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-or-later -->
   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. Each address can optionally take a port number
 149           separated with <literal>:</literal>, a network interface name or index separated with
 150           <literal>%</literal>, and a Server Name Indication (SNI) separated with <literal>#</literal>. When
 151           IPv6 address is specified with a port number, then the address must be in the square brackets. That
 152           is, the acceptable full formats are <literal>111.222.333.444:9953%ifname#example.com</literal> for
 153           IPv4 and <literal>[1111:2222::3333]:9953%ifname#example.com</literal> for IPv6. The
 154           <command>domain</command> command expects valid DNS domains, possibly prefixed with
 155           <literal>~</literal>, and configures a per-interface search or route-only domain. The
 156           <command>default-route</command> command expects a boolean parameter, and configures whether the
 157           link may be used as default route for DNS lookups, i.e. if it is suitable for lookups on domains no
 158           other link explicitly is configured for. The <command>llmnr</command>, <command>mdns</command>,
 159           <command>dnssec</command> and <command>dnsovertls</command> commands may be used to configure the
 160           per-interface LLMNR, MulticastDNS, DNSSEC and DNSOverTLS settings. Finally, <command>nta</command>
 161           command may be used to configure additional per-interface DNSSEC NTA domains.</para>
 162
 163           <para>Commands <command>dns</command>, <command>domain</command> and <command>nta</command> can take
 164           a single empty string argument to clear their respective value lists.</para>
 165
 166           <para>For details about these settings, their possible values and their effect, see the
 167           corresponding settings in
 168           <citerefentry><refentrytitle>systemd.network</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para>
 169         </listitem>
 170       </varlistentry>
 171
 172       <varlistentry>
 173         <term><command>revert <replaceable>LINK</replaceable></command></term>
 174
 175         <listitem><para>Revert the per-interface DNS configuration. If the DNS configuration is reverted all
 176         per-interface DNS setting are reset to their defaults, undoing all effects of <command>dns</command>,
 177         <command>domain</command>, <command>default-route</command>, <command>llmnr</command>,
 178         <command>mdns</command>, <command>dnssec</command>, <command>dnsovertls</command>,
 179         <command>nta</command>. Note that when a network interface disappears all configuration is lost
 180         automatically, an explicit reverting is not necessary in that case.</para></listitem>
 181       </varlistentry>
 182
 183       <xi:include href="systemctl.xml" xpointer="log-level" />
 184     </variablelist>
 185   </refsect1>
 186
 187   <refsect1>
 188     <title>Options</title>
 189     <variablelist>
 190       <varlistentry>
 191         <term><option>-4</option></term>
 192         <term><option>-6</option></term>
 193
 194         <listitem><para>By default, when resolving a hostname, both IPv4 and IPv6
 195         addresses are acquired. By specifying <option>-4</option> only IPv4 addresses are requested, by specifying
 196         <option>-6</option> only IPv6 addresses are requested.</para>
 197         </listitem>
 198       </varlistentry>
 199
 200       <varlistentry>
 201         <term><option>-i</option> <replaceable>INTERFACE</replaceable></term>
 202         <term><option>--interface=</option><replaceable>INTERFACE</replaceable></term>
 203
 204         <listitem><para>Specifies the network interface to execute the query on. This may either be specified as numeric
 205         interface index or as network interface string (e.g. <literal>en0</literal>). Note that this option has no
 206         effect if system-wide DNS configuration (as configured in <filename>/etc/resolv.conf</filename> or
 207         <filename>/etc/systemd/resolve.conf</filename>) in place of per-link configuration is used.</para></listitem>
 208       </varlistentry>
 209
 210       <varlistentry>
 211         <term><option>-p</option> <replaceable>PROTOCOL</replaceable></term>
 212         <term><option>--protocol=</option><replaceable>PROTOCOL</replaceable></term>
 213
 214         <listitem><para>Specifies the network protocol for the query. May be one of <literal>dns</literal>
 215         (i.e. classic unicast DNS), <literal>llmnr</literal> (<ulink
 216         url="https://tools.ietf.org/html/rfc4795">Link-Local Multicast Name Resolution</ulink>),
 217         <literal>llmnr-ipv4</literal>, <literal>llmnr-ipv6</literal> (LLMNR via the indicated underlying IP
 218         protocols), <literal>mdns</literal> (<ulink url="https://www.ietf.org/rfc/rfc6762.txt">Multicast DNS</ulink>),
 219         <literal>mdns-ipv4</literal>, <literal>mdns-ipv6</literal> (MDNS via the indicated underlying IP protocols).
 220         By default the lookup is done via all protocols suitable for the lookup. If used, limits the set of
 221         protocols that may be used. Use this option multiple times to enable resolving via multiple protocols at the
 222         same time. The setting <literal>llmnr</literal> is identical to specifying this switch once with
 223         <literal>llmnr-ipv4</literal> and once via <literal>llmnr-ipv6</literal>. Note that this option does not force
 224         the service to resolve the operation with the specified protocol, as that might require a suitable network
 225         interface and configuration.
 226         The special value <literal>help</literal> may be used to list known values.
 227         </para></listitem>
 228       </varlistentry>
 229
 230       <varlistentry>
 231         <term><option>-t</option> <replaceable>TYPE</replaceable></term>
 232         <term><option>--type=</option><replaceable>TYPE</replaceable></term>
 233         <term><option>-c</option> <replaceable>CLASS</replaceable></term>
 234         <term><option>--class=</option><replaceable>CLASS</replaceable></term>
 235
 236         <listitem><para>Specifies the DNS resource record type (e.g. A, AAAA, MX, …) and class (e.g. IN, ANY, …) to
 237         look up. If these options are used a DNS resource record set matching the specified class and type is
 238         requested. The class defaults to IN if only a type is specified.
 239         The special value <literal>help</literal> may be used to list known values.
 240         </para></listitem>
 241       </varlistentry>
 242
 243       <varlistentry>
 244         <term><option>--service-address=</option><replaceable>BOOL</replaceable></term>
 245
 246         <listitem><para>Takes a boolean parameter. If true (the default), when doing a service lookup with
 247         <option>--service</option> the hostnames contained in the SRV resource records are resolved as well.</para></listitem>
 248       </varlistentry>
 249
 250       <varlistentry>
 251         <term><option>--service-txt=</option><replaceable>BOOL</replaceable></term>
 252
 253         <listitem><para>Takes a boolean parameter. If true (the default), when doing a DNS-SD service lookup with
 254         <option>--service</option> the TXT service metadata record is resolved as well.</para></listitem>
 255       </varlistentry>
 256
 257       <varlistentry>
 258         <term><option>--cname=</option><replaceable>BOOL</replaceable></term>
 259
 260         <listitem><para>Takes a boolean parameter. If true (the default), DNS CNAME or DNAME redirections are
 261         followed. Otherwise, if a CNAME or DNAME record is encountered while resolving, an error is
 262         returned.</para></listitem>
 263       </varlistentry>
 264
 265       <varlistentry>
 266         <term><option>--search=</option><replaceable>BOOL</replaceable></term>
 267
 268         <listitem><para>Takes a boolean parameter. If true (the default), any specified single-label hostnames will be
 269         searched in the domains configured in the search domain list, if it is non-empty. Otherwise, the search domain
 270         logic is disabled.</para></listitem>
 271       </varlistentry>
 272
 273       <varlistentry>
 274         <term><option>--raw</option><optional>=payload|packet</optional></term>
 275
 276         <listitem><para>Dump the answer as binary data. If there is no argument or if the argument is
 277         <literal>payload</literal>, the payload of the packet is exported. If the argument is
 278         <literal>packet</literal>, the whole packet is dumped in wire format, prefixed by
 279         length specified as a little-endian 64-bit number. This format allows multiple packets
 280         to be dumped and unambiguously parsed.</para></listitem>
 281       </varlistentry>
 282
 283       <varlistentry>
 284         <term><option>--legend=</option><replaceable>BOOL</replaceable></term>
 285
 286         <listitem><para>Takes a boolean parameter. If true (the default), column headers and meta information about the
 287         query response are shown. Otherwise, this output is suppressed.</para></listitem>
 288       </varlistentry>
 289
 290       <xi:include href="standard-options.xml" xpointer="help" />
 291       <xi:include href="standard-options.xml" xpointer="version" />
 292       <xi:include href="standard-options.xml" xpointer="no-pager" />
 293     </variablelist>
 294   </refsect1>
 295
 296   <refsect1>
 297     <title>Compatibility with
 298     <citerefentry project="debian"><refentrytitle>resolvconf</refentrytitle><manvolnum>8</manvolnum></citerefentry></title>
 299
 300     <para><command>resolvectl</command> is a multi-call binary. When invoked as <literal>resolvconf</literal>
 301     (generally achieved by means of a symbolic link of this name to the <command>resolvectl</command> binary) it
 302     is run in a limited
 303     <citerefentry project="debian"><refentrytitle>resolvconf</refentrytitle><manvolnum>8</manvolnum></citerefentry>
 304     compatibility mode. It accepts mostly the same arguments and pushes all data into
 305     <citerefentry><refentrytitle>systemd-resolved.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
 306     similar to how <option>dns</option> and <option>domain</option> commands operate. Note that
 307     <command>systemd-resolved.service</command> is the only supported backend, which is different from other
 308     implementations of this command.</para>
 309
 310     <para><filename>/etc/resolv.conf</filename> will only be updated with servers added with this command
 311     when <filename>/etc/resolv.conf</filename> is a symlink to
 312     <filename>/run/systemd/resolve/resolv.conf</filename>, and not a static file. See the discussion of
 313     <filename>/etc/resolv.conf</filename> handling in
 314     <citerefentry><refentrytitle>systemd-resolved.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
 315     </para>
 316
 317     <para>Not all operations supported by other implementations are supported natively. Specifically:</para>
 318
 319     <variablelist>
 320       <varlistentry>
 321         <term><option>-a</option></term>
 322         <listitem><para>Registers per-interface DNS configuration data with
 323         <command>systemd-resolved</command>. Expects a network interface name as only command line argument. Reads
 324         <citerefentry project='man-pages'><refentrytitle>resolv.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>-compatible
 325         DNS configuration data from its standard input. Relevant fields are <literal>nameserver</literal> and
 326         <literal>domain</literal>/<literal>search</literal>. This command is mostly identical to invoking
 327         <command>resolvectl</command> with a combination of <option>dns</option> and <option>domain</option>
 328         commands.</para></listitem>
 329       </varlistentry>
 330
 331       <varlistentry>
 332         <term><option>-d</option></term>
 333         <listitem><para>Unregisters per-interface DNS configuration data with <command>systemd-resolved</command>. This
 334         command is mostly identical to invoking <command>resolvectl revert</command>.</para></listitem>
 335       </varlistentry>
 336
 337       <varlistentry>
 338         <term><option>-f</option></term>
 339
 340         <listitem><para>When specified <option>-a</option> and <option>-d</option> will not complain about missing
 341         network interfaces and will silently execute no operation in that case.</para></listitem>
 342       </varlistentry>
 343
 344       <varlistentry>
 345         <term><option>-x</option></term>
 346
 347         <listitem><para>This switch for "exclusive" operation is supported only partially. It is mapped to an
 348         additional configured search domain of <literal>~.</literal> — i.e. ensures that DNS traffic is preferably
 349         routed to the DNS servers on this interface, unless there are other, more specific domains configured on other
 350         interfaces.</para></listitem>
 351       </varlistentry>
 352
 353       <varlistentry>
 354         <term><option>-m</option></term>
 355         <term><option>-p</option></term>
 356
 357         <listitem><para>These switches are not supported and are silently ignored.</para></listitem>
 358       </varlistentry>
 359
 360       <varlistentry>
 361         <term><option>-u</option></term>
 362         <term><option>-I</option></term>
 363         <term><option>-i</option></term>
 364         <term><option>-l</option></term>
 365         <term><option>-R</option></term>
 366         <term><option>-r</option></term>
 367         <term><option>-v</option></term>
 368         <term><option>-V</option></term>
 369         <term><option>--enable-updates</option></term>
 370         <term><option>--disable-updates</option></term>
 371         <term><option>--are-updates-enabled</option></term>
 372
 373         <listitem><para>These switches are not supported and the command will fail if used.</para></listitem>
 374       </varlistentry>
 375
 376     </variablelist>
 377
 378     <para>See
 379     <citerefentry project="debian"><refentrytitle>resolvconf</refentrytitle><manvolnum>8</manvolnum></citerefentry>
 380     for details on those command line options.</para>
 381   </refsect1>
 382
 383   <refsect1>
 384     <title>Examples</title>
 385
 386     <example>
 387       <title>Retrieve the addresses of the <literal>www.0pointer.net</literal> domain</title>
 388
 389       <programlisting>$ resolvectl query www.0pointer.net
 390 www.0pointer.net: 2a01:238:43ed:c300:10c3:bcf3:3266:da74
 391                   85.214.157.71
 392
 393 -- Information acquired via protocol DNS in 611.6ms.
 394 -- Data is authenticated: no
 395 </programlisting>
 396     </example>
 397
 398     <example>
 399       <title>Retrieve the domain of the <literal>85.214.157.71</literal> IP address</title>
 400
 401       <programlisting>$ resolvectl query 85.214.157.71
 402 85.214.157.71: gardel.0pointer.net
 403
 404 -- Information acquired via protocol DNS in 1.2997s.
 405 -- Data is authenticated: no
 406 </programlisting>
 407     </example>
 408
 409     <example>
 410       <title>Retrieve the MX record of the <literal>yahoo.com</literal> domain</title>
 411
 412       <programlisting>$ resolvectl --legend=no -t MX query yahoo.com
 413 yahoo.com. IN MX    1 mta7.am0.yahoodns.net
 414 yahoo.com. IN MX    1 mta6.am0.yahoodns.net
 415 yahoo.com. IN MX    1 mta5.am0.yahoodns.net
 416 </programlisting>
 417     </example>
 418
 419     <example>
 420       <title>Resolve an SRV service</title>
 421
 422       <programlisting>$ resolvectl service _xmpp-server._tcp gmail.com
 423 _xmpp-server._tcp/gmail.com: alt1.xmpp-server.l.google.com:5269 [priority=20, weight=0]
 424                              173.194.210.125
 425                              alt4.xmpp-server.l.google.com:5269 [priority=20, weight=0]
 426                              173.194.65.125
 427                              …
 428 </programlisting>
 429     </example>
 430
 431     <example>
 432       <title>Retrieve a PGP key</title>
 433
 434       <programlisting>$ resolvectl openpgp zbyszek@fedoraproject.org
 435 d08ee310438ca124a6149ea5cc21b6313b390dce485576eff96f8722._openpgpkey.fedoraproject.org. IN OPENPGPKEY
 436         mQINBFBHPMsBEACeInGYJCb+7TurKfb6wGyTottCDtiSJB310i37/6ZYoeIay/5soJjlMyf
 437         MFQ9T2XNT/0LM6gTa0MpC1st9LnzYTMsT6tzRly1D1UbVI6xw0g0vE5y2Cjk3xUwAynCsSs
 438         …
 439 </programlisting>
 440     </example>
 441
 442     <example>
 443       <title>Retrieve a TLS key (<literal>tcp</literal> and
 444       <literal>:443</literal> could be skipped)</title>
 445
 446       <programlisting>$ resolvectl tlsa tcp fedoraproject.org:443
 447 _443._tcp.fedoraproject.org IN TLSA 0 0 1 19400be5b7a31fb733917700789d2f0a2471c0c9d506c0e504c06c16d7cb17c0
 448         -- Cert. usage: CA constraint
 449         -- Selector: Full Certificate
 450         -- Matching type: SHA-256
 451 </programlisting>
 452     </example>
 453   </refsect1>
 454
 455   <refsect1>
 456     <title>See Also</title>
 457     <para>
 458       <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
 459       <citerefentry><refentrytitle>systemd-resolved.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
 460       <citerefentry><refentrytitle>systemd.dnssd</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 461       <citerefentry><refentrytitle>systemd-networkd.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
 462       <citerefentry><refentrytitle>resolvconf</refentrytitle><manvolnum>8</manvolnum></citerefentry>
 463     </para>
 464   </refsect1>
 465 </refentry>