OPNsense Forum

English Forums => 24.7, 24.10 Legacy Series => Topic started by: OpenMind on January 23, 2025, 02:07:11 PM

Title: IPv6 ULA for LAN Setup
Post by: OpenMind on January 23, 2025, 02:07:11 PM
Hi,

I'm playing a bit around and want to test some things with ULA here, but I struggle to set up an IPv6 LAN, without having a WAN IPv6 populated to the LAN.

I did not find any guide for this, or am I just blind?

Can you help me to set this up, please?
Title: Re: IPv6 ULA for LAN Setup
Post by: OpenMind on January 23, 2025, 03:53:30 PM
Let me update this with further Infos.

WAN IPv4 only.
LAN should be using IPv4 and IPv6. IPv4 is working as expected. I want to make sure clients on the LAN can communicate using a ULA IPv6 Address.
Title: Re: IPv6 ULA for LAN Setup
Post by: meyergru on January 23, 2025, 04:24:32 PM
Then choose any valid ULA prefix, set the IPv6 address of your LAN to an IPv6 address within that prefix (e.g. use the EUI-64 as suffix), under "Services: Router Advertisements: [LAN]" set the DNS server address and the default gateway address to the same address as the interface, check "Advertise default gateway" (not for internet access, but probably to reach other subnets). "Router Advertisements" should be set to "Unmanaged", unless you want to use DHCPv6, which does not work for many devices anyway.

Any device that can handle SLAAC will then get a ULA from your range and they should be able to communicate with one another.
Title: Re: IPv6 ULA for LAN Setup
Post by: OpenMind on January 23, 2025, 07:13:42 PM
Hi, thanks, this seems to work. I was fiddling around with the DHCP, but this is much easier.
Title: Re: IPv6 ULA for LAN Setup
Post by: meyergru on January 23, 2025, 09:07:13 PM
As I said: Use SLAAC, not DHCPv6. Other than that, this might come in handy if you experience problems:

https://en.wikipedia.org/wiki/Comparison_of_IPv6_support_in_operating_systems

At least, with ULA addressing, you can get (limited) LAN support even for DNS (see this (https://forum.opnsense.org/index.php?topic=45333)) to see what I mean.