[thirdparty/systemd.git] / man / systemd.dnssd.xml

<?xml version='1.0'?> <!--*- Mode: nxml; nxml-child-indent: 2; indent-tabs-mode: nil -*-->
<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
  "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">

<!--
  This file is part of systemd.

  Copyright 2017 Dmitry Rozhkov
-->

<refentry id="systemd.dnssd" conditional='ENABLE_RESOLVE'>

  <refentryinfo>
    <title>systemd.dnssd</title>
    <productname>systemd</productname>

    <authorgroup>
      <author>
        <contrib>Developer</contrib>
        <firstname>Dmitry</firstname>
        <surname>Rozhkov</surname>
        <email>dmitry.rozhkov@intel.com</email>
      </author>
    </authorgroup>
  </refentryinfo>

  <refmeta>
    <refentrytitle>systemd.dnssd</refentrytitle>
    <manvolnum>5</manvolnum>
  </refmeta>

  <refnamediv>
    <refname>systemd.dnssd</refname>
    <refpurpose>DNS-SD configuration</refpurpose>
  </refnamediv>

  <refsynopsisdiv>
    <para><filename><replaceable>network_service</replaceable>.dnssd</filename></para>
  </refsynopsisdiv>

  <refsect1>
    <title>Description</title>

    <para>DNS-SD setup is performed by
    <citerefentry><refentrytitle>systemd-resolved</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
    </para>

    <para>The main network service file must have the extension <filename>.dnssd</filename>; other
    extensions are ignored.</para>

    <para>The <filename>.dnssd</filename> files are read from the files located in the system
    network directory <filename>/usr/lib/systemd/dnssd</filename>, the volatile runtime network
    directory <filename>/run/systemd/dnssd</filename> and the local administration network
    directory <filename>/etc/systemd/dnssd</filename>. All configuration files are collectively
    sorted and processed in lexical order, regardless of the directories in which they live.
    However, files with identical filenames replace each other. Files in <filename>/etc</filename>
    have the highest priority, files in <filename>/run</filename> take precedence over files with
    the same name in <filename>/usr/lib</filename>. This can be used to override a system-supplied
    configuration file with a local file if needed.</para>

    <para>Along with the network service file <filename>foo.dnssd</filename>, a "drop-in" directory
    <filename>foo.dnssd.d/</filename> may exist. All files with the suffix
    <literal>.conf</literal> from this directory will be parsed after the file itself is
    parsed. This is useful to alter or add configuration settings, without having to modify the main
    configuration file. Each drop-in file must have appropriate section headers.</para>

    <para>In addition to <filename>/etc/systemd/dnssd</filename>, drop-in <literal>.d</literal>
    directories can be placed in <filename>/usr/lib/systemd/dnssd</filename> or
    <filename>/run/systemd/dnssd</filename> directories. Drop-in files in
    <filename>/etc</filename> take precedence over those in <filename>/run</filename> which in turn
    take precedence over those in <filename>/usr/lib</filename>. Drop-in files under any of these
    directories take precedence over the main network service file wherever located. (Of course, since
    <filename>/run</filename> is temporary and <filename>/usr/lib</filename> is for vendors, it is
    unlikely drop-ins should be used in either of those places.)</para>
  </refsect1>

  <refsect1>
    <title>[Service] Section Options</title>

      <para>The network service file contains a <literal>[Service]</literal>
      section, which specifies a discoverable network service announced in a
      local network with Multicast DNS broadcasts.</para>

      <variablelist class='network-directives'>
        <varlistentry>
          <term><varname>Name=</varname></term>
          <listitem>
            <para>An instance name of the network service as defined in the section 4.1.1 of <ulink
            url="https://tools.ietf.org/html/rfc6763">RFC 6763</ulink>, e.g. <literal>webserver</literal>.</para>
            <para>The option supports simple specifier expansion. The following expansions are understood:</para>
            <table>
              <title>Specifiers available</title>
              <tgroup cols='3' align='left' colsep='1' rowsep='1'>
                <colspec colname="spec" />
                <colspec colname="mean" />
                <colspec colname="detail" />
                <thead>
                  <row>
                    <entry>Specifier</entry>
                    <entry>Meaning</entry>
                    <entry>Details</entry>
                  </row>
                </thead>
                <tbody>
                  <row>
                    <entry><literal>%m</literal></entry>
                    <entry>Machine ID</entry>
                    <entry>The machine ID of the running system, formatted as string. See <citerefentry><refentrytitle>machine-id</refentrytitle><manvolnum>5</manvolnum></citerefentry> for more information.</entry>
                  </row>
                  <row>
                    <entry><literal>%b</literal></entry>
                    <entry>Boot ID</entry>
                    <entry>The boot ID of the running system, formatted as string. See <citerefentry><refentrytitle>random</refentrytitle><manvolnum>4</manvolnum></citerefentry> for more information.</entry>
                  </row>
                  <row>
                    <entry><literal>%H</literal></entry>
                    <entry>Host name</entry>
                    <entry>The hostname of the running system.</entry>
                  </row>
                  <row>
                    <entry><literal>%v</literal></entry>
                    <entry>Kernel release</entry>
                    <entry>Identical to <command>uname -r</command> output.</entry>
                  </row>
                </tbody>
              </tgroup>
            </table>
          </listitem>
        </varlistentry>
        <varlistentry>
          <term><varname>Type=</varname></term>
          <listitem>
            <para>A type of the network service as defined in the section 4.1.2 of <ulink
            url="https://tools.ietf.org/html/rfc6763">RFC 6763</ulink>, e.g. <literal>_http._tcp</literal>.
            </para>
          </listitem>
        </varlistentry>
        <varlistentry>
          <term><varname>Port=</varname></term>
          <listitem>
            <para>An IP port number of the network service.</para>
          </listitem>
        </varlistentry>
        <varlistentry>
          <term><varname>Priority=</varname></term>
          <listitem>
            <para>A priority number set in SRV resource records corresponding to the network service.</para>
          </listitem>
        </varlistentry>
        <varlistentry>
          <term><varname>Weight=</varname></term>
          <listitem>
            <para>A weight number set in SRV resource records corresponding to the network service.</para>
          </listitem>
        </varlistentry>
        <varlistentry>
          <term><varname>TxtText=</varname></term>
          <listitem>
            <para>A whitespace-separated list of arbitrary key/value pairs
            conveying additional information about the named service in the corresponding TXT resource record,
            e.g. <literal>path=/portal/index.html</literal>. Keys and values can contain C-style escape
            sequences which get translated upon reading configuration files.
            </para>
            <para>This option together with <varname>TxtData=</varname> may be specified more than once, in which
            case multiple TXT resource records will be created for the service. If the empty string is assigned to
            this option, the list is reset and all prior assignments will have no effect.
            </para>
          </listitem>
        </varlistentry>
        <varlistentry>
          <term><varname>TxtData=</varname></term>
          <listitem>
            <para>A whitespace-separated list of arbitrary key/value pairs
            conveying additional information about the named service in the corresponding TXT resource record
            where values are base64-encoded string representing any binary data,
            e.g. <literal>data=YW55IGJpbmFyeSBkYXRhCg==</literal>. Keys can contain C-style escape
            sequences which get translated upon reading configuration files.
            </para>
            <para>This option together with <varname>TxtText=</varname> may be specified more than once, in which
            case multiple TXT resource records will be created for the service. If the empty string is assigned to
            this option, the list is reset and all prior assignments will have no effect.
            </para>
          </listitem>
        </varlistentry>
      </variablelist>

  </refsect1>

  <refsect1>
    <title>Examples</title>
    <example>
      <title>HTTP service</title>

      <programlisting># /etc/systemd/dnssd/http.dnssd
[Service]
Name=%H
Type=_http._tcp
Port=80
TxtText=path=/stats/index.html t=temperature_sensor</programlisting>

      <para>This makes the http server running on the host discoverable in the local network
      given MulticastDNS is enabled on the network interface.</para>

      <para>Now the utility <literal>systemd-resolve</literal> should be able to resolve the
      service to the host's name:</para>

      <programlisting>$ systemd-resolve  --service meteo._http._tcp.local
meteo._http._tcp.local: meteo.local:80 [priority=0, weight=0]
                        169.254.208.106%senp0s21f0u2u4
                        fe80::213:3bff:fe49:8aa%senp0s21f0u2u4
                        path=/stats/index.html
                        t=temperature_sensor
                        (meteo/_http._tcp/local)

-- Information acquired via protocol mDNS/IPv6 in 4.0ms.
-- Data is authenticated: yes</programlisting>

      <para><literal>Avahi</literal> running on a different host in the same local network should see the service as well:</para>

      <programlisting>$ avahi-browse -a -r
+ enp3s0 IPv6 meteo                                         Web Site             local
+ enp3s0 IPv4 meteo                                         Web Site             local
= enp3s0 IPv6 meteo                                         Web Site             local
   hostname = [meteo.local]
   address = [fe80::213:3bff:fe49:8aa]
   port = [80]
   txt = ["path=/stats/index.html" "t=temperature_sensor"]
= enp3s0 IPv4 meteo                                         Web Site             local
   hostname = [meteo.local]
   address = [169.254.208.106]
   port = [80]
   txt = ["path=/stats/index.html" "t=temperature_sensor"]</programlisting>

    </example>
  </refsect1>

  <refsect1>
    <title>See Also</title>
    <para>
      <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
      <citerefentry><refentrytitle>systemd-resolved.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>
    </para>
  </refsect1>

</refentry>
Commit	Line	Data
6e73d91e DR	1	<?xml version='1.0'?> <!--- Mode: nxml; nxml-child-indent: 2; indent-tabs-mode: nil --->
	2	<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
	3	"http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
	4
	5	<!--
	6	This file is part of systemd.
	7
	8	Copyright 2017 Dmitry Rozhkov
6e73d91e DR	9	-->
	10
	11	<refentry id="systemd.dnssd" conditional='ENABLE_RESOLVE'>
	12
	13	<refentryinfo>
	14	<title>systemd.dnssd</title>
	15	<productname>systemd</productname>
	16
	17	<authorgroup>
	18	<author>
	19	<contrib>Developer</contrib>
	20	<firstname>Dmitry</firstname>
	21	<surname>Rozhkov</surname>
	22	<email>dmitry.rozhkov@intel.com</email>
	23	</author>
	24	</authorgroup>
	25	</refentryinfo>
	26
	27	<refmeta>
	28	<refentrytitle>systemd.dnssd</refentrytitle>
	29	<manvolnum>5</manvolnum>
	30	</refmeta>
	31
	32	<refnamediv>
	33	<refname>systemd.dnssd</refname>
	34	<refpurpose>DNS-SD configuration</refpurpose>
	35	</refnamediv>
	36
	37	<refsynopsisdiv>
	38	<para><filename><replaceable>network_service</replaceable>.dnssd</filename></para>
	39	</refsynopsisdiv>
	40
	41	<refsect1>
	42	<title>Description</title>
	43
	44	<para>DNS-SD setup is performed by
	45	<citerefentry><refentrytitle>systemd-resolved</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
	46	</para>
	47
	48	<para>The main network service file must have the extension <filename>.dnssd</filename>; other
	49	extensions are ignored.</para>
	50
	51	<para>The <filename>.dnssd</filename> files are read from the files located in the system
	52	network directory <filename>/usr/lib/systemd/dnssd</filename>, the volatile runtime network
	53	directory <filename>/run/systemd/dnssd</filename> and the local administration network
	54	directory <filename>/etc/systemd/dnssd</filename>. All configuration files are collectively
	55	sorted and processed in lexical order, regardless of the directories in which they live.
	56	However, files with identical filenames replace each other. Files in <filename>/etc</filename>
	57	have the highest priority, files in <filename>/run</filename> take precedence over files with
	58	the same name in <filename>/usr/lib</filename>. This can be used to override a system-supplied
	59	configuration file with a local file if needed.</para>
	60
	61	<para>Along with the network service file <filename>foo.dnssd</filename>, a "drop-in" directory
	62	<filename>foo.dnssd.d/</filename> may exist. All files with the suffix
	63	<literal>.conf</literal> from this directory will be parsed after the file itself is
	64	parsed. This is useful to alter or add configuration settings, without having to modify the main
	65	configuration file. Each drop-in file must have appropriate section headers.</para>
	66
	67	<para>In addition to <filename>/etc/systemd/dnssd</filename>, drop-in <literal>.d</literal>
	68	directories can be placed in <filename>/usr/lib/systemd/dnssd</filename> or
	69	<filename>/run/systemd/dnssd</filename> directories. Drop-in files in
	70	<filename>/etc</filename> take precedence over those in <filename>/run</filename> which in turn
	71	take precedence over those in <filename>/usr/lib</filename>. Drop-in files under any of these
	72	directories take precedence over the main network service file wherever located. (Of course, since
73	<filename>/run</filename> is temporary and <filename>/usr/lib</filename> is for vendors, it is
74	unlikely drop-ins should be used in either of those places.)</para>
75	</refsect1>
76
77	<refsect1>
78	<title>[Service] Section Options</title>
79
80	<para>The network service file contains a <literal>[Service]</literal>
81	section, which specifies a discoverable network service announced in a
82	local network with Multicast DNS broadcasts.</para>
83
84	<variablelist class='network-directives'>
85	<varlistentry>
86	<term><varname>Name=</varname></term>
87	<listitem>
88	<para>An instance name of the network service as defined in the section 4.1.1 of <ulink
89	url="https://tools.ietf.org/html/rfc6763">RFC 6763</ulink>, e.g. <literal>webserver</literal>.</para>
90	<para>The option supports simple specifier expansion. The following expansions are understood:</para>
91	<table>
92	<title>Specifiers available</title>
93	<tgroup cols='3' align='left' colsep='1' rowsep='1'>
94	<colspec colname="spec" />
95	<colspec colname="mean" />
96	<colspec colname="detail" />
97	<thead>
98	<row>
99	<entry>Specifier</entry>
100	<entry>Meaning</entry>
101	<entry>Details</entry>
102	</row>
103	</thead>
104	<tbody>
105	<row>
106	<entry><literal>%m</literal></entry>
107	<entry>Machine ID</entry>
108	<entry>The machine ID of the running system, formatted as string. See <citerefentry><refentrytitle>machine-id</refentrytitle><manvolnum>5</manvolnum></citerefentry> for more information.</entry>
109	</row>
110	<row>
111	<entry><literal>%b</literal></entry>
112	<entry>Boot ID</entry>
113	<entry>The boot ID of the running system, formatted as string. See <citerefentry><refentrytitle>random</refentrytitle><manvolnum>4</manvolnum></citerefentry> for more information.</entry>
114	</row>
115	<row>
116	<entry><literal>%H</literal></entry>
117	<entry>Host name</entry>
118	<entry>The hostname of the running system.</entry>
119	</row>
120	<row>
121	<entry><literal>%v</literal></entry>
122	<entry>Kernel release</entry>
123	<entry>Identical to <command>uname -r</command> output.</entry>
124	</row>
125	</tbody>
126	</tgroup>
127	</table>
128	</listitem>
129	</varlistentry>
130	<varlistentry>
131	<term><varname>Type=</varname></term>
132	<listitem>
133	<para>A type of the network service as defined in the section 4.1.2 of <ulink
134	url="https://tools.ietf.org/html/rfc6763">RFC 6763</ulink>, e.g. <literal>_http._tcp</literal>.
135	</para>
136	</listitem>
137	</varlistentry>
138	<varlistentry>
139	<term><varname>Port=</varname></term>
140	<listitem>
141	<para>An IP port number of the network service.</para>
142	</listitem>
143	</varlistentry>
144	<varlistentry>
145	<term><varname>Priority=</varname></term>
146	<listitem>
147	<para>A priority number set in SRV resource records corresponding to the network service.</para>
148	</listitem>
149	</varlistentry>
150	<varlistentry>
151	<term><varname>Weight=</varname></term>
152	<listitem>
153	<para>A weight number set in SRV resource records corresponding to the network service.</para>
154	</listitem>
155	</varlistentry>
156	<varlistentry>
157	<term><varname>TxtText=</varname></term>
158	<listitem>
159	<para>A whitespace-separated list of arbitrary key/value pairs
160	conveying additional information about the named service in the corresponding TXT resource record,
161	e.g. <literal>path=/portal/index.html</literal>. Keys and values can contain C-style escape
162	sequences which get translated upon reading configuration files.
163	</para>
400f54fb DR	164	<para>This option together with <varname>TxtData=</varname> may be specified more than once, in which
	165	case multiple TXT resource records will be created for the service. If the empty string is assigned to
	166	this option, the list is reset and all prior assignments will have no effect.
	167	</para>
6e73d91e DR	168	</listitem>
	169	</varlistentry>
	170	<varlistentry>
	171	<term><varname>TxtData=</varname></term>
	172	<listitem>
	173	<para>A whitespace-separated list of arbitrary key/value pairs
	174	conveying additional information about the named service in the corresponding TXT resource record
	175	where values are base64-encoded string representing any binary data,
	176	e.g. <literal>data=YW55IGJpbmFyeSBkYXRhCg==</literal>. Keys can contain C-style escape
	177	sequences which get translated upon reading configuration files.
	178	</para>
400f54fb DR	179	<para>This option together with <varname>TxtText=</varname> may be specified more than once, in which
	180	case multiple TXT resource records will be created for the service. If the empty string is assigned to
	181	this option, the list is reset and all prior assignments will have no effect.
	182	</para>
6e73d91e DR	183	</listitem>
	184	</varlistentry>
	185	</variablelist>
	186
	187	</refsect1>
	188
	189	<refsect1>
	190	<title>Examples</title>
	191	<example>
	192	<title>HTTP service</title>
	193
	194	<programlisting># /etc/systemd/dnssd/http.dnssd
	195	[Service]
5526ac50	196	Name=%H
6e73d91e DR	197	Type=_http._tcp
	198	Port=80
	199	TxtText=path=/stats/index.html t=temperature_sensor</programlisting>
	200
	201	<para>This makes the http server running on the host discoverable in the local network
	202	given MulticastDNS is enabled on the network interface.</para>
	203
	204	<para>Now the utility <literal>systemd-resolve</literal> should be able to resolve the
	205	service to the host's name:</para>
	206
	207	<programlisting>$ systemd-resolve --service meteo._http._tcp.local
	208	meteo._http._tcp.local: meteo.local:80 [priority=0, weight=0]
	209	169.254.208.106%senp0s21f0u2u4
	210	fe80::213:3bff:fe49:8aa%senp0s21f0u2u4
	211	path=/stats/index.html
	212	t=temperature_sensor
	213	(meteo/_http._tcp/local)
	214
	215	-- Information acquired via protocol mDNS/IPv6 in 4.0ms.
	216	-- Data is authenticated: yes</programlisting>
	217
	218	<para><literal>Avahi</literal> running on a different host in the same local network should see the service as well:</para>
	219
	220	<programlisting>$ avahi-browse -a -r
	221	+ enp3s0 IPv6 meteo Web Site local
	222	+ enp3s0 IPv4 meteo Web Site local
	223	= enp3s0 IPv6 meteo Web Site local
	224	hostname = [meteo.local]
	225	address = [fe80::213:3bff:fe49:8aa]
	226	port = [80]
	227	txt = ["path=/stats/index.html" "t=temperature_sensor"]
	228	= enp3s0 IPv4 meteo Web Site local
	229	hostname = [meteo.local]
	230	address = [169.254.208.106]
	231	port = [80]
	232	txt = ["path=/stats/index.html" "t=temperature_sensor"]</programlisting>
	233
	234	</example>
	235	</refsect1>
	236
	237	<refsect1>
	238	<title>See Also</title>
	239	<para>
	240	<citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
	241	<citerefentry><refentrytitle>systemd-resolved.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>
	242	</para>
	243	</refsect1>
	244
	245	</refentry>