3f2a60a137
openresolv: update to version 3.8.1. Among the new features it attempts to support alternative init systems. MFC after: 1 month
319 lines
8.0 KiB
Groff
319 lines
8.0 KiB
Groff
.\" Copyright (c) 2007-2016 Roy Marples
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.\" All rights reserved
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.Dd May 7, 2016
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.Dt RESOLVCONF 8
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.Os
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.Sh NAME
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.Nm resolvconf
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.Nd a framework for managing multiple DNS configurations
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.Sh SYNOPSIS
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.Nm
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.Fl I
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.Nm
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.Op Fl m Ar metric
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.Op Fl p
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.Op Fl x
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.Fl a Ar interface Ns Op Ar .protocol
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.No < Ns Pa file
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.Nm
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.Op Fl f
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.Fl d Ar interface Ns Op Ar .protocol
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.Nm
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.Op Fl x
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.Fl il Ar pattern
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.Nm
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.Fl u
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.Sh DESCRIPTION
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.Nm
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manages
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.Xr resolv.conf 5
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files from multiple sources, such as DHCP and VPN clients.
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Traditionally, the host runs just one client and that updates
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.Pa /etc/resolv.conf .
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More modern systems frequently have wired and wireless interfaces and there is
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no guarantee both are on the same network.
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With the advent of VPN and other
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types of networking daemons, many things now contend for the contents of
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.Pa /etc/resolv.conf .
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.Pp
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.Nm
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solves this by letting the daemon send their
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.Xr resolv.conf 5
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file to
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.Nm
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via
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.Xr stdin 4
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with the argument
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.Fl a Ar interface Ns Op Ar .protocol
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instead of the filesystem.
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.Nm
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then updates
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.Pa /etc/resolv.conf
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as it thinks best.
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When a local resolver other than libc is installed, such as
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.Xr dnsmasq 8
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or
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.Xr named 8 ,
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then
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.Nm
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will supply files that the resolver should be configured to include.
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.Pp
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.Nm
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assumes it has a job to do.
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In some situations
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.Nm
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needs to act as a deterrent to writing to
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.Pa /etc/resolv.conf .
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Where this file cannot be made immutable or you just need to toggle this
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behaviour,
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.Nm
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can be disabled by adding
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.Sy resolvconf Ns = Ns NO
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to
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.Xr resolvconf.conf 5 .
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.Pp
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.Nm
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can mark an interfaces
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.Pa resolv.conf
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as private.
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This means that the name servers listed in that
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.Pa resolv.conf
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are only used for queries against the domain/search listed in the same file.
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This only works when a local resolver other than libc is installed.
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See
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.Xr resolvconf.conf 5
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for how to configure
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.Nm
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to use a local name server.
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.Pp
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.Nm
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can mark an interfaces
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.Pa resolv.conf
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as exclusive.
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Only the latest exclusive interface is used for processing, otherwise all are.
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.Pp
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When an interface goes down, it should then call
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.Nm
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with
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.Fl d Ar interface.*
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arguments to delete the
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.Pa resolv.conf
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file(s) for all the
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.Ar protocols
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on the
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.Ar interface .
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.Pp
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Here are some options for the above commands:-
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.Bl -tag -width indent
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.It Fl f
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Ignore non existent interfaces.
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Only really useful for deleting interfaces.
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.It Fl m Ar metric
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Set the metric of the interface when adding it, default of 0.
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Lower metrics take precedence.
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This affects the default order of interfaces when listed.
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.It Fl p
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Marks the interface
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.Pa resolv.conf
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as private.
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.It Fl x
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Mark the interface
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.Pa resolv.conf
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as exclusive when adding, otherwise only use the latest exclusive interface.
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.El
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.Pp
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.Nm
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has some more commands for general usage:-
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.Bl -tag -width indent
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.It Fl i Ar pattern
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List the interfaces and protocols, optionally matching
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.Ar pattern ,
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we have
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.Pa resolv.conf
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files for.
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.It Fl l Ar pattern
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List the
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.Pa resolv.conf
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files we have.
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If
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.Ar pattern
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is specified then we list the files for the interfaces and protocols
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that match it.
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.It Fl u
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Force
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.Nm
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to update all its subscribers.
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.Nm
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does not update the subscribers when adding a resolv.conf that matches
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what it already has for that interface.
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.El
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.Pp
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.Nm
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also has some commands designed to be used by it's subscribers and
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system startup:-
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.Bl -tag -width indent
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.It Fl I
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Initialise the state directory
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.Pa @VARDIR@ .
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This only needs to be called if the initial system boot sequence does not
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automatically clean it out; for example the state directory is moved
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somewhere other than
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.Pa /var/run .
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If used, it should only be called once as early in the system boot sequence
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as possible and before
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.Nm
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is used to add interfaces.
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.It Fl R
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Echo the command used to restart a service.
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.It Fl r Ar service
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If the
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.Ar service
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is running then restart it.
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If the service does not exist or is not running then zero is returned,
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otherwise the result of restarting the service.
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.It Fl v
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Echo variables DOMAINS, SEARCH and NAMESERVERS so that the subscriber can
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configure the resolver easily.
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.It Fl V
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Same as
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.Fl v
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except that only the information configured in
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.Xr resolvconf.conf 5
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is set.
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.El
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.Sh INTERFACE ORDERING
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For
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.Nm
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to work effectively, it has to process the resolv.confs for the interfaces
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in the correct order.
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.Nm
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first processes interfaces from the
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.Sy interface_order
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list, then interfaces without a metic and that match the
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.Sy dynamic_order
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list, then interfaces with a metric in order and finally the rest in
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the operating systems lexical order.
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See
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.Xr resolvconf.conf 5
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for details on these lists.
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.Sh PROTOCOLS
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Here are some suggested protocol tags to use for each
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.Pa resolv.conf
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file registered on an
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.Ar interface Ns No :-
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.Bl -tag -width indent
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.It dhcp
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Dynamic Host Configuration Protocol.
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Initial versions of
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.Nm
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did not recommend a
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.Ar protocol
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tag be appended to the
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.Ar interface
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name.
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When the protocol is absent, it is assumed to be the DHCP protocol.
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.It ppp
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Point-to-Point Protocol.
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.It ra
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IPv6 Router Advertisement.
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.It dhcp6
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Dynamic Host Configuration Protocol, version 6.
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.El
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.Sh IMPLEMENTATION NOTES
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If a subscriber has the executable bit then it is executed otherwise it is
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assumed to be a shell script and sourced into the current environment in a
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subshell.
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This is done so that subscribers can remain fast, but are also not limited
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to the shell language.
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.Pp
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Portable subscribers should not use anything outside of
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.Pa /bin
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and
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.Pa /sbin
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because
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.Pa /usr
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and others may not be available when booting.
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Also, it would be unwise to assume any shell specific features.
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.Sh ENVIRONMENT
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.Bl -ohang
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.It Va IF_METRIC
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If the
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.Fl m
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option is not present then we use
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.Va IF_METRIC
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for the metric.
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.It Va IF_PRIVATE
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Marks the interface
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.Pa resolv.conf
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as private.
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.It Va IF_EXCLUSIVE
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Marks the interface
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.Pa resolv.conf
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as exclusive.
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.El
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.Sh FILES
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.Bl -ohang
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.It Pa /etc/resolv.conf.bak
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Backup file of the original resolv.conf.
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.It Pa @SYSCONFDIR@/resolvconf.conf
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Configuration file for
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.Nm .
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.It Pa @LIBEXECDIR@
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Directory of subscribers which are run every time
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.Nm
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adds, deletes or updates.
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.It Pa @LIBEXECDIR@/libc.d
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Directory of subscribers which are run after the libc subscriber is run.
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.It Pa @VARDIR@
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State directory for
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.Nm .
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.El
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.Sh SEE ALSO
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.Xr resolver 3 ,
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.Xr stdin 4 ,
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.Xr resolv.conf 5 ,
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.Xr resolvconf.conf 5
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.Sh HISTORY
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This implementation of
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.Nm
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is called openresolv and is fully command line compatible with Debian's
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resolvconf, as written by Thomas Hood.
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.Sh AUTHORS
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.An Roy Marples Aq Mt roy@marples.name
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.Sh BUGS
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Please report them to
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.Lk http://roy.marples.name/projects/openresolv
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.Pp
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.Nm
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does not validate any of the files given to it.
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.Pp
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When running a local resolver other than libc, you will need to configure it
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to include files that
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.Nm
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will generate.
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You should consult
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.Xr resolvconf.conf 5
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for instructions on how to configure your resolver.
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