Call for Contributions
This section needs improvements, examples and explanations.
Please take a look at the Contributing Guide for our Documentation.
NPTv6
NPTv6 is a form of NAT for IPv6. It’s described in RFC 6296.
Usage
NPTv6 is very useful for IPv6 multihoming. It is also commonly used when the external IPv6 prefix is dynamic, as it prevents the need for renumbering of internal hosts when the extern prefix changes.
Let’s assume the following network configuration:
eth0 : LAN
eth1 : WAN1, with 2001:db8:e1::/48 routed towards it
eth2 : WAN2, with 2001:db8:e2::/48 routed towards it
Regarding LAN hosts addressing, why would you choose 2001:db8:e1::/48 over 2001:db8:e2::/48? What happens when you get a new provider with a different routed IPv6 subnet?
The solution here is to assign to your hosts ULAs and to prefix-translate their address to the right subnet when going through your router.
LAN Subnet : fc00:dead:beef::/48
WAN 1 Subnet : 2001:db8:e1::/48
WAN 2 Subnet : 2001:db8:e2::/48
eth0 addr : fc00:dead:beef::1/48
eth1 addr : 2001:db8:e1::1/48
eth2 addr : 2001:db8:e2::1/48
VyOS Support
NPTv6 support has been added in VyOS 1.2 (Crux) and is available through nat nptv6 configuration nodes.
set nat nptv6 rule 10 source prefix 'fc00:dead:beef::/48'
set nat nptv6 rule 10 outbound-interface 'eth1'
set nat nptv6 rule 10 translation prefix '2001:db8:e1::/48'
set nat nptv6 rule 20 source prefix 'fc00:dead:beef::/48'
set nat nptv6 rule 20 outbound-interface 'eth2'
set nat nptv6 rule 20 translation prefix '2001:db8:e2::/48'
Resulting in the following ip6tables rules:
Chain VYOS_DNPT_HOOK (1 references)
pkts bytes target prot opt in out source destination
0 0 NETMAP all eth1 any anywhere 2001:db8:e1::/48 to:fc00:dead:beef::/48
0 0 NETMAP all eth2 any anywhere 2001:db8:e2::/48 to:fc00:dead:beef::/48
0 0 RETURN all any any anywhere anywhere
Chain VYOS_SNPT_HOOK (1 references)
pkts bytes target prot opt in out source destination
0 0 NETMAP all any eth1 fc00:dead:beef::/48 anywhere to:2001:db8:e1::/48
0 0 NETMAP all any eth2 fc00:dead:beef::/48 anywhere to:2001:db8:e2::/48
0 0 RETURN all any any anywhere anywhere