man/resolvectl.xml

   1 <?xml version='1.0'?>
   2 <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
   3 "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
   4
   5 <!--
   6   SPDX-License-Identifier: LGPL-2.1+
   7
   8   Copyright 2016 Lennart Poettering
   9 -->
  10
  11 <refentry id="resolvectl" conditional='ENABLE_RESOLVE'
  12           xmlns:xi="http://www.w3.org/2001/XInclude">
  13
  14   <refentryinfo>
  15     <title>resolvectl</title>
  16     <productname>systemd</productname>
  17
  18     <authorgroup>
  19       <author>
  20         <contrib>Developer</contrib>
  21         <firstname>Lennart</firstname>
  22         <surname>Poettering</surname>
  23         <email>lennart@poettering.net</email>
  24       </author>
  25     </authorgroup>
  26   </refentryinfo>
  27
  28   <refmeta>
  29     <refentrytitle>resolvectl</refentrytitle>
  30     <manvolnum>1</manvolnum>
  31   </refmeta>
  32
  33   <refnamediv>
  34     <refname>resolvectl</refname>
  35     <refname>resolvconf</refname>
  36     <refpurpose>Resolve domain names, IPV4 and IPv6 addresses, DNS resource records, and services; introspect and reconfigure the DNS resolver</refpurpose>
  37   </refnamediv>
  38
  39   <refsynopsisdiv>
  40     <cmdsynopsis>
  41       <command>resolvectl</command>
  42       <arg choice="opt" rep="repeat">OPTIONS</arg>
  43       <arg choice="req">COMMAND</arg>
  44       <arg choice="opt" rep="repeat">NAME</arg>
  45     </cmdsynopsis>
  46   </refsynopsisdiv>
  47
  48   <refsect1>
  49     <title>Description</title>
  50
  51     <para><command>resolvectl</command> may be used to resolve domain names, IPv4 and IPv6 addresses, DNS resource
  52     records and services with the
  53     <citerefentry><refentrytitle>systemd-resolved.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>
  54     resolver service. By default, the specified list of parameters will be resolved as hostnames, retrieving their IPv4
  55     and IPv6 addresses. If the parameters specified are formatted as IPv4 or IPv6 operation the reverse operation is
  56     done, and a hostname is retrieved for the specified addresses.</para>
  57
  58     <para>The program's output contains information about the protocol used for the look-up and on which network
  59     interface the data was discovered. It also contains information on whether the information could be
  60     authenticated. All data for which local DNSSEC validation succeeds is considered authenticated. Moreover all data
  61     originating from local, trusted sources is also reported authenticated, including resolution of the local host
  62     name, the <literal>localhost</literal> host name or all data from <filename>/etc/hosts</filename>.</para>
  63   </refsect1>
  64
  65   <refsect1>
  66     <title>Options</title>
  67     <variablelist>
  68       <varlistentry>
  69         <term><option>-4</option></term>
  70         <term><option>-6</option></term>
  71
  72         <listitem><para>By default, when resolving a hostname, both IPv4 and IPv6
  73         addresses are acquired. By specifying <option>-4</option> only IPv4 addresses are requested, by specifying
  74         <option>-6</option> only IPv6 addresses are requested.</para>
  75         </listitem>
  76       </varlistentry>
  77
  78       <varlistentry>
  79         <term><option>-i</option> <replaceable>INTERFACE</replaceable></term>
  80         <term><option>--interface=</option><replaceable>INTERFACE</replaceable></term>
  81
  82         <listitem><para>Specifies the network interface to execute the query on. This may either be specified as numeric
  83         interface index or as network interface string (e.g. <literal>en0</literal>). Note that this option has no
  84         effect if system-wide DNS configuration (as configured in <filename>/etc/resolv.conf</filename> or
  85         <filename>/etc/systemd/resolve.conf</filename>) in place of per-link configuration is used.</para></listitem>
  86       </varlistentry>
  87
  88       <varlistentry>
  89         <term><option>-p</option> <replaceable>PROTOCOL</replaceable></term>
  90         <term><option>--protocol=</option><replaceable>PROTOCOL</replaceable></term>
  91
  92         <listitem><para>Specifies the network protocol for the query. May be one of <literal>dns</literal>
  93         (i.e. classic unicast DNS), <literal>llmnr</literal> (<ulink
  94         url="https://tools.ietf.org/html/rfc4795">Link-Local Multicast Name Resolution</ulink>),
  95         <literal>llmnr-ipv4</literal>, <literal>llmnr-ipv6</literal> (LLMNR via the indicated underlying IP
  96         protocols), <literal>mdns</literal> (<ulink url="https://www.ietf.org/rfc/rfc6762.txt">Multicast DNS</ulink>),
  97         <literal>mdns-ipv4</literal>, <literal>mdns-ipv6</literal> (MDNS via the indicated underlying IP protocols).
  98         By default the lookup is done via all protocols suitable for the lookup. If used, limits the set of
  99         protocols that may be used. Use this option multiple times to enable resolving via multiple protocols at the
 100         same time. The setting <literal>llmnr</literal> is identical to specifying this switch once with
 101         <literal>llmnr-ipv4</literal> and once via <literal>llmnr-ipv6</literal>. Note that this option does not force
 102         the service to resolve the operation with the specified protocol, as that might require a suitable network
 103         interface and configuration.
 104         The special value <literal>help</literal> may be used to list known values.
 105         </para></listitem>
 106       </varlistentry>
 107
 108       <varlistentry>
 109         <term><option>-t</option> <replaceable>TYPE</replaceable></term>
 110         <term><option>--type=</option><replaceable>TYPE</replaceable></term>
 111         <term><option>-c</option> <replaceable>CLASS</replaceable></term>
 112         <term><option>--class=</option><replaceable>CLASS</replaceable></term>
 113
 114         <listitem><para>Specifies the DNS resource record type (e.g. A, AAAA, MX, …) and class (e.g. IN, ANY, …) to
 115         look up. If these options are used a DNS resource record set matching the specified class and type is
 116         requested. The class defaults to IN if only a type is specified.
 117         The special value <literal>help</literal> may be used to list known values.
 118         </para></listitem>
 119       </varlistentry>
 120
 121       <varlistentry>
 122         <term><option>--service-address=</option><replaceable>BOOL</replaceable></term>
 123
 124         <listitem><para>Takes a boolean parameter. If true (the default), when doing a service lookup with
 125         <option>--service</option> the hostnames contained in the SRV resource records are resolved as well.</para></listitem>
 126       </varlistentry>
 127
 128       <varlistentry>
 129         <term><option>--service-txt=</option><replaceable>BOOL</replaceable></term>
 130
 131         <listitem><para>Takes a boolean parameter. If true (the default), when doing a DNS-SD service lookup with
 132         <option>--service</option> the TXT service metadata record is resolved as well.</para></listitem>
 133       </varlistentry>
 134
 135       <varlistentry>
 136         <term><option>--cname=</option><replaceable>BOOL</replaceable></term>
 137
 138         <listitem><para>Takes a boolean parameter. If true (the default), DNS CNAME or DNAME redirections are
 139         followed. Otherwise, if a CNAME or DNAME record is encountered while resolving, an error is
 140         returned.</para></listitem>
 141       </varlistentry>
 142
 143       <varlistentry>
 144         <term><option>--search=</option><replaceable>BOOL</replaceable></term>
 145
 146         <listitem><para>Takes a boolean parameter. If true (the default), any specified single-label hostnames will be
 147         searched in the domains configured in the search domain list, if it is non-empty. Otherwise, the search domain
 148         logic is disabled.</para></listitem>
 149       </varlistentry>
 150
 151       <varlistentry>
 152         <term><option>--raw</option><optional>=payload|packet</optional></term>
 153
 154         <listitem><para>Dump the answer as binary data. If there is no argument or if the argument is
 155         <literal>payload</literal>, the payload of the packet is exported. If the argument is
 156         <literal>packet</literal>, the whole packet is dumped in wire format, prefixed by
 157         length specified as a little-endian 64-bit number. This format allows multiple packets
 158         to be dumped and unambiguously parsed.</para></listitem>
 159       </varlistentry>
 160
 161       <varlistentry>
 162         <term><option>--legend=</option><replaceable>BOOL</replaceable></term>
 163
 164         <listitem><para>Takes a boolean parameter. If true (the default), column headers and meta information about the
 165         query response are shown. Otherwise, this output is suppressed.</para></listitem>
 166       </varlistentry>
 167
 168       <xi:include href="standard-options.xml" xpointer="help" />
 169       <xi:include href="standard-options.xml" xpointer="version" />
 170       <xi:include href="standard-options.xml" xpointer="no-pager" />
 171     </variablelist>
 172   </refsect1>
 173
 174   <refsect1>
 175     <title>Commands</title>
 176     <variablelist>
 177
 178       <varlistentry>
 179         <term><option>query <replaceable>HOSTNAME|ADDRESS</replaceable>…</option></term>
 180
 181         <listitem><para>Resolve domain names, IPv4 and IPv6 addresses.</para></listitem>
 182       </varlistentry>
 183
 184       <varlistentry>
 185         <term><option>service [[<replaceable>NAME</replaceable>] <replaceable>TYPE</replaceable>] <replaceable>DOMAIN</replaceable></option></term>
 186
 187         <listitem><para>Resolve <ulink url="https://tools.ietf.org/html/rfc6763">DNS-SD</ulink> and
 188         <ulink url="https://tools.ietf.org/html/rfc2782">SRV</ulink> services, depending on the specified list of parameters.
 189         If three parameters are passed the first is assumed to be the DNS-SD service name, the second the SRV service type,
 190         and the third the domain to search in. In this case a full DNS-SD style SRV and TXT lookup is executed. If only two
 191         parameters are specified, the first is assumed to be the SRV service type, and the second the domain to look in. In
 192         this case no TXT RR is requested. Finally, if only one parameter is specified, it is assumed to be a domain name,
 193         that is already prefixed with an SRV type, and an SRV lookup is done (no TXT).</para></listitem>
 194       </varlistentry>
 195
 196       <varlistentry>
 197         <term><option>openpgp <replaceable>EMAIL@DOMAIN</replaceable>…</option></term>
 198
 199         <listitem><para>Query PGP keys stored as <ulink url="https://tools.ietf.org/html/rfc7929">OPENPGPKEY</ulink>
 200         resource records. Specified e-mail addresses are converted to the corresponding DNS domain name, and any
 201         OPENPGPKEY keys are printed.</para></listitem>
 202       </varlistentry>
 203
 204       <varlistentry>
 205         <term><option>tlsa [<replaceable>FAMILY</replaceable>] <replaceable>DOMAIN</replaceable>[:<replaceable>PORT</replaceable>]…</option></term>
 206
 207         <listitem><para>Query TLS public keys stored as <ulink url="https://tools.ietf.org/html/rfc6698">TLSA</ulink>
 208         resource records. A query will be performed for each of the specified names prefixed with the port and family
 209         (<literal>_<replaceable>port</replaceable>._<replaceable>family</replaceable>.<replaceable>domain</replaceable></literal>).
 210         The port number may be specified after a colon (<literal>:</literal>), otherwise <constant>443</constant> will be used
 211         by default. The family may be specified as the first argument, otherwise <constant>tcp</constant> will be used.</para></listitem>
 212       </varlistentry>
 213
 214       <varlistentry>
 215         <term><option>status [<replaceable>LINK</replaceable>…]</option></term>
 216
 217         <listitem><para>Shows the global and per-link DNS settings in currently in effect. If no command is specified,
 218         this is the implied default.</para></listitem>
 219       </varlistentry>
 220
 221       <varlistentry>
 222         <term><option>statistics</option></term>
 223
 224         <listitem><para>Shows general resolver statistics, including information whether DNSSEC is
 225         enabled and available, as well as resolution and validation statistics.</para></listitem>
 226       </varlistentry>
 227
 228       <varlistentry>
 229         <term><option>reset-statistics</option></term>
 230
 231         <listitem><para>Resets the statistics counters shown in <option>statistics</option> to zero.
 232         This operation requires root privileges.</para></listitem>
 233       </varlistentry>
 234
 235       <varlistentry>
 236         <term><option>flush-caches</option></term>
 237
 238         <listitem><para>Flushes all DNS resource record caches the service maintains locally. This is mostly equivalent
 239         to sending the <constant>SIGUSR2</constant> to the <command>systemd-resolved</command>
 240         service.</para></listitem>
 241       </varlistentry>
 242
 243       <varlistentry>
 244         <term><option>reset-server-features</option></term>
 245
 246         <listitem><para>Flushes all feature level information the resolver learnt about specific servers, and ensures
 247         that the server feature probing logic is started from the beginning with the next look-up request. This is
 248         mostly equivalent to sending the <constant>SIGRTMIN+1</constant> to the <command>systemd-resolved</command>
 249         service.</para></listitem>
 250       </varlistentry>
 251
 252       <varlistentry>
 253         <term><option>dns [<replaceable>LINK</replaceable> [<replaceable>SERVER</replaceable>…]]</option></term>
 254         <term><option>domain [<replaceable>LINK</replaceable> [<replaceable>DOMAIN</replaceable>…]]</option></term>
 255         <term><option>llmnr [<replaceable>LINK</replaceable> [<replaceable>MODE</replaceable>]]</option></term>
 256         <term><option>mdns [<replaceable>LINK</replaceable> [<replaceable>MODE</replaceable>]]</option></term>
 257         <term><option>dnssec [<replaceable>LINK</replaceable> [<replaceable>MODE</replaceable>]]</option></term>
 258         <term><option>dnsovertls [<replaceable>LINK</replaceable> [<replaceable>MODE</replaceable>]]</option></term>
 259         <term><option>nta [<replaceable>LINK</replaceable> [<replaceable>DOMAIN</replaceable>…]]</option></term>
 260
 261         <listitem><para>Get/set per-interface DNS configuration. These commands may be used to configure various DNS
 262         settings for network interfaces that aren't managed by
 263         <citerefentry><refentrytitle>systemd-networkd.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>. (These
 264         commands will fail when used on interfaces that are managed by <command>systemd-networkd</command>, please
 265         configure their DNS settings directly inside the <filename>.network</filename> files instead.) These commands
 266         may be used to inform <command>systemd-resolved</command> about per-interface DNS configuration determined
 267         through external means. The <option>dns</option> command expects IPv4 or IPv6 address specifications of DNS
 268         servers to use. The <option>domain</option> command expects valid DNS domains, possibly prefixed with
 269         <literal>~</literal>, and configures a per-interface search or route-only domain. The <option>llmnr</option>,
 270         <option>mdns</option>, <option>dnssec</option> and <option>dnsovertls</option> commands may be used to configure
 271         the per-interface LLMNR, MulticastDNS, DNSSEC and DNSOverTLS settings. Finally, <option>nta</option> command
 272         may be used to configure additional per-interface DNSSEC NTA domains. For details about these settings, their
 273         possible values and their effect, see the corresponding options in
 274         <citerefentry><refentrytitle>systemd.network</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para>
 275         </listitem>
 276       </varlistentry>
 277
 278       <varlistentry>
 279         <term><option>revert <replaceable>LINK</replaceable></option></term>
 280
 281         <listitem><para>Revert the per-interface DNS configuration. If the DNS configuration is reverted all
 282         per-interface DNS setting are reset to their defaults, undoing all effects of <option>dns</option>,
 283         <option>domain</option>, <option>llmnr</option>, <option>mdns</option>, <option>dnssec</option>,
 284         <option>dnsovertls</option>, <option>nta</option>. Note that when a network interface disappears all
 285         configuration is lost automatically, an explicit reverting is not necessary in that case.</para></listitem>
 286       </varlistentry>
 287
 288     </variablelist>
 289   </refsect1>
 290
 291   <refsect1>
 292     <title>Compatibility with <citerefentry><refentrytitle>resolvconf</refentrytitle><manvolnum>8</manvolnum></citerefentry></title>
 293
 294     <para><command>resolvectl</command> is a multi-call binary. When invoked as <literal>resolvconf</literal>
 295     (generally achieved by means of a symbolic link of this name to the <command>resolvectl</command> binary) it
 296     is run in a limited <citerefentry><refentrytitle>resolvconf</refentrytitle><manvolnum>8</manvolnum></citerefentry>
 297     compatibility mode. It accepts mostly the same arguments and pushes all data into
 298     <citerefentry><refentrytitle>systemd-resolved.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
 299     similar to how <option>dns</option> and <option>domain</option> commands operate. Note that
 300     <command>systemd-resolved.service</command> is the only supported backend, which is different from other
 301     implementations of this command. Note that not all operations supported by other implementations are supported
 302     natively. Specifically:</para>
 303
 304     <variablelist>
 305       <varlistentry>
 306         <term><option>-a</option></term>
 307         <listitem><para>Registers per-interface DNS configuration data with
 308         <command>systemd-resolved</command>. Expects a network interface name as only command line argument. Reads
 309         <citerefentry><refentrytitle>resolv.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry> compatible DNS
 310         configuration data from its standard input. Relevant fields are <literal>nameserver</literal> and
 311         <literal>domain</literal>/<literal>search</literal>. This command is mostly identical to invoking
 312         <command>resolvectl</command> with a combination of <option>dns</option> and
 313         <option>domain</option> commands.</para></listitem>
 314       </varlistentry>
 315
 316       <varlistentry>
 317         <term><option>-d</option></term>
 318         <listitem><para>Unregisters per-interface DNS configuration data with <command>systemd-resolved</command>. This
 319         command is mostly identical to invoking <command>resolvectl revert</command>.</para></listitem>
 320       </varlistentry>
 321
 322       <varlistentry>
 323         <term><option>-f</option></term>
 324
 325         <listitem><para>When specified <option>-a</option> and <option>-d</option> will not complain about missing
 326         network interfaces and will silently execute no operation in that case.</para></listitem>
 327       </varlistentry>
 328
 329       <varlistentry>
 330         <term><option>-x</option></term>
 331
 332         <listitem><para>This switch for "exclusive" operation is supported only partially. It is mapped to an
 333         additional configured search domain of <literal>~.</literal> — i.e. ensures that DNS traffic is preferably
 334         routed to the DNS servers on this interface, unless there are other, more specific domains configured on other
 335         interfaces.</para></listitem>
 336       </varlistentry>
 337
 338       <varlistentry>
 339         <term><option>-m</option></term>
 340         <term><option>-p</option></term>
 341
 342         <listitem><para>These switches are not supported and are silently ignored.</para></listitem>
 343       </varlistentry>
 344
 345       <varlistentry>
 346         <term><option>-u</option></term>
 347         <term><option>-I</option></term>
 348         <term><option>-i</option></term>
 349         <term><option>-l</option></term>
 350         <term><option>-R</option></term>
 351         <term><option>-r</option></term>
 352         <term><option>-v</option></term>
 353         <term><option>-V</option></term>
 354         <term><option>--enable-updates</option></term>
 355         <term><option>--disable-updates</option></term>
 356         <term><option>--are-updates-enabled</option></term>
 357
 358         <listitem><para>These switches are not supported and the command will fail if used.</para></listitem>
 359       </varlistentry>
 360
 361     </variablelist>
 362
 363     <para>See <citerefentry><refentrytitle>resolvconf</refentrytitle><manvolnum>8</manvolnum></citerefentry> for details on this command line options.</para>
 364   </refsect1>
 365
 366   <refsect1>
 367     <title>Examples</title>
 368
 369     <example>
 370       <title>Retrieve the addresses of the <literal>www.0pointer.net</literal> domain</title>
 371
 372       <programlisting>$ resolvectl query www.0pointer.net
 373 www.0pointer.net: 2a01:238:43ed:c300:10c3:bcf3:3266:da74
 374                   85.214.157.71
 375
 376 -- Information acquired via protocol DNS in 611.6ms.
 377 -- Data is authenticated: no
 378 </programlisting>
 379     </example>
 380
 381     <example>
 382       <title>Retrieve the domain of the <literal>85.214.157.71</literal> IP address</title>
 383
 384       <programlisting>$ resolvectl query 85.214.157.71
 385 85.214.157.71: gardel.0pointer.net
 386
 387 -- Information acquired via protocol DNS in 1.2997s.
 388 -- Data is authenticated: no
 389 </programlisting>
 390     </example>
 391
 392     <example>
 393       <title>Retrieve the MX record of the <literal>yahoo.com</literal> domain</title>
 394
 395       <programlisting>$ resolvectl --legend=no -t MX query yahoo.com
 396 yahoo.com. IN MX    1 mta7.am0.yahoodns.net
 397 yahoo.com. IN MX    1 mta6.am0.yahoodns.net
 398 yahoo.com. IN MX    1 mta5.am0.yahoodns.net
 399 </programlisting>
 400     </example>
 401
 402     <example>
 403       <title>Resolve an SRV service</title>
 404
 405       <programlisting>$ resolvectl service _xmpp-server._tcp gmail.com
 406 _xmpp-server._tcp/gmail.com: alt1.xmpp-server.l.google.com:5269 [priority=20, weight=0]
 407                              173.194.210.125
 408                              alt4.xmpp-server.l.google.com:5269 [priority=20, weight=0]
 409                              173.194.65.125
 410                              …
 411 </programlisting>
 412     </example>
 413
 414     <example>
 415       <title>Retrieve a PGP key</title>
 416
 417       <programlisting>$ resolvectl openpgp zbyszek@fedoraproject.org
 418 d08ee310438ca124a6149ea5cc21b6313b390dce485576eff96f8722._openpgpkey.fedoraproject.org. IN OPENPGPKEY
 419         mQINBFBHPMsBEACeInGYJCb+7TurKfb6wGyTottCDtiSJB310i37/6ZYoeIay/5soJjlMyf
 420         MFQ9T2XNT/0LM6gTa0MpC1st9LnzYTMsT6tzRly1D1UbVI6xw0g0vE5y2Cjk3xUwAynCsSs
 421         …
 422 </programlisting>
 423     </example>
 424
 425     <example>
 426       <title>Retrieve a TLS key (<literal>tcp</literal> and
 427       <literal>:443</literal> could be skipped)</title>
 428
 429       <programlisting>$ resolvectl tlsa tcp fedoraproject.org:443
 430 _443._tcp.fedoraproject.org IN TLSA 0 0 1 19400be5b7a31fb733917700789d2f0a2471c0c9d506c0e504c06c16d7cb17c0
 431         -- Cert. usage: CA constraint
 432         -- Selector: Full Certificate
 433         -- Matching type: SHA-256
 434 </programlisting>
 435     </example>
 436   </refsect1>
 437
 438   <refsect1>
 439     <title>See Also</title>
 440     <para>
 441       <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
 442       <citerefentry><refentrytitle>systemd-resolved.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
 443       <citerefentry><refentrytitle>systemd.dnssd</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 444       <citerefentry><refentrytitle>systemd-networkd.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
 445       <citerefentry><refentrytitle>resolvconf</refentrytitle><manvolnum>8</manvolnum></citerefentry>
 446     </para>
 447   </refsect1>
 448 </refentry>