IPv6#

Network → IPv6, at /ipv6. Four tabs: Status, what the router holds; and three that edit the configuration — Addressing, Router advertisements and Prefix delegation. Every form adds its changes to the pending changes, applied from the Commit Bar.

Status#

Tile	What it counts
Routable addresses	global and unique-local addresses. Link-local ones are left out: every interface that is up has one whether or not IPv6 works. Link-local only when that is all there is
Routes	rows in the IPv6 forwarding table
Default route	where `::/0` goes, or Discarded or Rejected for one that drops its traffic
IPv6 firewall rule sets	IPv6 rule sets in the firewall. 0 says IPv6 traffic is not filtered: the firewall's state policy alone is not a rule set

Below them: every IPv6 address the interfaces hold, with its scope (Global, Unique local, Link-local); the IPv6 forwarding table, as on Static routes; the neighbour table; and the IPv6 firewall's counters. The loopback's addresses and routes are not listed.

A read that fails is named at the top and its panel says Not read: an empty neighbour table and one the router would not print are different facts. If the forwarding table itself cannot be read, the tab says so and shows nothing else.

Addressing#

One row per interface with any IPv6 configuration: its static addresses, whether it takes an address by DHCPv6 and by SLAAC, and its EUI-64 prefixes. Add IPv6 to an interface, or a row, opens the interface's form:

Field	What it takes
Addresses	static IPv6 addresses with their prefix length, such as `2001:db8:1::1/64`
Address from DHCPv6	the interface asks a DHCPv6 server for an address — usually the WAN
Address from SLAAC	the interface forms an address from the router advertisements it receives
EUI-64 addresses	/64 networks in each of which the interface forms an address from its MAC address

Remove IPv6 settings, pressed twice, removes all four from the interface. Its link-local address stays: the kernel gives every interface one.

Router advertisements#

Devices on a network learn its IPv6 prefix, their gateway and their DNS servers from the router advertisements the router sends there. One row per interface that sends them. Advertise on an interface, or a row, opens the form:

Field	What it takes
Interface	any interface, VLANs included
Prefixes	the prefixes devices form addresses from. `::/64` advertises the /64 the interface itself holds, which suits a delegated prefix that can change
DNS servers	up to three IPv6 addresses
Search domains	domains devices append to short names
Addresses from DHCPv6	devices ask a DHCPv6 server for their addresses (the M flag)
Other settings from DHCPv6	devices form their own addresses and ask DHCPv6 for settings such as DNS servers (the O flag)
Preference	the router's preference as a gateway: Low, Medium or High
Router lifetime	seconds, 4 to 9000; `0` advertises the prefixes without offering this router as a gateway
MTU	1280 to 9000 bytes, advertised to devices
Disabled	keep the settings and send nothing

With neither DHCPv6 switch on — the simplest arrangement — devices build their addresses from the prefix and use the DNS servers advertised here. Turning on Addresses from DHCPv6 without a DHCPv6 server leaves devices waiting for an address; the DHCPv6 server is on the DHCP page.

Stop advertising, pressed twice, stops the advertisements on that interface.

Prefix delegation#

A provider that delegates IPv6 prefixes hands the router a prefix, such as a /56, over DHCPv6, and the router divides it among its networks. One row per request: the interface it is made on, the length asked for, and the interfaces the prefix is divided among. Request a prefix, or a row, opens the form:

Field	What it takes
Requested on	the interface to the provider
Prefix length	32 to 64, the size to ask for. The router asks for a /64 when empty; the provider decides what it grants
Delegated to	one or more interfaces, each with a Subnet ID — which /64 of the prefix it takes, numbered from 0 — and an Interface address — `1` gives the interface `::1` in its subnet, and an EUI-64 address is used when empty

Each interface needs its own subnet ID, and the ID has to fit in the prefix: a /56 has room for 256 subnets, 0 to 255; a /60 for 16. Stop requesting, pressed twice, removes the request.

A router advertisement with prefix ::/64 on each delegated interface is what hands the delegated addresses to devices.

Advanced mode#

With Advanced mode on (Account → Preferences), the header shows the configuration path of the tab, and a Raw tab shows what the router printed for each of the Status tab's four reads.