Howto IPv6 on Spectrum using OPNSense

Hey friends, I spent the last several days digging through different posts and getting half the information, so I wanted to make a short post so people know how to get IPv6 working with Spectrum, aka Time Warner Cable back in the day… for reference I am on the East Coast, so maybe that affects the network configuration as well depending on the regional ISP settings, I have seen crazier.

Anyways, lets start with the WAN:

– Set the IPv6 configuration type to DHCPv6

Next, let’s scroll all the way down to the “DHCPv6 Client Configuration” category:

– Configuration mode: Basic

– Prefix Delegation size: 56 (Overkill, but hey Spectrum allows it! If you aren’t running VLANS, you could do 64)

– Send IPv6 Prefix hint: checked (this is important, I couldn’t get IPv6 working without it)

=====End of WAN Configuration, make sure to save and apply!=========

========Begin LAN Configuration=======

First off, this will also work on any VLANs. Obviously use a different prefix though.

– IPv6 Configuration type: Track interface

Next lets scroll all the way down to the “Track IPv6 Interface” section:

– IPv6 Interface: WAN (I think this is already set by default…)

– IPv6 Prefix ID: 0 (your range is 00-ff basically, so 01,02,03, etc. look up how to count in hex if you’re unsure. I was lazy and made my VLAN number the prefix ID for each vlan, so vlan20 = prefix ID 20)

– Manual configuration: checked (this is very important, allows you to enable router advertisements)

========End LAN Configuration=======

Ok, at this point you’re 2/3 of the way there, all that we have to do next is to enable the router advertisements under Services>Router Advertisements>Name-of-your-interface. Rinse and repeat for each interface you want clients to have IPv6.

========Begin LAN Router Advertisement config=======

– Router Advertisements: Unmanaged

– Minimum interval 10

– Maximum Interval: 30

========End LAN Router Advertisement config=======

Oh just kidding, there is a fourth step. You need to allow ICMP inbound from the WAN link for IPv6. The way I am doing it might not be the best so I am open to comments, but I made a single IPv6 IN rule on the WAN link for all ICMP traffic to any destination.

EDIT: One other thing I did and I’m not sure if was necessary is I unchecked block LAN subnets on my WAN interface. The default v6 gateway is fe80: so I had suspicions that this was considered a ‘LAN’ subnet and being blocked. I’ll check this in the future and update with my findings.

Other things to consider, after this many changes a full system reboot of opnsense never hurts!