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+<?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
+
+ systemd is free software; you can redistribute it and/or modify it
+ under the terms of the GNU Lesser General Public License as published by
+ the Free Software Foundation; either version 2.1 of the License, or
+ (at your option) any later version.
+
+ systemd is distributed in the hope that it will be useful, but
+ WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ Lesser General Public License for more details.
+
+ You should have received a copy of the GNU Lesser General Public License
+ along with systemd; If not, see <http://www.gnu.org/licenses/>.
+-->
+
+<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>
+ </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>
+ </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>
projects / platform / upstream / systemd.git / commitdiff