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

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<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
  "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">

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  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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<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
	9
	10	systemd is free software; you can redistribute it and/or modify it
	11	under the terms of the GNU Lesser General Public License as published by
	12	the Free Software Foundation; either version 2.1 of the License, or
	13	(at your option) any later version.
	14
	15	systemd is distributed in the hope that it will be useful, but
	16	WITHOUT ANY WARRANTY; without even the implied warranty of
	17	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
	18	Lesser General Public License for more details.
	19
	20	You should have received a copy of the GNU Lesser General Public License
	21	along with systemd; If not, see <http://www.gnu.org/licenses/>.
	22	-->
	23
	24	<refentry id="systemd.dnssd" conditional='ENABLE_RESOLVE'>
	25
	26	<refentryinfo>
	27	<title>systemd.dnssd</title>
	28	<productname>systemd</productname>
	29
	30	<authorgroup>
	31	<author>
	32	<contrib>Developer</contrib>
	33	<firstname>Dmitry</firstname>
	34	<surname>Rozhkov</surname>
	35	<email>dmitry.rozhkov@intel.com</email>
	36	</author>
	37	</authorgroup>
	38	</refentryinfo>
	39
	40	<refmeta>
	41	<refentrytitle>systemd.dnssd</refentrytitle>
	42	<manvolnum>5</manvolnum>
	43	</refmeta>
	44
	45	<refnamediv>
	46	<refname>systemd.dnssd</refname>
	47	<refpurpose>DNS-SD configuration</refpurpose>
	48	</refnamediv>
	49
	50	<refsynopsisdiv>
	51	<para><filename><replaceable>network_service</replaceable>.dnssd</filename></para>
	52	</refsynopsisdiv>
	53
	54	<refsect1>
	55	<title>Description</title>
	56
	57	<para>DNS-SD setup is performed by
	58	<citerefentry><refentrytitle>systemd-resolved</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
	59	</para>
	60
	61	<para>The main network service file must have the extension <filename>.dnssd</filename>; other
	62	extensions are ignored.</para>
	63
	64	<para>The <filename>.dnssd</filename> files are read from the files located in the system
65	network directory <filename>/usr/lib/systemd/dnssd</filename>, the volatile runtime network
66	directory <filename>/run/systemd/dnssd</filename> and the local administration network
67	directory <filename>/etc/systemd/dnssd</filename>. All configuration files are collectively
68	sorted and processed in lexical order, regardless of the directories in which they live.
69	However, files with identical filenames replace each other. Files in <filename>/etc</filename>
70	have the highest priority, files in <filename>/run</filename> take precedence over files with
71	the same name in <filename>/usr/lib</filename>. This can be used to override a system-supplied
72	configuration file with a local file if needed.</para>
73
74	<para>Along with the network service file <filename>foo.dnssd</filename>, a "drop-in" directory
75	<filename>foo.dnssd.d/</filename> may exist. All files with the suffix
76	<literal>.conf</literal> from this directory will be parsed after the file itself is
77	parsed. This is useful to alter or add configuration settings, without having to modify the main
78	configuration file. Each drop-in file must have appropriate section headers.</para>
79
80	<para>In addition to <filename>/etc/systemd/dnssd</filename>, drop-in <literal>.d</literal>
81	directories can be placed in <filename>/usr/lib/systemd/dnssd</filename> or
82	<filename>/run/systemd/dnssd</filename> directories. Drop-in files in
83	<filename>/etc</filename> take precedence over those in <filename>/run</filename> which in turn
84	take precedence over those in <filename>/usr/lib</filename>. Drop-in files under any of these
85	directories take precedence over the main network service file wherever located. (Of course, since
86	<filename>/run</filename> is temporary and <filename>/usr/lib</filename> is for vendors, it is
87	unlikely drop-ins should be used in either of those places.)</para>
88	</refsect1>
89
90	<refsect1>
91	<title>[Service] Section Options</title>
92
93	<para>The network service file contains a <literal>[Service]</literal>
94	section, which specifies a discoverable network service announced in a
95	local network with Multicast DNS broadcasts.</para>
96
97	<variablelist class='network-directives'>
98	<varlistentry>
99	<term><varname>Name=</varname></term>
100	<listitem>
101	<para>An instance name of the network service as defined in the section 4.1.1 of <ulink
102	url="https://tools.ietf.org/html/rfc6763">RFC 6763</ulink>, e.g. <literal>webserver</literal>.</para>
103	<para>The option supports simple specifier expansion. The following expansions are understood:</para>
104	<table>
105	<title>Specifiers available</title>
106	<tgroup cols='3' align='left' colsep='1' rowsep='1'>
107	<colspec colname="spec" />
108	<colspec colname="mean" />
109	<colspec colname="detail" />
110	<thead>
111	<row>
112	<entry>Specifier</entry>
113	<entry>Meaning</entry>
114	<entry>Details</entry>
115	</row>
116	</thead>
117	<tbody>
118	<row>
119	<entry><literal>%m</literal></entry>
120	<entry>Machine ID</entry>
121	<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>
122	</row>
123	<row>
124	<entry><literal>%b</literal></entry>
125	<entry>Boot ID</entry>
126	<entry>The boot ID of the running system, formatted as string. See <citerefentry><refentrytitle>random</refentrytitle><manvolnum>4</manvolnum></citerefentry> for more information.</entry>
127	</row>
128	<row>
129	<entry><literal>%H</literal></entry>
130	<entry>Host name</entry>
131	<entry>The hostname of the running system.</entry>
132	</row>
133	<row>
134	<entry><literal>%v</literal></entry>
135	<entry>Kernel release</entry>
136	<entry>Identical to <command>uname -r</command> output.</entry>
137	</row>
138	</tbody>
139	</tgroup>
140	</table>
141	</listitem>
142	</varlistentry>
143	<varlistentry>
144	<term><varname>Type=</varname></term>
145	<listitem>
146	<para>A type of the network service as defined in the section 4.1.2 of <ulink
147	url="https://tools.ietf.org/html/rfc6763">RFC 6763</ulink>, e.g. <literal>_http._tcp</literal>.
148	</para>
149	</listitem>
150	</varlistentry>
151	<varlistentry>
152	<term><varname>Port=</varname></term>
153	<listitem>
154	<para>An IP port number of the network service.</para>
155	</listitem>
156	</varlistentry>
157	<varlistentry>
158	<term><varname>Priority=</varname></term>
159	<listitem>
160	<para>A priority number set in SRV resource records corresponding to the network service.</para>
161	</listitem>
162	</varlistentry>
163	<varlistentry>
164	<term><varname>Weight=</varname></term>
165	<listitem>
166	<para>A weight number set in SRV resource records corresponding to the network service.</para>
167	</listitem>
168	</varlistentry>
169	<varlistentry>
170	<term><varname>TxtText=</varname></term>
171	<listitem>
172	<para>A whitespace-separated list of arbitrary key/value pairs
173	conveying additional information about the named service in the corresponding TXT resource record,
174	e.g. <literal>path=/portal/index.html</literal>. Keys and values can contain C-style escape
175	sequences which get translated upon reading configuration files.
176	</para>
400f54fb DR	177	<para>This option together with <varname>TxtData=</varname> may be specified more than once, in which
	178	case multiple TXT resource records will be created for the service. If the empty string is assigned to
	179	this option, the list is reset and all prior assignments will have no effect.
	180	</para>
6e73d91e DR	181	</listitem>
	182	</varlistentry>
	183	<varlistentry>
	184	<term><varname>TxtData=</varname></term>
	185	<listitem>
	186	<para>A whitespace-separated list of arbitrary key/value pairs
	187	conveying additional information about the named service in the corresponding TXT resource record
	188	where values are base64-encoded string representing any binary data,
	189	e.g. <literal>data=YW55IGJpbmFyeSBkYXRhCg==</literal>. Keys can contain C-style escape
	190	sequences which get translated upon reading configuration files.
	191	</para>
400f54fb DR	192	<para>This option together with <varname>TxtText=</varname> may be specified more than once, in which
	193	case multiple TXT resource records will be created for the service. If the empty string is assigned to
	194	this option, the list is reset and all prior assignments will have no effect.
	195	</para>
6e73d91e DR	196	</listitem>
	197	</varlistentry>
	198	</variablelist>
	199
	200	</refsect1>
	201
	202	<refsect1>
	203	<title>Examples</title>
	204	<example>
	205	<title>HTTP service</title>
	206
	207	<programlisting># /etc/systemd/dnssd/http.dnssd
	208	[Service]
5526ac50	209	Name=%H
6e73d91e DR	210	Type=_http._tcp
	211	Port=80
	212	TxtText=path=/stats/index.html t=temperature_sensor</programlisting>
	213
	214	<para>This makes the http server running on the host discoverable in the local network
	215	given MulticastDNS is enabled on the network interface.</para>
	216
	217	<para>Now the utility <literal>systemd-resolve</literal> should be able to resolve the
	218	service to the host's name:</para>
	219
	220	<programlisting>$ systemd-resolve --service meteo._http._tcp.local
	221	meteo._http._tcp.local: meteo.local:80 [priority=0, weight=0]
	222	169.254.208.106%senp0s21f0u2u4
	223	fe80::213:3bff:fe49:8aa%senp0s21f0u2u4
	224	path=/stats/index.html
	225	t=temperature_sensor
	226	(meteo/_http._tcp/local)
	227
	228	-- Information acquired via protocol mDNS/IPv6 in 4.0ms.
	229	-- Data is authenticated: yes</programlisting>
	230
	231	<para><literal>Avahi</literal> running on a different host in the same local network should see the service as well:</para>
	232
	233	<programlisting>$ avahi-browse -a -r
	234	+ enp3s0 IPv6 meteo Web Site local
	235	+ enp3s0 IPv4 meteo Web Site local
	236	= enp3s0 IPv6 meteo Web Site local
	237	hostname = [meteo.local]
	238	address = [fe80::213:3bff:fe49:8aa]
	239	port = [80]
	240	txt = ["path=/stats/index.html" "t=temperature_sensor"]
	241	= enp3s0 IPv4 meteo Web Site local
	242	hostname = [meteo.local]
	243	address = [169.254.208.106]
	244	port = [80]
	245	txt = ["path=/stats/index.html" "t=temperature_sensor"]</programlisting>
	246
	247	</example>
	248	</refsect1>
	249
	250	<refsect1>
	251	<title>See Also</title>
	252	<para>
	253	<citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
	254	<citerefentry><refentrytitle>systemd-resolved.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>
	255	</para>
	256	</refsect1>
	257
	258	</refentry>