.\"	$OpenBSD: unwind.conf.5,v 1.25 2020/12/26 19:05:13 kn Exp $
.\"
.\" Copyright (c) 2018 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.
.\"
.\" THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
.\" WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
.\" MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
.\" ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
.\" WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
.\" ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
.\" OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
.\"
.Dd $Mdocdate: December 26 2020 $
.Dt UNWIND.CONF 5
.Os
.Sh NAME
.Nm unwind.conf
.Nd validating DNS resolver configuration file
.Sh DESCRIPTION
The
.Xr unwind 8
daemon is a validating DNS resolver.
.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 unwind 8 .
.El
.Pp
Additional configuration files can be included with the
.Ic include
keyword.
.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 forwarder ,
.Ic port ,
or
.Ic DoT ) .
Macros are not expanded inside quotes.
.Pp
For example:
.Bd -literal -offset indent
fwd1=192.0.2.53
fwd2=192.0.2.153
forwarder { $fwd1 $fwd2 }
.Ed
.Sh GLOBAL CONFIGURATION
.Bl -tag -width Ds
.It Ic block list Ar file Op Cm log
A file containing domains to block, one per line.
If a domain from this list is queried
.Nm unwind
answers with a return code of
.Cm refused .
With
.Cm log
blocked queries are logged.
.It Ic forwarder Brq Ar address Oo Ic port Ar number Oc Oo Oo Ic authentication name Ar name Oc Ic DoT Oc ...
A list of addresses of DNS name servers to forward queries to.
.Ic port
defaults to 53.
If
.Ic DoT
is specified, use DNS over TLS when sending queries to the server at
.Ar address .
The default
.Ic port
is 853.
.Ar name
validates the certificate of the DNS over TLS server.
.It Ic preference Brq Ar type ...
A list of DNS name server types to specify the order in which
name servers are picked when measured round-trip time medians are equal.
Additionally, the first mentioned type gets a time bonus.
Validating name servers are always picked over non-validating name servers.
DNS name server types are:
.Pp
.Bl -tag -width "forwarder" -compact
.It Ic stub
Name servers learned via DHCP, queried using the libc functions.
See
.Xr asr_run 3 .
Will never validate.
Useful when running behind broken middle boxes that do not like edns0.
DNS answers from stub name servers are not cached.
.It Ic dhcp
Name servers learned via DHCP or SLAAC.
.It Ic oDoT-dhcp
Name servers learned via DHCP or SLAAC.
.Nm unwind
tries to opportunistically use DNS over TLS.
.It Ic DoT
DNS over TLS name servers configured in
.Nm .
.It Ic forwarder
Name servers configured in
.Nm .
.It Ic oDoT-forwarder
Name servers configured in
.Nm .
.Nm unwind
tries to opportunistically use DNS over TLS.
.It Ic recursor
.Nm unwind
itself recursively resolves names.
.El
.Pp
The default preference is
.Ic DoT oDoT-forwarder forwarder recursor oDoT-dhcp dhcp stub .
.It Ic force Oo Cm accept bogus Oc Ar type Brq Ar name ...
Force resolving of
.Ar name
and its subdomains by the given resolver
.Ar type .
If
.Cm accept bogus
is specified validation is not enforced.
.El
.Sh FILES
.Bl -tag -width "/etc/unwind.conf" -compact
.It Pa /etc/unwind.conf
The default
.Xr unwind 8
configuration file.
.El
.Sh SEE ALSO
.Xr rc.conf.local 8 ,
.Xr unwind 8 ,
.Xr unwindctl 8
.Sh HISTORY
The
.Nm
file format first appeared in
.Ox 6.5 .