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> hostname or all data from <filename>/etc/hosts</filename>.</para>
  49   </refsect1>
  50
  51   <refsect1>
  52     <title>Commands</title>
  53     <variablelist>
  54
  55       <varlistentry>
  56         <term><command>query</command> <replaceable>HOSTNAME|ADDRESS</replaceable>…</term>
  57
  58         <listitem><para>Resolve domain names, IPv4 and IPv6 addresses.</para></listitem>
  59       </varlistentry>
  60
  61       <varlistentry>
  62         <term><command>service</command>
  63         [[<replaceable>NAME</replaceable>] <replaceable>TYPE</replaceable>]
  64         <replaceable>DOMAIN</replaceable></term>
  65
  66         <listitem><para>Resolve <ulink url="https://tools.ietf.org/html/rfc6763">DNS-SD</ulink> and
  67         <ulink url="https://tools.ietf.org/html/rfc2782">SRV</ulink> services, depending on the specified list of parameters.
  68         If three parameters are passed the first is assumed to be the DNS-SD service name, the second the SRV service type,
  69         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
  70         parameters are specified, the first is assumed to be the SRV service type, and the second the domain to look in. In
  71         this case no TXT RR is requested. Finally, if only one parameter is specified, it is assumed to be a domain name,
  72         that is already prefixed with an SRV type, and an SRV lookup is done (no TXT).</para></listitem>
  73       </varlistentry>
  74
  75       <varlistentry>
  76         <term><command>openpgp</command> <replaceable>EMAIL@DOMAIN</replaceable>…</term>
  77
  78         <listitem><para>Query PGP keys stored as <ulink url="https://tools.ietf.org/html/rfc7929">OPENPGPKEY</ulink>
  79         resource records. Specified e-mail addresses are converted to the corresponding DNS domain name, and any
  80         OPENPGPKEY keys are printed.</para></listitem>
  81       </varlistentry>
  82
  83       <varlistentry>
  84         <term><command>tlsa</command>
  85         [<replaceable>FAMILY</replaceable>]
  86         <replaceable>DOMAIN</replaceable>[:<replaceable>PORT</replaceable>]…</term>
  87
  88         <listitem><para>Query TLS public keys stored as <ulink url="https://tools.ietf.org/html/rfc6698">TLSA</ulink>
  89         resource records. A query will be performed for each of the specified names prefixed with the port and family
  90         (<literal>_<replaceable>port</replaceable>._<replaceable>family</replaceable>.<replaceable>domain</replaceable></literal>).
  91         The port number may be specified after a colon (<literal>:</literal>), otherwise <constant>443</constant> will be used
  92         by default. The family may be specified as the first argument, otherwise <constant>tcp</constant> will be used.</para></listitem>
  93       </varlistentry>
  94
  95       <varlistentry>
  96         <term><command>status</command> [<replaceable>LINK</replaceable>…]</term>
  97
  98         <listitem><para>Shows the global and per-link DNS settings currently in effect. If no command is specified,
  99         this is the implied default.</para></listitem>
 100       </varlistentry>
 101
 102       <varlistentry>
 103         <term><command>statistics</command></term>
 104
 105         <listitem><para>Shows general resolver statistics, including information whether DNSSEC is
 106         enabled and available, as well as resolution and validation statistics.</para></listitem>
 107       </varlistentry>
 108
 109       <varlistentry>
 110         <term><command>reset-statistics</command></term>
 111
 112         <listitem><para>Resets the statistics counters shown in <command>statistics</command> to zero.
 113         This operation requires root privileges.</para></listitem>
 114       </varlistentry>
 115
 116       <varlistentry>
 117         <term><command>flush-caches</command></term>
 118
 119         <listitem><para>Flushes all DNS resource record caches the service maintains locally. This is mostly equivalent
 120         to sending the <constant>SIGUSR2</constant> to the <command>systemd-resolved</command>
 121         service.</para></listitem>
 122       </varlistentry>
 123
 124       <varlistentry>
 125         <term><command>reset-server-features</command></term>
 126
 127         <listitem><para>Flushes all feature level information the resolver learnt about specific servers, and ensures
 128         that the server feature probing logic is started from the beginning with the next look-up request. This is
 129         mostly equivalent to sending the <constant>SIGRTMIN+1</constant> to the <command>systemd-resolved</command>
 130         service.</para></listitem>
 131       </varlistentry>
 132
 133       <varlistentry>
 134         <term><command>dns</command> [<replaceable>LINK</replaceable> [<replaceable>SERVER</replaceable>…]]</term>
 135         <term><command>domain</command> [<replaceable>LINK</replaceable> [<replaceable>DOMAIN</replaceable>…]]</term>
 136         <term><command>default-route</command> [<replaceable>LINK</replaceable> [<replaceable>BOOL</replaceable>…]]</term>
 137         <term><command>llmnr</command> [<replaceable>LINK</replaceable> [<replaceable>MODE</replaceable>]]</term>
 138         <term><command>mdns</command> [<replaceable>LINK</replaceable> [<replaceable>MODE</replaceable>]]</term>
 139         <term><command>dnssec</command> [<replaceable>LINK</replaceable> [<replaceable>MODE</replaceable>]]</term>
 140         <term><command>dnsovertls</command> [<replaceable>LINK</replaceable> [<replaceable>MODE</replaceable>]]</term>
 141         <term><command>nta</command> [<replaceable>LINK</replaceable> [<replaceable>DOMAIN</replaceable>…]]</term>
 142
 143         <listitem>
 144           <para>Get/set per-interface DNS configuration. These commands may be used to configure various DNS
 145           settings for network interfaces. These commands may be used to inform
 146           <command>systemd-resolved</command> or <command>systemd-networkd</command> about per-interface DNS
 147           configuration determined through external means. The <command>dns</command> command expects IPv4 or
 148           IPv6 address specifications of DNS servers to use. The <command>domain</command> command expects
 149           valid DNS domains, possibly prefixed with <literal>~</literal>, and configures a per-interface
 150           search or route-only domain. The <command>default-route</command> command expects a boolean
 151           parameter, and configures whether the link may be used as default route for DNS lookups, i.e. if it
 152           is suitable for lookups on domains no other link explicitly is configured for. The
 153           <command>llmnr</command>, <command>mdns</command>, <command>dnssec</command> and
 154           <command>dnsovertls</command> commands may be used to configure the per-interface LLMNR,
 155           MulticastDNS, DNSSEC and DNSOverTLS settings. Finally, <command>nta</command> command may be used
 156           to configure additional per-interface DNSSEC NTA domains.</para>
 157
 158           <para>Commands <command>dns</command>, <command>domain</command> and <command>nta</command> can take
 159           a single empty string argument to clear their respective value lists.</para>
 160
 161           <para>For details about these settings, their possible values and their effect, see the
 162           corresponding settings in
 163           <citerefentry><refentrytitle>systemd.network</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para>
 164         </listitem>
 165       </varlistentry>
 166
 167       <varlistentry>
 168         <term><command>revert <replaceable>LINK</replaceable></command></term>
 169
 170         <listitem><para>Revert the per-interface DNS configuration. If the DNS configuration is reverted all
 171         per-interface DNS setting are reset to their defaults, undoing all effects of <command>dns</command>,
 172         <command>domain</command>, <command>default-route</command>, <command>llmnr</command>,
 173         <command>mdns</command>, <command>dnssec</command>, <command>dnsovertls</command>,
 174         <command>nta</command>. Note that when a network interface disappears all configuration is lost
 175         automatically, an explicit reverting is not necessary in that case.</para></listitem>
 176       </varlistentry>
 177
 178       <xi:include href="systemctl.xml" xpointer="log-level" />
 179     </variablelist>
 180   </refsect1>
 181
 182   <refsect1>
 183     <title>Options</title>
 184     <variablelist>
 185       <varlistentry>
 186         <term><option>-4</option></term>
 187         <term><option>-6</option></term>
 188
 189         <listitem><para>By default, when resolving a hostname, both IPv4 and IPv6
 190         addresses are acquired. By specifying <option>-4</option> only IPv4 addresses are requested, by specifying
 191         <option>-6</option> only IPv6 addresses are requested.</para>
 192         </listitem>
 193       </varlistentry>
 194
 195       <varlistentry>
 196         <term><option>-i</option> <replaceable>INTERFACE</replaceable></term>
 197         <term><option>--interface=</option><replaceable>INTERFACE</replaceable></term>
 198
 199         <listitem><para>Specifies the network interface to execute the query on. This may either be specified as numeric
 200         interface index or as network interface string (e.g. <literal>en0</literal>). Note that this option has no
 201         effect if system-wide DNS configuration (as configured in <filename>/etc/resolv.conf</filename> or
 202         <filename>/etc/systemd/resolve.conf</filename>) in place of per-link configuration is used.</para></listitem>
 203       </varlistentry>
 204
 205       <varlistentry>
 206         <term><option>-p</option> <replaceable>PROTOCOL</replaceable></term>
 207         <term><option>--protocol=</option><replaceable>PROTOCOL</replaceable></term>
 208
 209         <listitem><para>Specifies the network protocol for the query. May be one of <literal>dns</literal>
 210         (i.e. classic unicast DNS), <literal>llmnr</literal> (<ulink
 211         url="https://tools.ietf.org/html/rfc4795">Link-Local Multicast Name Resolution</ulink>),
 212         <literal>llmnr-ipv4</literal>, <literal>llmnr-ipv6</literal> (LLMNR via the indicated underlying IP
 213         protocols), <literal>mdns</literal> (<ulink url="https://www.ietf.org/rfc/rfc6762.txt">Multicast DNS</ulink>),
 214         <literal>mdns-ipv4</literal>, <literal>mdns-ipv6</literal> (MDNS via the indicated underlying IP protocols).
 215         By default the lookup is done via all protocols suitable for the lookup. If used, limits the set of
 216         protocols that may be used. Use this option multiple times to enable resolving via multiple protocols at the
 217         same time. The setting <literal>llmnr</literal> is identical to specifying this switch once with
 218         <literal>llmnr-ipv4</literal> and once via <literal>llmnr-ipv6</literal>. Note that this option does not force
 219         the service to resolve the operation with the specified protocol, as that might require a suitable network
 220         interface and configuration.
 221         The special value <literal>help</literal> may be used to list known values.
 222         </para></listitem>
 223       </varlistentry>
 224
 225       <varlistentry>
 226         <term><option>-t</option> <replaceable>TYPE</replaceable></term>
 227         <term><option>--type=</option><replaceable>TYPE</replaceable></term>
 228         <term><option>-c</option> <replaceable>CLASS</replaceable></term>
 229         <term><option>--class=</option><replaceable>CLASS</replaceable></term>
 230
 231         <listitem><para>Specifies the DNS resource record type (e.g. A, AAAA, MX, …) and class (e.g. IN, ANY, …) to
 232         look up. If these options are used a DNS resource record set matching the specified class and type is
 233         requested. The class defaults to IN if only a type is specified.
 234         The special value <literal>help</literal> may be used to list known values.
 235         </para></listitem>
 236       </varlistentry>
 237
 238       <varlistentry>
 239         <term><option>--service-address=</option><replaceable>BOOL</replaceable></term>
 240
 241         <listitem><para>Takes a boolean parameter. If true (the default), when doing a service lookup with
 242         <option>--service</option> the hostnames contained in the SRV resource records are resolved as well.</para></listitem>
 243       </varlistentry>
 244
 245       <varlistentry>
 246         <term><option>--service-txt=</option><replaceable>BOOL</replaceable></term>
 247
 248         <listitem><para>Takes a boolean parameter. If true (the default), when doing a DNS-SD service lookup with
 249         <option>--service</option> the TXT service metadata record is resolved as well.</para></listitem>
 250       </varlistentry>
 251
 252       <varlistentry>
 253         <term><option>--cname=</option><replaceable>BOOL</replaceable></term>
 254
 255         <listitem><para>Takes a boolean parameter. If true (the default), DNS CNAME or DNAME redirections are
 256         followed. Otherwise, if a CNAME or DNAME record is encountered while resolving, an error is
 257         returned.</para></listitem>
 258       </varlistentry>
 259
 260       <varlistentry>
 261         <term><option>--search=</option><replaceable>BOOL</replaceable></term>
 262
 263         <listitem><para>Takes a boolean parameter. If true (the default), any specified single-label hostnames will be
 264         searched in the domains configured in the search domain list, if it is non-empty. Otherwise, the search domain
 265         logic is disabled.</para></listitem>
 266       </varlistentry>
 267
 268       <varlistentry>
 269         <term><option>--raw</option><optional>=payload|packet</optional></term>
 270
 271         <listitem><para>Dump the answer as binary data. If there is no argument or if the argument is
 272         <literal>payload</literal>, the payload of the packet is exported. If the argument is
 273         <literal>packet</literal>, the whole packet is dumped in wire format, prefixed by
 274         length specified as a little-endian 64-bit number. This format allows multiple packets
 275         to be dumped and unambiguously parsed.</para></listitem>
 276       </varlistentry>
 277
 278       <varlistentry>
 279         <term><option>--legend=</option><replaceable>BOOL</replaceable></term>
 280
 281         <listitem><para>Takes a boolean parameter. If true (the default), column headers and meta information about the
 282         query response are shown. Otherwise, this output is suppressed.</para></listitem>
 283       </varlistentry>
 284
 285       <xi:include href="standard-options.xml" xpointer="help" />
 286       <xi:include href="standard-options.xml" xpointer="version" />
 287       <xi:include href="standard-options.xml" xpointer="no-pager" />
 288     </variablelist>
 289   </refsect1>
 290
 291   <refsect1>
 292     <title>Compatibility with
 293     <citerefentry project="debian"><refentrytitle>resolvconf</refentrytitle><manvolnum>8</manvolnum></citerefentry></title>
 294
 295     <para><command>resolvectl</command> is a multi-call binary. When invoked as <literal>resolvconf</literal>
 296     (generally achieved by means of a symbolic link of this name to the <command>resolvectl</command> binary) it
 297     is run in a limited
 298     <citerefentry project="debian"><refentrytitle>resolvconf</refentrytitle><manvolnum>8</manvolnum></citerefentry>
 299     compatibility mode. It accepts mostly the same arguments and pushes all data into
 300     <citerefentry><refentrytitle>systemd-resolved.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
 301     similar to how <option>dns</option> and <option>domain</option> commands operate. Note that
 302     <command>systemd-resolved.service</command> is the only supported backend, which is different from other
 303     implementations of this command.</para>
 304
 305     <para><filename>/etc/resolv.conf</filename> will only be updated with servers added with this command
 306     when <filename>/etc/resolv.conf</filename> is a symlink to
 307     <filename>/run/systemd/resolve/resolv.conf</filename>, and not a static file. See the discussion of
 308     <filename>/etc/resolv.conf</filename> handling in
 309     <citerefentry><refentrytitle>systemd-resolved.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
 310     </para>
 311
 312     <para>Not all operations supported by other implementations are supported natively. Specifically:</para>
 313
 314     <variablelist>
 315       <varlistentry>
 316         <term><option>-a</option></term>
 317         <listitem><para>Registers per-interface DNS configuration data with
 318         <command>systemd-resolved</command>. Expects a network interface name as only command line argument. Reads
 319         <citerefentry><refentrytitle>resolv.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry> compatible DNS
 320         configuration data from its standard input. Relevant fields are <literal>nameserver</literal> and
 321         <literal>domain</literal>/<literal>search</literal>. This command is mostly identical to invoking
 322         <command>resolvectl</command> with a combination of <option>dns</option> and
 323         <option>domain</option> commands.</para></listitem>
 324       </varlistentry>
 325
 326       <varlistentry>
 327         <term><option>-d</option></term>
 328         <listitem><para>Unregisters per-interface DNS configuration data with <command>systemd-resolved</command>. This
 329         command is mostly identical to invoking <command>resolvectl revert</command>.</para></listitem>
 330       </varlistentry>
 331
 332       <varlistentry>
 333         <term><option>-f</option></term>
 334
 335         <listitem><para>When specified <option>-a</option> and <option>-d</option> will not complain about missing
 336         network interfaces and will silently execute no operation in that case.</para></listitem>
 337       </varlistentry>
 338
 339       <varlistentry>
 340         <term><option>-x</option></term>
 341
 342         <listitem><para>This switch for "exclusive" operation is supported only partially. It is mapped to an
 343         additional configured search domain of <literal>~.</literal> — i.e. ensures that DNS traffic is preferably
 344         routed to the DNS servers on this interface, unless there are other, more specific domains configured on other
 345         interfaces.</para></listitem>
 346       </varlistentry>
 347
 348       <varlistentry>
 349         <term><option>-m</option></term>
 350         <term><option>-p</option></term>
 351
 352         <listitem><para>These switches are not supported and are silently ignored.</para></listitem>
 353       </varlistentry>
 354
 355       <varlistentry>
 356         <term><option>-u</option></term>
 357         <term><option>-I</option></term>
 358         <term><option>-i</option></term>
 359         <term><option>-l</option></term>
 360         <term><option>-R</option></term>
 361         <term><option>-r</option></term>
 362         <term><option>-v</option></term>
 363         <term><option>-V</option></term>
 364         <term><option>--enable-updates</option></term>
 365         <term><option>--disable-updates</option></term>
 366         <term><option>--are-updates-enabled</option></term>
 367
 368         <listitem><para>These switches are not supported and the command will fail if used.</para></listitem>
 369       </varlistentry>
 370
 371     </variablelist>
 372
 373     <para>See
 374     <citerefentry project="debian"><refentrytitle>resolvconf</refentrytitle><manvolnum>8</manvolnum></citerefentry>
 375     for details on those command line options.</para>
 376   </refsect1>
 377
 378   <refsect1>
 379     <title>Examples</title>
 380
 381     <example>
 382       <title>Retrieve the addresses of the <literal>www.0pointer.net</literal> domain</title>
 383
 384       <programlisting>$ resolvectl query www.0pointer.net
 385 www.0pointer.net: 2a01:238:43ed:c300:10c3:bcf3:3266:da74
 386                   85.214.157.71
 387
 388 -- Information acquired via protocol DNS in 611.6ms.
 389 -- Data is authenticated: no
 390 </programlisting>
 391     </example>
 392
 393     <example>
 394       <title>Retrieve the domain of the <literal>85.214.157.71</literal> IP address</title>
 395
 396       <programlisting>$ resolvectl query 85.214.157.71
 397 85.214.157.71: gardel.0pointer.net
 398
 399 -- Information acquired via protocol DNS in 1.2997s.
 400 -- Data is authenticated: no
 401 </programlisting>
 402     </example>
 403
 404     <example>
 405       <title>Retrieve the MX record of the <literal>yahoo.com</literal> domain</title>
 406
 407       <programlisting>$ resolvectl --legend=no -t MX query yahoo.com
 408 yahoo.com. IN MX    1 mta7.am0.yahoodns.net
 409 yahoo.com. IN MX    1 mta6.am0.yahoodns.net
 410 yahoo.com. IN MX    1 mta5.am0.yahoodns.net
 411 </programlisting>
 412     </example>
 413
 414     <example>
 415       <title>Resolve an SRV service</title>
 416
 417       <programlisting>$ resolvectl service _xmpp-server._tcp gmail.com
 418 _xmpp-server._tcp/gmail.com: alt1.xmpp-server.l.google.com:5269 [priority=20, weight=0]
 419                              173.194.210.125
 420                              alt4.xmpp-server.l.google.com:5269 [priority=20, weight=0]
 421                              173.194.65.125
 422                              …
 423 </programlisting>
 424     </example>
 425
 426     <example>
 427       <title>Retrieve a PGP key</title>
 428
 429       <programlisting>$ resolvectl openpgp zbyszek@fedoraproject.org
 430 d08ee310438ca124a6149ea5cc21b6313b390dce485576eff96f8722._openpgpkey.fedoraproject.org. IN OPENPGPKEY
 431         mQINBFBHPMsBEACeInGYJCb+7TurKfb6wGyTottCDtiSJB310i37/6ZYoeIay/5soJjlMyf
 432         MFQ9T2XNT/0LM6gTa0MpC1st9LnzYTMsT6tzRly1D1UbVI6xw0g0vE5y2Cjk3xUwAynCsSs
 433         …
 434 </programlisting>
 435     </example>
 436
 437     <example>
 438       <title>Retrieve a TLS key (<literal>tcp</literal> and
 439       <literal>:443</literal> could be skipped)</title>
 440
 441       <programlisting>$ resolvectl tlsa tcp fedoraproject.org:443
 442 _443._tcp.fedoraproject.org IN TLSA 0 0 1 19400be5b7a31fb733917700789d2f0a2471c0c9d506c0e504c06c16d7cb17c0
 443         -- Cert. usage: CA constraint
 444         -- Selector: Full Certificate
 445         -- Matching type: SHA-256
 446 </programlisting>
 447     </example>
 448   </refsect1>
 449
 450   <refsect1>
 451     <title>See Also</title>
 452     <para>
 453       <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
 454       <citerefentry><refentrytitle>systemd-resolved.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
 455       <citerefentry><refentrytitle>systemd.dnssd</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 456       <citerefentry><refentrytitle>systemd-networkd.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
 457       <citerefentry><refentrytitle>resolvconf</refentrytitle><manvolnum>8</manvolnum></citerefentry>
 458     </para>
 459   </refsect1>
 460 </refentry>