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>RRDOMAIN</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> --statistics</command>
  83     </cmdsynopsis>
  84
  85     <cmdsynopsis>
  86       <command>systemd-resolve</command>
  87       <arg choice="opt" rep="repeat">OPTIONS</arg>
  88       <command> --reset-statistics</command>
  89     </cmdsynopsis>
  90
  91   </refsynopsisdiv>
  92
  93   <refsect1>
  94     <title>Description</title>
  95
  96     <para><command>systemd-resolve</command> may be used to resolve domain names, IPv4 and IPv6 addresses, DNS resource
  97     records and services with the
  98     <citerefentry><refentrytitle>systemd-resolved.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>
  99     resolver service. By default, the specified list of parameters will be resolved as hostnames, retrieving their IPv4
 100     and IPv6 addresses. If the parameters specified are formatted as IPv4 or IPv6 operation the reverse operation is
 101     done, and a hostname is retrieved for the specified addresses.</para>
 102
 103     <para>The <option>--type=</option> switch may be used to specify a DNS resource record type (A, AAAA, SOA, MX, ...) in
 104     order to request a specific DNS resource record, instead of the address or reverse address lookups.
 105     The special value <literal>help</literal> may be used to list known values.</para>
 106
 107     <para>The <option>--service</option> switch may be used to resolve <ulink
 108     url="https://tools.ietf.org/html/rfc2782">SRV</ulink> and <ulink
 109     url="https://tools.ietf.org/html/rfc6763">DNS-SD</ulink> services (see below). In this mode, between one and three
 110     arguments are required. If three parameters are passed the first is assumed to be the DNS-SD service name, the
 111     second the SRV service type, and the third the domain to search in. In this case a full DNS-SD style SRV and TXT
 112     lookup is executed. If only two parameters are specified, the first is assumed to be the SRV service type, and the
 113     second the domain to look in. In this case no TXT RR is requested. Finally, if only one parameter is specified, it
 114     is assumed to be a domain name, that is already prefixed with an SRV type, and an SRV lookup is done (no
 115     TXT).</para>
 116
 117     <para>The <option>--statistics</option> switch may be used to show resolver statistics, including information about
 118     the number of succesful and failed DNSSEC validations.</para>
 119
 120     <para>The <option>--reset-statistics</option> may be used to reset various statistics counters maintained the
 121     resolver, including those shown in the <option>--statistics</option> output. This operation requires root
 122     privileges.</para>
 123   </refsect1>
 124
 125   <refsect1>
 126     <title>Options</title>
 127     <variablelist>
 128       <varlistentry>
 129         <term><option>-4</option></term>
 130         <term><option>-6</option></term>
 131
 132         <listitem><para>By default, when resolving a hostname, both IPv4 and IPv6
 133         addresses are acquired. By specifying <option>-4</option> only IPv4 addresses are requested, by specifying
 134         <option>-6</option> only IPv6 addresses are requested.</para>
 135         </listitem>
 136       </varlistentry>
 137
 138       <varlistentry>
 139         <term><option>-i</option> <replaceable>INTERFACE</replaceable></term>
 140         <term><option>--interface=</option><replaceable>INTERFACE</replaceable></term>
 141
 142         <listitem><para>Specifies the network interface to execute the query on. This may either be specified as numeric
 143         interface index or as network interface string (e.g. <literal>en0</literal>). Note that this option has no
 144         effect if system-wide DNS configuration (as configured in <filename>/etc/resolv.conf</filename> or
 145         <filename>/etc/systemd/resolve.conf</filename>) in place of per-link configuration is used.</para></listitem>
 146       </varlistentry>
 147
 148       <varlistentry>
 149         <term><option>-p</option> <replaceable>PROTOCOL</replaceable></term>
 150         <term><option>--protocol=</option><replaceable>PROTOCOL</replaceable></term>
 151
 152         <listitem><para>Specifies the network protocol for the query. May be one of <literal>dns</literal>
 153         (i.e. classic unicast DNS), <literal>llmnr</literal> (<ulink
 154         url="https://tools.ietf.org/html/rfc4795">Link-Local Multicast Name Resolution</ulink>),
 155         <literal>llmr-ipv4</literal>, <literal>llmnr-ipv6</literal> (LLMNR via the indicated underlying IP
 156         protocols). By default the lookup is done via all protocols suitable for the lookup. If used, limits the set of
 157         protocols that may be used. Use this option multiple times to enable resolving via multiple protocols at the
 158         same time. The setting <literal>llmnr</literal> is identical to specifying this switch once with
 159         <literal>llmnr-ipv4</literal> and once via <literal>llmnr-ipv6</literal>. Note that this option does not force
 160         the service to resolve the operation with the specified protocol, as that might require a suitable network
 161         interface and configuration.
 162         The special value <literal>help</literal> may be used to list known values.
 163         </para></listitem>
 164       </varlistentry>
 165
 166       <varlistentry>
 167         <term><option>-t</option> <replaceable>TYPE</replaceable></term>
 168         <term><option>--type=</option><replaceable>TYPE</replaceable></term>
 169         <term><option>-c</option> <replaceable>CLASS</replaceable></term>
 170         <term><option>--class=</option><replaceable>CLASS</replaceable></term>
 171
 172         <listitem><para>Specifies the DNS resource record type (e.g. A, AAAA, MX, …) and class (e.g. IN, ANY, …) to
 173         look up. If these options are used a DNS resource record set matching the specified class and type is
 174         requested. The class defaults to IN if only a type is specified.
 175         The special value <literal>help</literal> may be used to list known values.
 176         </para></listitem>
 177       </varlistentry>
 178
 179       <varlistentry>
 180         <term><option>--service</option></term>
 181
 182         <listitem><para>Enables service resolution. This enables DNS-SD and simple SRV service resolution, depending
 183         on the specified list of parameters (see above).</para></listitem>
 184       </varlistentry>
 185
 186       <varlistentry>
 187         <term><option>--service-address=</option><replaceable>BOOL</replaceable></term>
 188
 189         <listitem><para>Takes a boolean parameter. If true (the default), when doing a service lookup with
 190         <option>--service</option> the hostnames contained in the SRV resource records are resolved as well.</para></listitem>
 191       </varlistentry>
 192
 193       <varlistentry>
 194         <term><option>--service-txt=</option><replaceable>BOOL</replaceable></term>
 195
 196         <listitem><para>Takes a boolean parameter. If true (the default), when doing a DNS-SD service lookup with
 197         <option>--service</option> the TXT service metadata record is resolved as well.</para></listitem>
 198       </varlistentry>
 199
 200       <varlistentry>
 201         <term><option>--cname=</option><replaceable>BOOL</replaceable></term>
 202
 203         <listitem><para>Takes a boolean parameter. If true (the default), DNS CNAME or DNAME redirections are
 204         followed. Otherwise, if a CNAME or DNAME record is encountered while resolving, an error is
 205         returned.</para></listitem>
 206       </varlistentry>
 207
 208       <varlistentry>
 209         <term><option>--search=</option><replaceable>BOOL</replaceable></term>
 210
 211         <listitem><para>Takes a boolean parameter. If true (the default), any specified single-label hostnames will be
 212         searched in the domains configured in the search domain list, if it is non-empty. Otherwise, the search domain
 213         logic is disabled.</para></listitem>
 214       </varlistentry>
 215
 216       <varlistentry>
 217         <term><option>--legend=</option><replaceable>BOOL</replaceable></term>
 218
 219         <listitem><para>Takes a boolean parameter. If true (the default), column headers and meta information about the
 220         query response are shown. Otherwise, this output is suppressed.</para></listitem>
 221       </varlistentry>
 222
 223       <varlistentry>
 224         <term><option>--statistics</option></term>
 225
 226         <listitem><para>If specified general resolver statistics are shown, including information whether DNSSEC is
 227         enabled and available, as well as resolution and validation statistics.</para></listitem>
 228       </varlistentry>
 229
 230       <varlistentry>
 231         <term><option>--reset-statistics</option></term>
 232
 233         <listitem><para>Resets the statistics counters shown in <option>--statistics</option> to zero.</para></listitem>
 234       </varlistentry>
 235
 236       <xi:include href="standard-options.xml" xpointer="help" />
 237       <xi:include href="standard-options.xml" xpointer="version" />
 238     </variablelist>
 239   </refsect1>
 240
 241   <refsect1>
 242     <title>Examples</title>
 243
 244     <example>
 245       <title>Retrieve the addresses of the <literal>www.0pointer.net</literal> domain</title>
 246
 247       <programlisting>$ systemd-resolve www.0pointer.net</programlisting>
 248     </example>
 249
 250     <example>
 251       <title>Retrieve the domain of the <literal>85.214.157.71</literal> IP address</title>
 252
 253       <programlisting>$ systemd-resolve 85.214.157.71</programlisting>
 254     </example>
 255
 256     <example>
 257       <title>Retrieve the MX record of the <literal>0pointer.net</literal> domain</title>
 258
 259       <programlisting>$ systemd-resolve -t MX 0pointer.net</programlisting>
 260     </example>
 261
 262     <example>
 263       <title>Resolve an SRV service</title>
 264
 265       <programlisting>$ systemd-resolve --service _xmpp-server._tcp gmail.com</programlisting>
 266     </example>
 267
 268   </refsect1>
 269
 270   <refsect1>
 271     <title>See Also</title>
 272     <para>
 273       <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
 274       <citerefentry><refentrytitle>systemd-resolved.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>
 275     </para>
 276   </refsect1>
 277 </refentry>