man/resolvectl.xml

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