Setting a static IPv6 client address

[deviantintegral]

I'm in the process of setting up a Proxmox server, which needs a static IP assigned for both IPv4 and IPv6.

In the world of IPv4, the way I've normally set it up is:

1. Set DHCP to not issue addresses in a range. For example, only assign addresses 192.168.20.51-192.168.20.254.
2. Set static IPs in that range of the first 50 addresses.

With IPv6, I obtain an address from my ISP over DHCPv6, and have the LAN interface set to track it. I get a /56 from the ISP, and it looks like a /64 is used for LAN clients. Is there anything I need to do to ensure I don't get address conflicts if I just choose a random address in that /64 range? Or does duplicate address detection handle that, and the autoconfigured LAN clients will just generate another address if needed?

I did poke around in the router advertisements settings when enabled, but didn't see anything that would obviously let me narrow the /64 to a different range to reserve other addresses.

Thanks,

[Patrick M. Hausen]

I'd recommend not to use DHCP for servers and infrastructure devices. Even with IPv4 the regular way to configure a hypervisor host is static configuration on the host.

That being sad SLAAC will generate an automatic but predictable and always identical IPv6 address as long as the MAC address of the device does not change. For the same reason you will never have an address conflict with SLAAC because your MAC addresses are guaranteed unique, already.

[deviantintegral]

Thanks, this was helpful. It turns out I was wrong about "Track Interface" using SLAAC. It actually uses DHCP (so it can set the prefix I presume). Once I figured that out, I was able to use that to infer the configuration to use and set it statically.

https://old.reddit.com/r/homelab/comments/acjzh4/ipv6_primer/ had some good bits too, in particular "you shouldn't subnet smaller than /64".