IPv6¶

SQMeter works on IPv6 alongside IPv4 ("dual stack"). On a network that offers IPv6 - most home routers do - the device gets IPv6 addresses of its own, and you can reach the web UI, the API, live updates and N.I.N.A. over either protocol.

IPv4 always keeps working. A network without IPv4 (IPv6-only) isn't supported yet.

Turning it on or off¶

Settings → Network → WiFi → IPv6 (on by default). It applies after a restart. With it off, the device behaves exactly as an IPv4-only device: no IPv6 addresses, nothing advertised over IPv6.

Turn it off if IPv6 on your network misbehaves, or you simply don't want it.

The device's addresses¶

System → WiFi lists each IPv6 address with its kind:

Shown as	Address	Meaning
link-local	`fe80::...`	Always present while IPv6 is on. Works on the local network only; your computer may need the interface (`fe80::...%en0`).
local	`fd..::...`	A unique-local address, when your router hands out a private IPv6 prefix.
global	`2a02:...`, `2001:...`	A normal IPv6 address from your internet provider's prefix.

The device picks these up by itself (SLAAC) from your router's announcements; there's nothing to configure. When the provider changes the prefix the device follows. The same list is in GET /api/status as wifi.ipv6.

Reaching the device over IPv6¶

By name: with mDNS on, http://sqmeter.local answers with both the IPv4 and the IPv6 addresses (A and AAAA records), so your computer can use either.
By address: put IPv6 addresses in brackets in a browser or URL - http://[2a02:8010:abcd:1::9]/. From a terminal: curl -g "http://[2a02:8010:abcd:1::9]/api/status".
N.I.N.A. / Alpaca: discovery also answers on the Alpaca IPv6 discovery group (ff12::a1:2345, port 32227), so clients that discover over IPv6 find the device too.

flowchart LR
    accTitle: Who can reach SQMeter over IPv6
    accDescr: Requests over IPv6 are accepted from link-local addresses and from the device's own network prefixes; anything else gets 403. IPv4 is unchanged.
    REQ["Request over IPv6"] --> LL{"From fe80::/10<br/>(link-local)?"}
    LL -->|yes| OK["Served"]
    LL -->|no| PREFIX{"Same /64 prefix as<br/>one of the device's addresses?"}
    PREFIX -->|yes| OK
    PREFIX -->|no| NO["403 - only the<br/>local network"]

Who can reach SQMeter over IPv6: link-local and the device's own prefixes, nobody else.

Diagram in words

A request that arrives over IPv6 is served if it comes from a link-local address (fe80::/10), or from an address with the same /64 prefix as one of the device's own addresses. Anything else gets 403. Requests over IPv4 aren't affected.

Only from your local network¶

A global IPv6 address is, in principle, reachable from the internet if the router allows it. So over IPv6 the device only accepts requests from link-local addresses and from addresses in its own network prefixes; anything else gets 403 IPv6 requests are only accepted from the local network. That covers the web UI, the API, WebSockets and Alpaca; Alpaca discovery over IPv6 only answers the same local addresses. IPv4 is unchanged.

This is a backstop, not a reason to expose the device: it still has no TLS, so keep it behind your router's firewall and use a VPN for remote access (Security).

Outbound connections¶

Service	Over IPv6
MQTT broker	Yes - an IPv6 address (`fd00::10`, or `[fd00::10]:1883` to give the port there) or a name that only has an IPv6 address
Webhook (`http://`)	Yes - `http://[fd00::10]:8080/hook` or a name that only has an IPv6 address
Webhook (`https://`), Pushover, ntfy, GitHub update checks, NTP	IPv4 for now

Names with both kinds of address are reached over IPv4, so a broken IPv6 connection upstream never delays MQTT, alerts or updates. The secure (https) clients on the current firmware platform only speak IPv4; they move to IPv6 with a later platform upgrade. All of those services are reachable over IPv4 today, so nothing stops working.

Settings check IPv6 addresses the same way in the browser and on the device:

You type	Result
`fd00::10` or `[fd00::10]`	IPv6 broker on the Port field's port
`[fd00::10]:1883`	IPv6 broker on port 1883
`broker.local:1883`	"Put the port in the Port field"
`fe80::1%wlan0`	"Leave out the %zone - the device has one network interface"
`https://[fd00::10]/hook`	"https to an IPv6 address isn't supported yet - use a host name, or http"

The setup hotspot¶

The SQM-Setup hotspot stays IPv4-only - phones join it with IPv4. IPv6 starts once the device is on your network.