.. _nat66:

############
NAT66(NPTv6)
############

:abbr:`NPTv6 (IPv6-to-IPv6 Network Prefix Translation)` is an address 
translation technology based on IPv6 networks, used to convert an IPv6 
address prefix in an IPv6 message into another IPv6 address prefix. 
We call this address translation method NAT66. Devices that support the NAT66
function are called NAT66 devices, which can provide NAT66 source
and destination address translation functions.

Overview
========

Different NAT Types
-------------------

.. _source-nat66:

SNAT66
^^^^^^

:abbr:`SNPTv6 (Source IPv6-to-IPv6 Network Prefix Translation)` The conversion
function is mainly used in the following scenarios:

* A single internal network and external network. Use the NAT66 device to 
  connect a single internal network and public network, and the hosts in 
  the internal network use IPv6 address prefixes that only support 
  routing within the local range. When a host in the internal network
  accesses the external network, the source IPv6 address prefix in 
  the message will be converted into a global unicast IPv6 address 
  prefix by the NAT66 device.
* Redundancy and load sharing. There are multiple NAT66 devices at the edge
  of an IPv6 network to another IPv6 network. The path through the NAT66 
  device to another IPv6 network forms an equivalent route, and traffic 
  can be load-shared on these NAT66 devices. In this case, you 
  can configure the same source address translation rules on these 
  NAT66 devices, so that any NAT66 device can handle IPv6 traffic between 
  different sites.
* Multi-homed. In a multi-homed network environment, the NAT66 device 
  connects to an internal network and simultaneously connects to 
  different external networks. Address translation can be configured 
  on each external network side interface of the NAT66 device to 
  convert the same internal network address into different external
  network addresses, and realize the mapping of the same internal 
  address to multiple external addresses.

.. _destination-nat66:

DNAT66
^^^^^^

The :abbr:`DNPTv6 (Destination IPv6-to-IPv6 Network Prefix Translation)` 
destination address translation function is used in scenarios where the 
server in the internal network provides services to the external network,
such as providing Web services or FTP services to the external network. 
By configuring the mapping relationship between the internal server 
address and the external network address on the external network 
side interface of the NAT66 device, external network users can 
access the internal network server through the designated 
external network address.

Prefix Conversion
------------------

Source Prefix
^^^^^^^^^^^^^

Every SNAT66 rule has a translation command defined. The prefix defined
for the translation is the prefix used when the address information in
a packet is replaced.、

The :ref:`source-nat66` rule replaces the source address of the packet 
and calculates the converted address using the prefix specified in the rule.

Example:

* Convert the address prefix of a single `fc01::/64` network to `fc00::/64`
* Output from `eth0` network interface

.. code-block:: none

  set nat66 source rule 1 outbound-interface 'eth0'
  set nat66 source rule 1 source prefix 'fc01::/64'
  set nat66 source rule 1 translation address 'fc00::/64'

Destination Prefix
^^^^^^^^^^^^^^^^^^

For the :ref:`destination-nat66` rule, the destination address of
the packet isreplaced by the address calculated from the specified 
address or prefix in the `translation address` command

Example:

* Convert the address prefix of a single `fc00::/64` network 
  to `fc01::/64`
* Input from `eth0` network interface

.. code-block:: none

  set nat66 destination rule 1 inbound-interface 'eth0'
  set nat66 destination rule 1 destination address 'fc00::/64'
  set nat66 destination rule 1 translation address 'fc01::/64'

Configuration Examples
======================

Use the following topology to build a nat66 based isolated 
network between internal and external networks (dynamic prefix is 
not supported):

.. figure:: /_static/images/vyos_1_4_nat66_simple.png
   :alt: VyOS NAT66 Simple Configure

R1:

.. code-block:: none

  set interfaces ethernet eth0 ipv6 address autoconf
  set interfaces ethernet eth1 address 'fc01::1/64'
  set nat66 destination rule 1 destination address 'fc00:470:f1cd:101::/64'
  set nat66 destination rule 1 inbound-interface 'eth0'
  set nat66 destination rule 1 translation address 'fc01::/64'
  set nat66 source rule 1 outbound-interface 'eth0'
  set nat66 source rule 1 source prefix 'fc01::/64'
  set nat66 source rule 1 translation address 'fc00:470:f1cd:101::/64'

R2:

.. code-block:: none

  set interfaces bridge br1 address 'fc01::2/64'
  set interfaces bridge br1 member interface eth0
  set interfaces bridge br1 member interface eth1
  set protocols static route6 ::/0 next-hop fc01::1
  set service router-advert interface br1 prefix ::/0