man/resolvectl.xml

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