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395 lines
17 KiB
XML
395 lines
17 KiB
XML
<?xml version='1.0'?>
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<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
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"http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
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<!--
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This file is part of systemd.
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Copyright 2016 Lennart Poettering
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systemd is free software; you can redistribute it and/or modify it
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under the terms of the GNU Lesser General Public License as published by
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the Free Software Foundation; either version 2.1 of the License, or
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(at your option) any later version.
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systemd is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public License
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along with systemd; If not, see <http://www.gnu.org/licenses/>.
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-->
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<refentry id="systemd-resolve"
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xmlns:xi="http://www.w3.org/2001/XInclude">
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<refentryinfo>
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<title>systemd-resolve</title>
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<productname>systemd</productname>
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<authorgroup>
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<author>
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<contrib>Developer</contrib>
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<firstname>Lennart</firstname>
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<surname>Poettering</surname>
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<email>lennart@poettering.net</email>
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</author>
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</authorgroup>
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</refentryinfo>
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<refmeta>
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<refentrytitle>systemd-resolve</refentrytitle>
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<manvolnum>1</manvolnum>
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</refmeta>
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<refnamediv>
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<refname>systemd-resolve</refname>
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<refpurpose>Resolve domain names, IPV4 and IPv6 addresses, DNS resource records, and services</refpurpose>
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</refnamediv>
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<refsynopsisdiv>
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<cmdsynopsis>
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<command>systemd-resolve</command>
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<arg choice="opt" rep="repeat">OPTIONS</arg>
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<arg choice="plain" rep="repeat"><replaceable>HOSTNAME</replaceable></arg>
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</cmdsynopsis>
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<cmdsynopsis>
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<command>systemd-resolve</command>
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<arg choice="opt" rep="repeat">OPTIONS</arg>
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<arg choice="plain" rep="repeat"><replaceable>ADDRESS</replaceable></arg>
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</cmdsynopsis>
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<cmdsynopsis>
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<command>systemd-resolve</command>
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<arg choice="opt" rep="repeat">OPTIONS</arg>
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<command> --type=<replaceable>TYPE</replaceable></command>
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<arg choice="plain" rep="repeat"><replaceable>DOMAIN</replaceable></arg>
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</cmdsynopsis>
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<cmdsynopsis>
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<command>systemd-resolve</command>
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<arg choice="opt" rep="repeat">OPTIONS</arg>
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<command> --service</command>
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<arg choice="plain"><arg choice="opt"><arg choice="opt"><replaceable>NAME</replaceable></arg>
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<replaceable>TYPE</replaceable></arg> <replaceable>DOMAIN</replaceable></arg>
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</cmdsynopsis>
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<cmdsynopsis>
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<command>systemd-resolve</command>
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<arg choice="opt" rep="repeat">OPTIONS</arg>
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<command> --openpgp</command>
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<arg choice="plain"><replaceable>USER@DOMAIN</replaceable></arg>
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</cmdsynopsis>
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<cmdsynopsis>
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<command>systemd-resolve</command>
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<arg choice="opt" rep="repeat">OPTIONS</arg>
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<command> --tlsa</command>
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<arg choice="plain"><replaceable>DOMAIN<optional>:PORT</optional></replaceable></arg>
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</cmdsynopsis>
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<cmdsynopsis>
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<command>systemd-resolve</command>
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<arg choice="opt" rep="repeat">OPTIONS</arg>
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<command> --statistics</command>
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</cmdsynopsis>
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<cmdsynopsis>
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<command>systemd-resolve</command>
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<arg choice="opt" rep="repeat">OPTIONS</arg>
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<command> --reset-statistics</command>
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</cmdsynopsis>
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</refsynopsisdiv>
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<refsect1>
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<title>Description</title>
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<para><command>systemd-resolve</command> may be used to resolve domain names, IPv4 and IPv6 addresses, DNS resource
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records and services with the
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<citerefentry><refentrytitle>systemd-resolved.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>
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resolver service. By default, the specified list of parameters will be resolved as hostnames, retrieving their IPv4
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and IPv6 addresses. If the parameters specified are formatted as IPv4 or IPv6 operation the reverse operation is
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done, and a hostname is retrieved for the specified addresses.</para>
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<para>The program's output contains information about the protocol used for the look-up and on which network
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interface the data was discovered. It also contains information on whether the information could be
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authenticated. All data for which local DNSSEC validation succeeds is considered authenticated. Moreover all data
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originating from local, trusted sources is also reported authenticated, including resolution of the local host
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name, the <literal>localhost</literal> host name or all data from <filename>/etc/hosts</filename>.</para>
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<para>The <option>--type=</option> switch may be used to specify a DNS resource record type (A, AAAA, SOA, MX, ...) in
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order to request a specific DNS resource record, instead of the address or reverse address lookups.
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The special value <literal>help</literal> may be used to list known values.</para>
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<para>The <option>--service</option> switch may be used to resolve <ulink
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url="https://tools.ietf.org/html/rfc2782">SRV</ulink> and <ulink
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url="https://tools.ietf.org/html/rfc6763">DNS-SD</ulink> services (see below). In this mode, between one and three
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arguments are required. If three parameters are passed the first is assumed to be the DNS-SD service name, the
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second the SRV service type, and the third the domain to search in. In this case a full DNS-SD style SRV and TXT
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lookup is executed. If only two parameters are specified, the first is assumed to be the SRV service type, and the
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second the domain to look in. In this case no TXT RR is requested. Finally, if only one parameter is specified, it
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is assumed to be a domain name, that is already prefixed with an SRV type, and an SRV lookup is done (no
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TXT).</para>
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<para>The <option>--openpgp</option> switch may be used to query PGP keys stored as
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<ulink url="https://tools.ietf.org/html/rfc7929">OPENPGPKEY</ulink> resource records.
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When this option is specified one or more e-mail address must be specified.</para>
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<para>The <option>--tlsa</option> switch maybe be used to query TLS public
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keys stored as
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<ulink url="https://tools.ietf.org/html/rfc6698">TLSA</ulink> resource records.
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When this option is specified one or more domain names must be specified.</para>
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<para>The <option>--statistics</option> switch may be used to show resolver statistics, including information about
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the number of successful and failed DNSSEC validations.</para>
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<para>The <option>--reset-statistics</option> may be used to reset various statistics counters maintained the
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resolver, including those shown in the <option>--statistics</option> output. This operation requires root
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privileges.</para>
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</refsect1>
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<refsect1>
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<title>Options</title>
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<variablelist>
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<varlistentry>
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<term><option>-4</option></term>
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<term><option>-6</option></term>
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<listitem><para>By default, when resolving a hostname, both IPv4 and IPv6
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addresses are acquired. By specifying <option>-4</option> only IPv4 addresses are requested, by specifying
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<option>-6</option> only IPv6 addresses are requested.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><option>-i</option> <replaceable>INTERFACE</replaceable></term>
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<term><option>--interface=</option><replaceable>INTERFACE</replaceable></term>
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<listitem><para>Specifies the network interface to execute the query on. This may either be specified as numeric
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interface index or as network interface string (e.g. <literal>en0</literal>). Note that this option has no
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effect if system-wide DNS configuration (as configured in <filename>/etc/resolv.conf</filename> or
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<filename>/etc/systemd/resolve.conf</filename>) in place of per-link configuration is used.</para></listitem>
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</varlistentry>
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<varlistentry>
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<term><option>-p</option> <replaceable>PROTOCOL</replaceable></term>
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<term><option>--protocol=</option><replaceable>PROTOCOL</replaceable></term>
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<listitem><para>Specifies the network protocol for the query. May be one of <literal>dns</literal>
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(i.e. classic unicast DNS), <literal>llmnr</literal> (<ulink
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url="https://tools.ietf.org/html/rfc4795">Link-Local Multicast Name Resolution</ulink>),
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<literal>llmnr-ipv4</literal>, <literal>llmnr-ipv6</literal> (LLMNR via the indicated underlying IP
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protocols). By default the lookup is done via all protocols suitable for the lookup. If used, limits the set of
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protocols that may be used. Use this option multiple times to enable resolving via multiple protocols at the
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same time. The setting <literal>llmnr</literal> is identical to specifying this switch once with
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<literal>llmnr-ipv4</literal> and once via <literal>llmnr-ipv6</literal>. Note that this option does not force
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the service to resolve the operation with the specified protocol, as that might require a suitable network
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interface and configuration.
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The special value <literal>help</literal> may be used to list known values.
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</para></listitem>
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</varlistentry>
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<varlistentry>
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<term><option>-t</option> <replaceable>TYPE</replaceable></term>
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<term><option>--type=</option><replaceable>TYPE</replaceable></term>
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<term><option>-c</option> <replaceable>CLASS</replaceable></term>
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<term><option>--class=</option><replaceable>CLASS</replaceable></term>
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<listitem><para>Specifies the DNS resource record type (e.g. A, AAAA, MX, …) and class (e.g. IN, ANY, …) to
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look up. If these options are used a DNS resource record set matching the specified class and type is
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requested. The class defaults to IN if only a type is specified.
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The special value <literal>help</literal> may be used to list known values.
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</para></listitem>
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</varlistentry>
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<varlistentry>
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<term><option>--service</option></term>
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<listitem><para>Enables service resolution. This enables DNS-SD and simple SRV service resolution, depending
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on the specified list of parameters (see above).</para></listitem>
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</varlistentry>
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<varlistentry>
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<term><option>--service-address=</option><replaceable>BOOL</replaceable></term>
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<listitem><para>Takes a boolean parameter. If true (the default), when doing a service lookup with
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<option>--service</option> the hostnames contained in the SRV resource records are resolved as well.</para></listitem>
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</varlistentry>
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<varlistentry>
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<term><option>--service-txt=</option><replaceable>BOOL</replaceable></term>
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<listitem><para>Takes a boolean parameter. If true (the default), when doing a DNS-SD service lookup with
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<option>--service</option> the TXT service metadata record is resolved as well.</para></listitem>
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</varlistentry>
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<varlistentry>
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<term><option>--openpgp</option></term>
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<listitem><para>Enables OPENPGPKEY resource record resolution (see above). Specified e-mail
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addresses are converted to the corresponding DNS domain name, and any OPENPGPKEY keys are
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printed.</para></listitem>
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</varlistentry>
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<varlistentry>
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<term><option>--tlsa</option></term>
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<listitem><para>Enables TLSA resource record resolution (see above).
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A query will be performed for each of the specified names prefixed with
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the port and family
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(<literal>_<replaceable>port</replaceable>._<replaceable>family</replaceable>.<replaceable>domain</replaceable></literal>).
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The port number may be specified after a colon
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(<literal>:</literal>), otherwise <constant>443</constant> will be used
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by default. The family may be specified as an argument after
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<option>--tlsa</option>, otherwise <constant>tcp</constant> will be
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used.</para></listitem>
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</varlistentry>
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<varlistentry>
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<term><option>--cname=</option><replaceable>BOOL</replaceable></term>
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<listitem><para>Takes a boolean parameter. If true (the default), DNS CNAME or DNAME redirections are
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followed. Otherwise, if a CNAME or DNAME record is encountered while resolving, an error is
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returned.</para></listitem>
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</varlistentry>
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<varlistentry>
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<term><option>--search=</option><replaceable>BOOL</replaceable></term>
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<listitem><para>Takes a boolean parameter. If true (the default), any specified single-label hostnames will be
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searched in the domains configured in the search domain list, if it is non-empty. Otherwise, the search domain
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logic is disabled.</para></listitem>
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</varlistentry>
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<varlistentry>
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<term><option>--raw</option><optional>=payload|packet</optional></term>
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<listitem><para>Dump the answer as binary data. If there is no argument or if the argument is
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<literal>payload</literal>, the payload of the packet is exported. If the argument is
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<literal>packet</literal>, the whole packet is dumped in wire format, prefixed by
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length specified as a little-endian 64-bit number. This format allows multiple packets
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to be dumped and unambigously parsed.</para></listitem>
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</varlistentry>
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<varlistentry>
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<term><option>--legend=</option><replaceable>BOOL</replaceable></term>
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<listitem><para>Takes a boolean parameter. If true (the default), column headers and meta information about the
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query response are shown. Otherwise, this output is suppressed.</para></listitem>
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</varlistentry>
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<varlistentry>
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<term><option>--statistics</option></term>
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<listitem><para>If specified general resolver statistics are shown, including information whether DNSSEC is
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enabled and available, as well as resolution and validation statistics.</para></listitem>
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</varlistentry>
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<varlistentry>
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<term><option>--reset-statistics</option></term>
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<listitem><para>Resets the statistics counters shown in <option>--statistics</option> to zero.</para></listitem>
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</varlistentry>
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<varlistentry>
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<term><option>--flush-caches</option></term>
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<listitem><para>Flushes all DNS resource record caches the service maintains locally.</para></listitem>
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</varlistentry>
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<varlistentry>
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<term><option>--status</option></term>
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<listitem><para>Shows the global and per-link DNS settings in currently in effect.</para></listitem>
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</varlistentry>
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<xi:include href="standard-options.xml" xpointer="help" />
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<xi:include href="standard-options.xml" xpointer="version" />
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<xi:include href="standard-options.xml" xpointer="no-pager" />
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</variablelist>
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</refsect1>
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<refsect1>
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<title>Examples</title>
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<example>
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<title>Retrieve the addresses of the <literal>www.0pointer.net</literal> domain</title>
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<programlisting>$ systemd-resolve www.0pointer.net
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www.0pointer.net: 2a01:238:43ed:c300:10c3:bcf3:3266:da74
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85.214.157.71
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-- Information acquired via protocol DNS in 611.6ms.
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-- Data is authenticated: no
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</programlisting>
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</example>
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<example>
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<title>Retrieve the domain of the <literal>85.214.157.71</literal> IP address</title>
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<programlisting>$ systemd-resolve 85.214.157.71
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85.214.157.71: gardel.0pointer.net
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-- Information acquired via protocol DNS in 1.2997s.
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-- Data is authenticated: no
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</programlisting>
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</example>
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<example>
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<title>Retrieve the MX record of the <literal>yahoo.com</literal> domain</title>
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<programlisting>$ systemd-resolve -t MX yahoo.com --legend=no
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yahoo.com. IN MX 1 mta7.am0.yahoodns.net
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yahoo.com. IN MX 1 mta6.am0.yahoodns.net
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yahoo.com. IN MX 1 mta5.am0.yahoodns.net
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</programlisting>
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</example>
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<example>
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<title>Resolve an SRV service</title>
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<programlisting>$ systemd-resolve --service _xmpp-server._tcp gmail.com
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_xmpp-server._tcp/gmail.com: alt1.xmpp-server.l.google.com:5269 [priority=20, weight=0]
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173.194.210.125
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alt4.xmpp-server.l.google.com:5269 [priority=20, weight=0]
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173.194.65.125
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...
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</programlisting>
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</example>
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<example>
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<title>Retrieve a PGP key</title>
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<programlisting>$ systemd-resolve --openpgp zbyszek@fedoraproject.org
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d08ee310438ca124a6149ea5cc21b6313b390dce485576eff96f8722._openpgpkey.fedoraproject.org. IN OPENPGPKEY
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mQINBFBHPMsBEACeInGYJCb+7TurKfb6wGyTottCDtiSJB310i37/6ZYoeIay/5soJjlMyf
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MFQ9T2XNT/0LM6gTa0MpC1st9LnzYTMsT6tzRly1D1UbVI6xw0g0vE5y2Cjk3xUwAynCsSs
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...
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</programlisting>
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</example>
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<example>
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<title>Retrieve a TLS key (<literal>=tcp</literal> and
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<literal>:443</literal> could be skipped)</title>
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<programlisting>$ systemd-resolve --tlsa=tcp fedoraproject.org:443
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_443._tcp.fedoraproject.org IN TLSA 0 0 1 19400be5b7a31fb733917700789d2f0a2471c0c9d506c0e504c06c16d7cb17c0
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-- Cert. usage: CA constraint
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-- Selector: Full Certificate
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-- Matching type: SHA-256
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</programlisting>
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</example>
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</refsect1>
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<refsect1>
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<title>See Also</title>
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<para>
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<citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>systemd-resolved.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>
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</para>
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</refsect1>
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</refentry>
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