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.\" Copyright (c) 2007-2016 Roy Marples .\" Copyright (c) 2007-2025 Roy Marples
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.Dd November 29, 2016 .Dd June 26, 2025
.Dt RESOLVCONF 8 .Dt RESOLVCONF 8
.Os .Os
.Sh NAME .Sh NAME
.Nm resolvconf .Nm resolvconf
.Nd a framework for managing multiple DNS configurations .Nd a framework for managing multiple DNS configurations
.Sh SYNOPSIS .Sh SYNOPSIS
.Nm .Nm
.Fl I .Fl I
.Nm .Nm
.Op Fl m Ar metric .Op Fl m Ar metric
.Op Fl p .Op Fl p
.Op Fl x .Op Fl x
.Fl a Ar interface Ns Op Ar .protocol .Fl a Ar key
.No < Ns Pa file .No < Ns Pa file
.Nm .Nm
.Fl C Ar pattern
.Nm
.Fl c Ar pattern
.Nm
.Op Fl f .Op Fl f
.Fl d Ar interface Ns Op Ar .protocol .Fl d Ar key
.Nm .Nm
.Op Fl x .Op Fl x
.Fl il Ar pattern .Fl iLlp Ar pattern
.Nm .Nm
.Fl u .Fl u
.Nm .Nm
.Fl Fl version .Fl Fl version
.Sh DESCRIPTION .Sh DESCRIPTION
.Nm .Nm
manages manages
.Xr resolv.conf 5 .Xr resolv.conf 5
Show All 9 Lines
.Nm .Nm
solves this by letting the daemon send their solves this by letting the daemon send their
.Xr resolv.conf 5 .Xr resolv.conf 5
file to file to
.Nm .Nm
via via
.Xr stdin 4 .Xr stdin 4
with the argument with the argument
.Fl a Ar interface Ns Op Ar .protocol .Fl a Ar key
instead of the filesystem. instead of the filesystem.
.Nm .Nm
then updates then updates
.Pa /etc/resolv.conf .Pa /etc/resolv.conf
as it thinks best. as it thinks best.
If
.Pa /etc/resolv.conf
already exists and the top line does not match the expected signature,
then
.Nm
will refuse to update it unless the
.Fl u
update command is given.
When a local resolver other than libc is installed, such as When a local resolver other than libc is installed, such as
.Xr dnsmasq 8 .Xr dnsmasq 8
or or
.Xr named 8 , .Xr named 8 ,
then then
.Nm .Nm
will supply files that the resolver should be configured to include. will supply files that the resolver should be configured to include.
.Pp .Pp
At it's heart,
.Nm .Nm
assumes it has a job to do. is a key/value store for
In some situations .Pa resolv.conf
files.
Each entry must have a unique
.Ar key
and should be expressed as
.Sy interface.protocol
so that it's easy to tell from where the
.Pa resolv.conf
file came from.
This also allows using pattern matching such as
.Sy interface.*
to match all protocols running on the interface.
For example, a modern system will likely run DHCP, RA and DHCPv6
which could be from separate programs or one program running
many protocols.
However, this is not a fixed requirement,
.Nm .Nm
needs to act as a deterrent to writing to will work with any key name and it should be treated as an opaque value
.Pa /etc/resolv.conf . outside of
Where this file cannot be made immutable or you just need to toggle this .Nm .
behaviour,
.Nm
can be disabled by adding
.Sy resolvconf Ns = Ns NO
to
.Xr resolvconf.conf 5 .
.Pp .Pp
.Nm .Nm
can mark an interfaces can mark a
.Pa resolv.conf .Pa resolv.conf
as private. as private and optionally non-searchable.
This means that the name servers listed in that This means that the name servers listed in that
.Pa resolv.conf .Pa resolv.conf
are only used for queries against the domain/search listed in the same file. are only used for queries against the domain/search listed in the same file
and if non-searchable then the domain/search listed are
excluded from the global search list defined in
.Pa /etc/resolv.conf .
This only works when a local resolver other than libc is installed. This only works when a local resolver other than libc is installed.
See See
.Xr resolvconf.conf 5 .Xr resolvconf.conf 5
for how to configure for how to configure
.Nm .Nm
to use a local name server and how to remove the private marking. to use a local name server and how to remove the private marking.
.Pp .Pp
.Nm .Nm
can mark an interfaces can mark a
.Pa resolv.conf .Pa resolv.conf
as exclusive. as exclusive.
Only the latest exclusive interface is used for processing, otherwise all are. Only the latest exclusive key is used for processing, otherwise all are.
.Pp .Pp
When an interface goes down, it should then call When a configuration source goes away,
such as an interface going down or a VPN stopping,
it should then call
.Nm .Nm
with with
.Fl d Ar interface.* .Fl d Ar key
arguments to delete the arguments to clean up the
.Pa resolv.conf .Pa resolv.conf
file(s) for all the it added previously.
.Ar protocols For systems that support the concept of persisting configuration when
on the the source is suspended,
.Ar interface . such as the carrier going down,
then it should instead call
.Nm
with
.Fl C Ar key
arguments to deprecate the entry
.Fl c Ar key
to activate the entry when it comes back again.
This only affects the order in which the
.Pa resolv.conf
entries are processed.
.Pp .Pp
Here are some options for the above commands:- Here are some options for the above commands:
.Bl -tag -width pattern_opt .Bl -tag -width pattern_opt
.It Fl f .It Fl f
Ignore non existent interfaces. Ignore non existent
Only really useful for deleting interfaces. .Pa resolv.conf
entries.
Only really useful for deleting.
.It Fl m Ar metric .It Fl m Ar metric
Set the metric of the interface when adding it, default of 0. Set the metric of the
.Pa resolv.conf
entry when adding it, default of 0.
Lower metrics take precedence. Lower metrics take precedence.
This affects the default order of interfaces when listed. This affects the default order of entires when listed.
.It Fl p .It Fl p Op Ar pattern
Marks the interface Marks the
.Pa resolv.conf .Pa resolv.conf
as private. as private if the
.Fl a
command is given, otherwise
.Pa resolv.conf
entries having their key matching
.Ar pattern
are listed.
If an extra
.Fl p
is given then the
.Pa resolv.conf
is marked as non-searchable as well.
.It Fl x .It Fl x
Mark the interface Mark the
.Pa resolv.conf .Pa resolv.conf
as exclusive when adding, otherwise only use the latest exclusive interface. as exclusive when adding, otherwise only use the latest exclusive key.
.El .El
.Pp .Pp
.Nm .Nm
has some more commands for general usage:- has some more commands for general usage:
.Bl -tag -width pattern_opt .Bl -tag -width pattern_opt
.It Fl i Ar pattern .It Fl i Op Ar pattern
List the interfaces and protocols, optionally matching List the keys stored, optionally matching
.Ar pattern , .Ar pattern ,
we have we have
.Pa resolv.conf .Pa resolv.conf
files for. files for.
.It Fl l Ar pattern If the
.Fl L
option is given first, then the keys will be list post-processed.
.It Fl L Op Ar pattern
List the List the
.Pa resolv.conf .Pa resolv.conf
files we have,
post-processed by the
.Xr resolvconf.conf 5
configuration.
If
.Ar pattern
is specified then we list the files for the keys which match it.
.It Fl l Op Ar pattern
List the
.Pa resolv.conf
files we have. files we have.
If If
.Ar pattern .Ar pattern
is specified then we list the files for the interfaces and protocols is specified then we list the files for the keys which match it.
that match it. that match it.
.It Fl u .It Fl u
Force Force
.Nm .Nm
to update all its subscribers. to update all its subscribers.
.Nm .Nm
does not update the subscribers when adding a resolv.conf that matches does not update the subscribers when adding a resolv.conf that matches
what it already has for that interface. what it already has for that key.
.It Fl Fl version .It Fl Fl version
Echo the resolvconf version to Echo the resolvconf version to
.Em stdout . .Em stdout .
.El .El
.Pp .Pp
.Nm .Nm
also has some commands designed to be used by it's subscribers and also has some commands designed to be used by its subscribers and
system startup:- system startup:
.Bl -tag -width pattern_opt .Bl -tag -width pattern_opt
.It Fl I .It Fl I
Initialise the state directory Initialise the state directory
.Pa @VARDIR@ . .Pa @VARDIR@ .
This only needs to be called if the initial system boot sequence does not This should be called after the base state directory has either been
automatically clean it out; for example the state directory is moved cleaned out or mounted as a memory backed filesystem during the
somewhere other than initial boot sequence before any daemon has the chance to call
.Pa /var/run . .Nm .
If used, it should only be called once as early in the system boot sequence
as possible and before
.Nm
is used to add interfaces.
.It Fl R .It Fl R
Echo the command used to restart a service. Echo the command used to restart a service.
.It Fl r Ar service .It Fl r Ar service
If the If the
.Ar service .Ar service
is running then restart it. is running then restart it.
If the service does not exist or is not running then zero is returned, If the service does not exist or is not running then zero is returned,
otherwise the result of restarting the service. otherwise the result of restarting the service.
.It Fl v .It Fl v
Echo variables DOMAINS, SEARCH and NAMESERVERS so that the subscriber can Echo variables DOMAINS, SEARCH and NAMESERVERS so that the subscriber can
configure the resolver easily. configure the resolver easily.
.It Fl V .It Fl V
Same as Same as
.Fl v .Fl v
except that only the information configured in except that only the information configured in
.Xr resolvconf.conf 5 .Xr resolvconf.conf 5
is set. is set.
.El .El
.Sh INTERFACE ORDERING .Sh RESOLV.CONF ORDERING
For For
.Nm .Nm
to work effectively, it has to process the resolv.confs for the interfaces to work effectively, it has to process the
in the correct order. .Pa resolv.conf
entries in the correct order.
.Nm .Nm
first processes interfaces from the first processes keys from the
.Sy interface_order .Sy key_order
list, then interfaces without a metic and that match the list, then entries without a metric and that match the
.Sy dynamic_order .Sy dynamic_order
list, then interfaces with a metric in order and finally the rest in list, then entries with a metric in order and finally the rest in
the operating systems lexical order. the operating systems lexical order.
See See
.Xr resolvconf.conf 5 .Xr resolvconf.conf 5
for details on these lists. for details on these lists.
.Sh PROTOCOLS .Sh PROTOCOLS
Here are some suggested protocol tags to use for each Here are some suggested protocol tags to use for each
.Pa resolv.conf .Pa resolv.conf
file registered on an
.Ar interface Ns No :-
.Bl -tag -width pattern_opt .Bl -tag -width pattern_opt
.It dhcp .It dhcp
Dynamic Host Configuration Protocol. Dynamic Host Configuration Protocol.
Initial versions of
.Nm
did not recommend a
.Ar protocol
tag be appended to the
.Ar interface
name.
When the protocol is absent, it is assumed to be the DHCP protocol.
.It ppp .It ppp
Point-to-Point Protocol. Point-to-Point Protocol.
.It ra .It ra
IPv6 Router Advertisement. IPv6 Router Advertisement.
.It dhcp6 .It dhcp6
Dynamic Host Configuration Protocol, version 6. Dynamic Host Configuration Protocol, version 6.
.El .El
.Sh IMPLEMENTATION NOTES .Sh IMPLEMENTATION NOTES
Show All 15 Lines
.Bl -ohang .Bl -ohang
.It Va IF_METRIC .It Va IF_METRIC
If the If the
.Fl m .Fl m
option is not present then we use option is not present then we use
.Va IF_METRIC .Va IF_METRIC
for the metric. for the metric.
.It Va IF_PRIVATE .It Va IF_PRIVATE
Marks the interface Marks the
.Pa resolv.conf .Pa resolv.conf
as private. as private.
.It Va IF_NOSEARCH
Marks the
.Pa resolv.conf
as non-searchable.
.It Va IF_EXCLUSIVE .It Va IF_EXCLUSIVE
Marks the interface Marks the
.Pa resolv.conf .Pa resolv.conf
as exclusive. as exclusive.
.El .El
.Sh FILES .Sh FILES
.Bl -ohang .Bl -ohang
.It Pa /etc/resolv.conf.bak .It Pa /etc/resolv.conf.bak
Backup file of the original resolv.conf. Backup file of the original resolv.conf.
.It Pa @SYSCONFDIR@/resolvconf.conf .It Pa @SYSCONFDIR@/resolvconf.conf
Configuration file for Configuration file for
.Nm . .Nm .
.It Pa @LIBEXECDIR@ .It Pa @LIBEXECDIR@
Directory of subscribers which are run every time Directory of subscribers which are run every time
.Nm .Nm
adds, deletes or updates. adds, deletes or updates.
.It Pa @LIBEXECDIR@/libc.d .It Pa @LIBEXECDIR@/libc.d
Directory of subscribers which are run after the libc subscriber is run. Directory of subscribers which are run after the libc subscriber is run.
.It Pa @VARDIR@ .It Pa @VARDIR@
State directory for State directory for
.Nm . .Nm .
.El .El
.Sh NOTES
Domain labels are assumed to be in ASCII and are converted to lower case
to avoid duplicate zones when given differing case from different sources.
.Pp
When running a local resolver other than libc, you will need to configure it
to include files that
.Nm
will generate.
You should consult
.Xr resolvconf.conf 5
for instructions on how to configure your resolver.
.Sh SEE ALSO .Sh SEE ALSO
.Xr resolver 3 , .Xr resolver 3 ,
.Xr stdin 4 , .Xr stdin 4 ,
.Xr resolv.conf 5 , .Xr resolv.conf 5 ,
.Xr resolvconf.conf 5 .Xr resolvconf.conf 5
.Sh HISTORY .Sh HISTORY
This implementation of This implementation of
.Nm .Nm
is called openresolv and is fully command line compatible with Debian's is called openresolv and is fully command line compatible with Debian's
resolvconf, as written by Thomas Hood. resolvconf, as written by Thomas Hood.
.Sh AUTHORS .Sh AUTHORS
.An Roy Marples Aq Mt roy@marples.name .An Roy Marples Aq Mt roy@marples.name
.Sh BUGS .Sh BUGS
Please report them to Please report them to
.Lk http://roy.marples.name/projects/openresolv .Lk http://roy.marples.name/projects/openresolv
.Pp
.Nm
does not validate any of the files given to it.
.Pp
When running a local resolver other than libc, you will need to configure it
to include files that
.Nm
will generate.
You should consult
.Xr resolvconf.conf 5
for instructions on how to configure your resolver.