- I’m never going to remember MACs
- Even when IPs are carefully thought out, if something happens to the DHCP server and it needs to be rebuilt, IP no longer tells you anything about what device it is
Whereas hostname/DHCP client name shows up in almost every router UI, is viewable from any *nix machine on the network (when DHCP and DNS work together), and is typically a first-class citizen in the DHCP lease settings themselves. Super handy. As a side bonus: rogue hostnames are immediately obvious, but rogue MACs or IPs require investigation before you know whether they are benign.
The point GP had that it won't work, then DHCPv6 is not used.
I believe there is another way, but the router has to support it and I forget what it's called.
Configure your ntp clients to use the name, and maybe add a pool.ntp.org entry or two into your configs.
So how do you do this hands-off, ie without manually changing things on the clients, without DHCPv6?
There are options for IPv6: PFSense, as an example, has "Assisted" RA mode where devices can use SLAAC or DHCPv6, so you have SLAAC for general clients that don't need more (e.g: phones that don't support DHCPv6), but clients that want more can use DHCP to provide specific reserved addresses and DNS names, etc...
I ended up with bind and rfc2136 dynamic updates. Not all devices are capable of doing it, but it is what Active Directory does by default.
The main hold out against DHCPv6 is Android:
Complains by them? Won't fix (Intended behavior)
It's not a dichotomy between DHCPv6 and SLAAC. You can hard-coded addresses too. Since it's your homelab you presumably already know all the devices that will be connected. It's what I do.
You may not even need to hard-code the prefix everywhere. Eg with systemd-networkd you can configure the device as:
[Network]
IPv6AcceptRA=yes
[IPv6AcceptRA]
Token=static:::1:2:3:4
>My question then is: is there some standard for the DNS server on the router to somehow know the v6 IPs of the hosts on the network
NDP discovery (`ip -6 neigh show`) will let you know about other IPs (and corresponding MAC addresses) on the link. It won't do anything for matching them up to DNS names.
Stateful DHCPv6 is the bad one. It assigns hosts specific addresses.
> the router essentially always knows the MAC address, IP address and hostname of each device.
You can still have this with ipv6 addresses. They easiest way is to use eui64, the original ipv6 addressing scheme where the address is calculated from the subnet + the MAC address of the interface. That way server VMs get deterministic addresses. If you use network-manager you can configure eui64 with the "add-gen-mode=eui64" setting.
In my homelab, I have a few server VMs that use eui64 addressing whereas the end user devices use privacy addresses randomly selected from the subnet.
RFC6106 ? You're right that works. I was just trying to communicate the unobjectionable nature of stateless DHCPv6.
Stateful DHCPv6 is bad because it undermines the concept of hosts selecting their own addresses as needed for privacy, tethering, etc.
The decade old Android issue where Google refuses to implement stateful DCHPv6 provides some good background: https://issuetracker.google.com/issues/36949085#comment53
Let's say I have a very small home lab. I have a handful of hosts that get their IP addresses via DHCP from my router. In the router, DHCP and DNS are tightly coupled such that the router essentially always knows the IP address and and hostname.
Now I want to run IPv6 on this network as a first-class citizen. Since DHCPv6 is apparently frowned upon by v6 purists, and not all devices on my network support it, that leaves SLAAC. My understanding of SLAAC is that each node essentially picks its own globally unique IP instead of asking a router for the IP. My question then is: is there some standard for the DNS server on the router to somehow know the v6 IPs of the hosts on the network so that it can automatically create the right A records?