man/systemd-resolve.xml

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  23
  24 <refentry id="systemd-resolve"
  25           xmlns:xi="http://www.w3.org/2001/XInclude">
  26
  27   <refentryinfo>
  28     <title>systemd-resolve</title>
  29     <productname>systemd</productname>
  30
  31     <authorgroup>
  32       <author>
  33         <contrib>Developer</contrib>
  34         <firstname>Lennart</firstname>
  35         <surname>Poettering</surname>
  36         <email>lennart@poettering.net</email>
  37       </author>
  38     </authorgroup>
  39   </refentryinfo>
  40
  41   <refmeta>
  42     <refentrytitle>systemd-resolve</refentrytitle>
  43     <manvolnum>1</manvolnum>
  44   </refmeta>
  45
  46   <refnamediv>
  47     <refname>systemd-resolve</refname>
  48     <refpurpose>Resolve domain names, IPV4 and IPv6 addresses, DNS resource records, and services</refpurpose>
  49   </refnamediv>
  50
  51   <refsynopsisdiv>
  52     <cmdsynopsis>
  53       <command>systemd-resolve</command>
  54       <arg choice="opt" rep="repeat">OPTIONS</arg>
  55       <arg choice="plain" rep="repeat"><replaceable>HOSTNAME</replaceable></arg>
  56     </cmdsynopsis>
  57
  58     <cmdsynopsis>
  59       <command>systemd-resolve</command>
  60       <arg choice="opt" rep="repeat">OPTIONS</arg>
  61       <arg choice="plain" rep="repeat"><replaceable>ADDRESS</replaceable></arg>
  62     </cmdsynopsis>
  63
  64     <cmdsynopsis>
  65       <command>systemd-resolve</command>
  66       <arg choice="opt" rep="repeat">OPTIONS</arg>
  67       <command> --type=<replaceable>TYPE</replaceable></command>
  68       <arg choice="plain" rep="repeat"><replaceable>DOMAIN</replaceable></arg>
  69     </cmdsynopsis>
  70
  71     <cmdsynopsis>
  72       <command>systemd-resolve</command>
  73       <arg choice="opt" rep="repeat">OPTIONS</arg>
  74       <command> --service</command>
  75       <arg choice="plain"><arg choice="opt"><arg choice="opt"><replaceable>NAME</replaceable></arg>
  76       <replaceable>TYPE</replaceable></arg> <replaceable>DOMAIN</replaceable></arg>
  77     </cmdsynopsis>
  78
  79     <cmdsynopsis>
  80       <command>systemd-resolve</command>
  81       <arg choice="opt" rep="repeat">OPTIONS</arg>
  82       <command> --openpgp</command>
  83       <arg choice="plain"><replaceable>USER@DOMAIN</replaceable></arg>
  84     </cmdsynopsis>
  85
  86     <cmdsynopsis>
  87       <command>systemd-resolve</command>
  88       <arg choice="opt" rep="repeat">OPTIONS</arg>
  89       <command> --tlsa</command>
  90       <arg choice="plain"><replaceable>DOMAIN<optional>:PORT</optional></replaceable></arg>
  91     </cmdsynopsis>
  92
  93     <cmdsynopsis>
  94       <command>systemd-resolve</command>
  95       <arg choice="opt" rep="repeat">OPTIONS</arg>
  96       <command> --statistics</command>
  97     </cmdsynopsis>
  98
  99     <cmdsynopsis>
 100       <command>systemd-resolve</command>
 101       <arg choice="opt" rep="repeat">OPTIONS</arg>
 102       <command> --reset-statistics</command>
 103     </cmdsynopsis>
 104
 105   </refsynopsisdiv>
 106
 107   <refsect1>
 108     <title>Description</title>
 109
 110     <para><command>systemd-resolve</command> may be used to resolve domain names, IPv4 and IPv6 addresses, DNS resource
 111     records and services with the
 112     <citerefentry><refentrytitle>systemd-resolved.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>
 113     resolver service. By default, the specified list of parameters will be resolved as hostnames, retrieving their IPv4
 114     and IPv6 addresses. If the parameters specified are formatted as IPv4 or IPv6 operation the reverse operation is
 115     done, and a hostname is retrieved for the specified addresses.</para>
 116
 117     <para>The <option>--type=</option> switch may be used to specify a DNS resource record type (A, AAAA, SOA, MX, ...) in
 118     order to request a specific DNS resource record, instead of the address or reverse address lookups.
 119     The special value <literal>help</literal> may be used to list known values.</para>
 120
 121     <para>The <option>--service</option> switch may be used to resolve <ulink
 122     url="https://tools.ietf.org/html/rfc2782">SRV</ulink> and <ulink
 123     url="https://tools.ietf.org/html/rfc6763">DNS-SD</ulink> services (see below). In this mode, between one and three
 124     arguments are required. If three parameters are passed the first is assumed to be the DNS-SD service name, the
 125     second the SRV service type, and the third the domain to search in. In this case a full DNS-SD style SRV and TXT
 126     lookup is executed. If only two parameters are specified, the first is assumed to be the SRV service type, and the
 127     second the domain to look in. In this case no TXT RR is requested. Finally, if only one parameter is specified, it
 128     is assumed to be a domain name, that is already prefixed with an SRV type, and an SRV lookup is done (no
 129     TXT).</para>
 130
 131     <para>The <option>--openpgp</option> switch may be used to query PGP keys stored as
 132     <ulink url="https://tools.ietf.org/html/draft-wouters-dane-openpgp-02">OPENPGPKEY</ulink> resource records.
 133     When this option is specified one or more e-mail address must be specified.</para>
 134
 135     <para>The <option>--tlsa</option> switch maybe be used to query TLS public
 136     keys stored as
 137     <ulink url="https://tools.ietf.org/html/rfc6698">TLSA</ulink> resource records.
 138     When this option is specified one or more domain names must be specified.</para>
 139
 140     <para>The <option>--statistics</option> switch may be used to show resolver statistics, including information about
 141     the number of successful and failed DNSSEC validations.</para>
 142
 143     <para>The <option>--reset-statistics</option> may be used to reset various statistics counters maintained the
 144     resolver, including those shown in the <option>--statistics</option> output. This operation requires root
 145     privileges.</para>
 146   </refsect1>
 147
 148   <refsect1>
 149     <title>Options</title>
 150     <variablelist>
 151       <varlistentry>
 152         <term><option>-4</option></term>
 153         <term><option>-6</option></term>
 154
 155         <listitem><para>By default, when resolving a hostname, both IPv4 and IPv6
 156         addresses are acquired. By specifying <option>-4</option> only IPv4 addresses are requested, by specifying
 157         <option>-6</option> only IPv6 addresses are requested.</para>
 158         </listitem>
 159       </varlistentry>
 160
 161       <varlistentry>
 162         <term><option>-i</option> <replaceable>INTERFACE</replaceable></term>
 163         <term><option>--interface=</option><replaceable>INTERFACE</replaceable></term>
 164
 165         <listitem><para>Specifies the network interface to execute the query on. This may either be specified as numeric
 166         interface index or as network interface string (e.g. <literal>en0</literal>). Note that this option has no
 167         effect if system-wide DNS configuration (as configured in <filename>/etc/resolv.conf</filename> or
 168         <filename>/etc/systemd/resolve.conf</filename>) in place of per-link configuration is used.</para></listitem>
 169       </varlistentry>
 170
 171       <varlistentry>
 172         <term><option>-p</option> <replaceable>PROTOCOL</replaceable></term>
 173         <term><option>--protocol=</option><replaceable>PROTOCOL</replaceable></term>
 174
 175         <listitem><para>Specifies the network protocol for the query. May be one of <literal>dns</literal>
 176         (i.e. classic unicast DNS), <literal>llmnr</literal> (<ulink
 177         url="https://tools.ietf.org/html/rfc4795">Link-Local Multicast Name Resolution</ulink>),
 178         <literal>llmnr-ipv4</literal>, <literal>llmnr-ipv6</literal> (LLMNR via the indicated underlying IP
 179         protocols). By default the lookup is done via all protocols suitable for the lookup. If used, limits the set of
 180         protocols that may be used. Use this option multiple times to enable resolving via multiple protocols at the
 181         same time. The setting <literal>llmnr</literal> is identical to specifying this switch once with
 182         <literal>llmnr-ipv4</literal> and once via <literal>llmnr-ipv6</literal>. Note that this option does not force
 183         the service to resolve the operation with the specified protocol, as that might require a suitable network
 184         interface and configuration.
 185         The special value <literal>help</literal> may be used to list known values.
 186         </para></listitem>
 187       </varlistentry>
 188
 189       <varlistentry>
 190         <term><option>-t</option> <replaceable>TYPE</replaceable></term>
 191         <term><option>--type=</option><replaceable>TYPE</replaceable></term>
 192         <term><option>-c</option> <replaceable>CLASS</replaceable></term>
 193         <term><option>--class=</option><replaceable>CLASS</replaceable></term>
 194
 195         <listitem><para>Specifies the DNS resource record type (e.g. A, AAAA, MX, …) and class (e.g. IN, ANY, …) to
 196         look up. If these options are used a DNS resource record set matching the specified class and type is
 197         requested. The class defaults to IN if only a type is specified.
 198         The special value <literal>help</literal> may be used to list known values.
 199         </para></listitem>
 200       </varlistentry>
 201
 202       <varlistentry>
 203         <term><option>--service</option></term>
 204
 205         <listitem><para>Enables service resolution. This enables DNS-SD and simple SRV service resolution, depending
 206         on the specified list of parameters (see above).</para></listitem>
 207       </varlistentry>
 208
 209       <varlistentry>
 210         <term><option>--service-address=</option><replaceable>BOOL</replaceable></term>
 211
 212         <listitem><para>Takes a boolean parameter. If true (the default), when doing a service lookup with
 213         <option>--service</option> the hostnames contained in the SRV resource records are resolved as well.</para></listitem>
 214       </varlistentry>
 215
 216       <varlistentry>
 217         <term><option>--service-txt=</option><replaceable>BOOL</replaceable></term>
 218
 219         <listitem><para>Takes a boolean parameter. If true (the default), when doing a DNS-SD service lookup with
 220         <option>--service</option> the TXT service metadata record is resolved as well.</para></listitem>
 221       </varlistentry>
 222
 223       <varlistentry>
 224         <term><option>--openpgp</option></term>
 225
 226         <listitem><para>Enables OPENPGPKEY resource record resolution (see above). Specified e-mail
 227         addresses are converted to the corresponding DNS domain name, and any OPENPGPKEY keys are
 228         printed.</para></listitem>
 229       </varlistentry>
 230
 231       <varlistentry>
 232         <term><option>--tlsa</option></term>
 233
 234         <listitem><para>Enables TLSA resource record resolution (see above).
 235         A query will be performed for each of the specified names prefixed with
 236         the port and family
 237         (<literal>_<replaceable>port</replaceable>._<replaceable>family</replaceable>.<replaceable>domain</replaceable></literal>).
 238         The port number may be specified after a colon
 239         (<literal>:</literal>), otherwise <constant>443</constant> will be used
 240         by default. The family may be specified as an argument after
 241         <option>--tlsa</option>, otherwise <constant>tcp</constant> will be
 242         used.</para></listitem>
 243       </varlistentry>
 244
 245       <varlistentry>
 246         <term><option>--cname=</option><replaceable>BOOL</replaceable></term>
 247
 248         <listitem><para>Takes a boolean parameter. If true (the default), DNS CNAME or DNAME redirections are
 249         followed. Otherwise, if a CNAME or DNAME record is encountered while resolving, an error is
 250         returned.</para></listitem>
 251       </varlistentry>
 252
 253       <varlistentry>
 254         <term><option>--search=</option><replaceable>BOOL</replaceable></term>
 255
 256         <listitem><para>Takes a boolean parameter. If true (the default), any specified single-label hostnames will be
 257         searched in the domains configured in the search domain list, if it is non-empty. Otherwise, the search domain
 258         logic is disabled.</para></listitem>
 259       </varlistentry>
 260
 261       <varlistentry>
 262         <term><option>--raw</option><optional>=payload|packet</optional></term>
 263
 264         <listitem><para>Dump the answer as binary data. If there is no argument or if the argument is
 265         <literal>payload</literal>, the payload of the packet is exported. If the argument is
 266         <literal>packet</literal>, the whole packet is dumped in wire format, prefixed by
 267         length specified as a little-endian 64-bit number. This format allows multiple packets
 268         to be dumped and unambigously parsed.</para></listitem>
 269       </varlistentry>
 270
 271       <varlistentry>
 272         <term><option>--legend=</option><replaceable>BOOL</replaceable></term>
 273
 274         <listitem><para>Takes a boolean parameter. If true (the default), column headers and meta information about the
 275         query response are shown. Otherwise, this output is suppressed.</para></listitem>
 276       </varlistentry>
 277
 278       <varlistentry>
 279         <term><option>--statistics</option></term>
 280
 281         <listitem><para>If specified general resolver statistics are shown, including information whether DNSSEC is
 282         enabled and available, as well as resolution and validation statistics.</para></listitem>
 283       </varlistentry>
 284
 285       <varlistentry>
 286         <term><option>--reset-statistics</option></term>
 287
 288         <listitem><para>Resets the statistics counters shown in <option>--statistics</option> to zero.</para></listitem>
 289       </varlistentry>
 290
 291       <xi:include href="standard-options.xml" xpointer="help" />
 292       <xi:include href="standard-options.xml" xpointer="version" />
 293     </variablelist>
 294   </refsect1>
 295
 296   <refsect1>
 297     <title>Examples</title>
 298
 299     <example>
 300       <title>Retrieve the addresses of the <literal>www.0pointer.net</literal> domain</title>
 301
 302       <programlisting>$ systemd-resolve www.0pointer.net
 303 www.0pointer.net: 2a01:238:43ed:c300:10c3:bcf3:3266:da74
 304                   85.214.157.71
 305
 306 -- Information acquired via protocol DNS in 611.6ms.
 307 -- Data is authenticated: no
 308 </programlisting>
 309     </example>
 310
 311     <example>
 312       <title>Retrieve the domain of the <literal>85.214.157.71</literal> IP address</title>
 313
 314       <programlisting>$ systemd-resolve 85.214.157.71
 315 85.214.157.71: gardel.0pointer.net
 316
 317 -- Information acquired via protocol DNS in 1.2997s.
 318 -- Data is authenticated: no
 319 </programlisting>
 320     </example>
 321
 322     <example>
 323       <title>Retrieve the MX record of the <literal>0pointer.net</literal> domain</title>
 324
 325       <programlisting>$ systemd-resolve -t MX yahoo.com --legend=no
 326 yahoo.com. IN MX    1 mta7.am0.yahoodns.net
 327 yahoo.com. IN MX    1 mta6.am0.yahoodns.net
 328 yahoo.com. IN MX    1 mta5.am0.yahoodns.net
 329 </programlisting>
 330     </example>
 331
 332     <example>
 333       <title>Resolve an SRV service</title>
 334
 335       <programlisting>$ systemd-resolve --service _xmpp-server._tcp gmail.com
 336 _xmpp-server._tcp/gmail.com: alt1.xmpp-server.l.google.com:5269 [priority=20, weight=0]
 337                              173.194.210.125
 338                              alt4.xmpp-server.l.google.com:5269 [priority=20, weight=0]
 339                              173.194.65.125
 340                              ...
 341 </programlisting>
 342     </example>
 343
 344     <example>
 345       <title>Retrieve a PGP key</title>
 346
 347       <programlisting>$ systemd-resolve --openpgp zbyszek@fedoraproject.org
 348 d08ee310438ca124a6149ea5cc21b6313b390dce485576eff96f8722._openpgpkey.fedoraproject.org. IN OPENPGPKEY
 349         mQINBFBHPMsBEACeInGYJCb+7TurKfb6wGyTottCDtiSJB310i37/6ZYoeIay/5soJjlMyf
 350         MFQ9T2XNT/0LM6gTa0MpC1st9LnzYTMsT6tzRly1D1UbVI6xw0g0vE5y2Cjk3xUwAynCsSs
 351         ...
 352 </programlisting>
 353     </example>
 354
 355     <example>
 356       <title>Retrieve a TLS key (<literal>=tcp</literal> and
 357       <literal>:443</literal> could be skipped)</title>
 358
 359       <programlisting>$ systemd-resolve --tlsa=tcp fedoraproject.org:443
 360 _443._tcp.fedoraproject.org IN TLSA 0 0 1 19400be5b7a31fb733917700789d2f0a2471c0c9d506c0e504c06c16d7cb17c0
 361         -- Cert. usage: CA constraint
 362         -- Selector: Full Certificate
 363         -- Matching type: SHA-256
 364 </programlisting>
 365     </example>
 366   </refsect1>
 367
 368   <refsect1>
 369     <title>See Also</title>
 370     <para>
 371       <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
 372       <citerefentry><refentrytitle>systemd-resolved.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>
 373     </para>
 374   </refsect1>
 375 </refentry>