.\"	$OpenBSD: dhcp6leased.conf.5,v 1.4 2024/11/01 08:27:49 kn Exp $
.\"
.\" Copyright (c) 2018, 2021, 2024 Florian Obser <florian@openbsd.org>
.\" Copyright (c) 2005 Esben Norby <norby@openbsd.org>
.\" Copyright (c) 2004 Claudio Jeker <claudio@openbsd.org>
.\" Copyright (c) 2003, 2004 Henning Brauer <henning@openbsd.org>
.\" Copyright (c) 2002 Daniel Hartmeier <dhartmei@openbsd.org>
.\"
.\" Permission to use, copy, modify, and distribute this software for any
.\" purpose with or without fee is hereby granted, provided that the above
.\" copyright notice and this permission notice appear in all copies.
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.\" THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
.\" WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
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.\"
.Dd $Mdocdate: November 1 2024 $
.Dt DHCP6LEASED.CONF 5
.Os
.Sh NAME
.Nm dhcp6leased.conf
.Nd DHCPv6 client configuration file
.Sh DESCRIPTION
The
.Xr dhcp6leased 8
daemon is a dynamic host configuration protocol client daemon for IPv6 prefix
delegation.
.Pp
The
.Nm
config file is divided into the following main sections:
.Bl -tag -width xxxx
.It Sy Macros
User-defined variables may be defined and used later, simplifying the
configuration file.
.It Sy Global Configuration
Global settings for
.Xr dhcp6leased 8 .
.It Sy Prefix delegation
.Xr dhcp6leased 8
requests prefix delegation from a DHCPv6 server and assigns prefixes
to interfaces.
This section defines on which interfaces prefix delegation should be
requested and to which interfaces prefixes should be assigned.
.El
.Sh MACROS
Macros can be defined that will later be expanded in context.
Macro names must start with a letter, digit, or underscore,
and may contain any of those characters.
Macro names may not be reserved words (for example,
.Ic interface ) .
Macros are not expanded inside quotes.
.Sh GLOBAL CONFIGURATION
These settings affect the operation of the
.Xr dhcp6leased 8
daemon as a whole.
.Bl -tag -width Ds
.It Ic request rapid commit
Send the rapid commit DHCPv6 option, requesting a two-message exchange
from the server instead of the normal four-message exchange.
.El
.Sh PREFIX DELEGATION
A list of interfaces on which to request prefix delegation:
.Bl -tag -width Ds
.It Ic request prefix delegation on Ar name Ic for Brq Ar name Ns Oo / Ns Ar prefix Oc Ar ...
.El
.Pp
This requests a prefix delegation on the upstream network interface
.Ar name
for the list of
.Ar name Ns Op / Ns Ar prefix
network interfaces.
If
.Ar prefix
is omitted a default of /64 is used.
.Pp
.Xr dhcp6leased 8
will calculate the prefix length needed to cover all interfaces in the list.
When a prefix is delegated by a DHCPv6 server,
.Xr dhcp6leased 8
splits the prefix into smaller prefixes and assigns them to the interfaces
in the order they are listed.
This might create unassigned gaps in the delegated prefix.
.Pp
For example if a /64 and /60 prefix are to be assigned to network interfaces,
.Xr dhcp6leased 8
requests a /59 prefix.
The prefix is then split into two /60 prefixes and the first /64 out of the
first /60 prefix is assigned to the first interface.
The second /60 prefix from the delegated /59 is assigned to the
second interface.
This leaves 15 unused /64 prefixes in the first /60.
.Pp
Care should be taken to avoid renumbering of existing interfaces
when new interfaces are added or existing interfaces are removed.
New interfaces can be added to the end of the list or in places
where unassigned gaps were present.
.Pp
The special name
.Cm reserve
can be used to reserve space in the delegated prefix for later use or
when an interface is removed.
.Pp
Running
.Xr dhcp6leased 8
in configtest mode with a verbosity of two or more will print the
configuration file with comments indicated how prefixes would be
assigned to network interfaces.
This can be used to check that existing interface are not renumbered.
.Pp
More than one prefix can be requested from a DHCPv6 server, however most ISP
DHCPv6 servers will only delegate a single prefix.
Therefore it is better to let
.Xr dhcp6leased 8
request a single larger prefix and split it up.
.Xr dhcp6leased 8
has a compile time limit on how many prefix requests per interface it can
handle.
.Sh FILES
.Bl -tag -width /etc/dhcp6leased.conf -compact
.It Pa /etc/dhcp6leased.conf
.Xr dhcp6leased 8
configuration file.
.El
.Sh SEE ALSO
.Xr dhcp6leasectl 8 ,
.Xr dhcp6leased 8