default route should be configured:

If our IPv6 interface is interface ne0:

To configure the IPv6 address:

• # ifconfig ne0 inet6 alias 2001:7f9:1::2

To add a default route:

• # route add -inet6 default 2001:7f9:1::1

C) Configure prefix advertisements ===================================

Somewhere on the Relay network, the device in charge of announcing prefixes (typically a BGP router) should announce 2002::/16 prefix to its IPv6 peerings.

This would allow native IPv6 nodes to reach 6to4 nodes (2002::/16 addresses).

Regarding the IPv4 reachability of the Relay there are two options:

1) Configure the 6to4 anycast IPv4 address (192.88.99.1) and announce the anycast prefix (192.88.99.0/24) to the site IPv4 peerings.

2) Use another public IPv4 address.

If 1) is chosen 6to4 hosts will be able to find it automatically, with no need for any manual configuration.

In case of choosing 2) some kind of advertisement of the IPv4 address is needed (usually a FQDN-Fully Qualified Domain Name) in order to allow others to configure our relay.

This will allow 6to4 nodes (2002::/16 addresses) to reach native IPv6 nodes through our relay.

D) Making your configuration persistent ========================================

In order to make your configuration persistent a script could be used to be executed at boot time. The idea is to have an script that executes all the commands you need to configure everything as desired.

An example follows, it takes as argument the local host public IPv4 address:

• #!/bin/sh IPV4=$1

  PARTS=echo $IPV4 | tr . ' ' PREFIX48=printf "2002:%02x%02x:%02x%02x" $PARTS STF_IF="stf0" STF_NET6="$PREFIX48":0000 STF_IP6="$STF_NET6"::1 ifconfig $STF_IF inet6 $STF_IP6 prefixlen 16 alias ifconfig ne0 inet6 alias 2001:7f9:1::2 route add -inet6 default 2001:7f9:1::1

For FreeBSD:

• Set in /etc/rc.conf: stf_interface_ipv4addr="public_v4addr" ipv6_defaultrouter="2001:7f9:1::1"

Configuration examples may vary for other BSD distributions.

Annex A: Remove a 6to4 tunnel using "ip" and a dedicated tunnel device =======================================================================

Remove a 6to4 interface address

• # ifconfig stf0 inet6 -alias 2002:c001:0203::1

Remove 6to4 prefix route

• First we can see the route table with:
  • # netstat -rn

  Now we can delete the route entry for 2002::/16 prefix via <gateway_IPv6>

with:

• # route delete -inet6 2002::/16 <gateway_IPv6>