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diff --git a/man/org.freedesktop.hostname1.xml b/man/org.freedesktop.hostname1.xml new file mode 100644 index 0000000..f8e199c --- /dev/null +++ b/man/org.freedesktop.hostname1.xml @@ -0,0 +1,368 @@ +<?xml version="1.0"?> +<!--*-nxml-*--> +<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN" + "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd" [ +<!ENTITY % entities SYSTEM "custom-entities.ent" > +%entities; +]> +<!-- SPDX-License-Identifier: LGPL-2.1-or-later --> + +<refentry id="org.freedesktop.hostname1" conditional='ENABLE_HOSTNAMED' + xmlns:xi="http://www.w3.org/2001/XInclude"> + <refentryinfo> + <title>org.freedesktop.hostname1</title> + <productname>systemd</productname> + </refentryinfo> + + <refmeta> + <refentrytitle>org.freedesktop.hostname1</refentrytitle> + <manvolnum>5</manvolnum> + </refmeta> + + <refnamediv> + <refname>org.freedesktop.hostname1</refname> + <refpurpose>The D-Bus interface of systemd-hostnamed</refpurpose> + </refnamediv> + + <refsect1> + <title>Introduction</title> + + <para> + <citerefentry><refentrytitle>systemd-hostnamed.service</refentrytitle><manvolnum>8</manvolnum></citerefentry> + is a system service that can be used to control the hostname and related machine metadata from user + programs. This page describes the hostname semantics and the D-Bus interface.</para> + </refsect1> + + <refsect1> + <title>The D-Bus API</title> + + <para>The service exposes the following interfaces on the bus:</para> + + <programlisting executable="systemd-hostnamed" node="/org/freedesktop/hostname1" interface="org.freedesktop.hostname1"> +node /org/freedesktop/hostname1 { + interface org.freedesktop.hostname1 { + methods: + SetHostname(in s hostname, + in b interactive); + SetStaticHostname(in s hostname, + in b interactive); + SetPrettyHostname(in s hostname, + in b interactive); + SetIconName(in s icon, + in b interactive); + SetChassis(in s chassis, + in b interactive); + SetDeployment(in s deployment, + in b interactive); + SetLocation(in s location, + in b interactive); + GetProductUUID(in b interactive, + out ay uuid); + properties: + readonly s Hostname = '...'; + readonly s StaticHostname = '...'; + readonly s PrettyHostname = '...'; + readonly s IconName = '...'; + readonly s Chassis = '...'; + readonly s Deployment = '...'; + readonly s Location = '...'; + @org.freedesktop.DBus.Property.EmitsChangedSignal("const") + readonly s KernelName = '...'; + @org.freedesktop.DBus.Property.EmitsChangedSignal("const") + readonly s KernelRelease = '...'; + @org.freedesktop.DBus.Property.EmitsChangedSignal("const") + readonly s KernelVersion = '...'; + @org.freedesktop.DBus.Property.EmitsChangedSignal("const") + readonly s OperatingSystemPrettyName = '...'; + @org.freedesktop.DBus.Property.EmitsChangedSignal("const") + readonly s OperatingSystemCPEName = '...'; + @org.freedesktop.DBus.Property.EmitsChangedSignal("const") + readonly s HomeURL = '...'; + }; + interface org.freedesktop.DBus.Peer { ... }; + interface org.freedesktop.DBus.Introspectable { ... }; + interface org.freedesktop.DBus.Properties { ... }; +}; + </programlisting> + + <!--Autogenerated cross-references for systemd.directives, do not edit--> + + <variablelist class="dbus-interface" generated="True" extra-ref="org.freedesktop.hostname1"/> + + <variablelist class="dbus-interface" generated="True" extra-ref="org.freedesktop.hostname1"/> + + <variablelist class="dbus-method" generated="True" extra-ref="SetHostname()"/> + + <variablelist class="dbus-method" generated="True" extra-ref="SetStaticHostname()"/> + + <variablelist class="dbus-method" generated="True" extra-ref="SetPrettyHostname()"/> + + <variablelist class="dbus-method" generated="True" extra-ref="SetIconName()"/> + + <variablelist class="dbus-method" generated="True" extra-ref="SetChassis()"/> + + <variablelist class="dbus-method" generated="True" extra-ref="SetDeployment()"/> + + <variablelist class="dbus-method" generated="True" extra-ref="SetLocation()"/> + + <variablelist class="dbus-method" generated="True" extra-ref="GetProductUUID()"/> + + <variablelist class="dbus-property" generated="True" extra-ref="Hostname"/> + + <variablelist class="dbus-property" generated="True" extra-ref="StaticHostname"/> + + <variablelist class="dbus-property" generated="True" extra-ref="PrettyHostname"/> + + <variablelist class="dbus-property" generated="True" extra-ref="IconName"/> + + <variablelist class="dbus-property" generated="True" extra-ref="Chassis"/> + + <variablelist class="dbus-property" generated="True" extra-ref="Deployment"/> + + <variablelist class="dbus-property" generated="True" extra-ref="Location"/> + + <variablelist class="dbus-property" generated="True" extra-ref="KernelName"/> + + <variablelist class="dbus-property" generated="True" extra-ref="KernelRelease"/> + + <variablelist class="dbus-property" generated="True" extra-ref="KernelVersion"/> + + <variablelist class="dbus-property" generated="True" extra-ref="OperatingSystemPrettyName"/> + + <variablelist class="dbus-property" generated="True" extra-ref="OperatingSystemCPEName"/> + + <variablelist class="dbus-property" generated="True" extra-ref="HomeURL"/> + + <!--End of Autogenerated section--> + + <para>Whenever the hostname or other metadata is changed via the daemon, + <function>PropertyChanged</function> signals are sent out to subscribed clients. Changing a hostname + using this interface is authenticated via + <ulink url="https://www.freedesktop.org/software/polkit/docs/latest/">polkit</ulink>.</para> + </refsect1> + + <refsect1> + <title>Semantics</title> + + <para>The <emphasis>static (configured) hostname</emphasis> is the one configured in + <filename>/etc/hostname</filename>. It is chosen by the local user. It is not always in sync with the + current hostname as returned by the + <citerefentry project="man-pages"><refentrytitle>gethostname</refentrytitle><manvolnum>3</manvolnum></citerefentry> + system call. If no hostname is configured this property will be the empty string. Setting this property + to the empty string will remove <filename>/etc/hostname</filename>. This property should be an + internet-style hostname, 7-bit lowercase ASCII, no special chars/spaces.</para> + + <para>The <emphasis>transient (dynamic) hostname</emphasis> is the one configured via the kernel's + <citerefentry project="man-pages"><refentrytitle>sethostname</refentrytitle><manvolnum>3</manvolnum></citerefentry>. + It can be different from the static hostname if DHCP or mDNS have been configured to change the name + based on network information. <!-- FIXME: it's not DHCP that configures this... --> + This property is never empty. If no hostname is set this will default to + <literal>&FALLBACK_HOSTNAME;</literal> (configurable at compilation time). Setting this property to the + empty string will reset the dynamic hostname to the static hostname. If no static hostname is + configured the dynamic hostname will be reset to <literal>&FALLBACK_HOSTNAME;</literal>. This property + should be an internet-style hostname, 7-bit lowercase ASCII, no special chars/spaces.</para> + + <para>The <emphasis>pretty hostname</emphasis> is a free-form UTF-8 hostname for presentation to the + user. User interfaces should ensure that the pretty hostname and the static hostname stay in sync. + I.e. when the former is <literal>Lennart’s Computer</literal> the latter should be + <literal>lennarts-computer</literal>. If no pretty hostname is set this setting will be the empty + string. Applications should then find a suitable fallback, such as the dynamic hostname.</para> + + <para>The <emphasis>icon name</emphasis> is a name following the XDG icon naming spec. If not set, + information such as the chassis type (see below) is used to find a suitable fallback icon name + (i.e. <literal>computer-laptop</literal> vs. <literal>computer-desktop</literal> is picked based on the + chassis information). If no such data is available, the empty string is returned. In that case an application + should fall back to a replacement icon, for example <literal>computer</literal>. If this property is set + to the empty string, the automatic fallback name selection is enabled again.</para> + + <para>The <emphasis>chassis type</emphasis> should be one of the currently defined chassis types: + <literal>desktop</literal>, <literal>laptop</literal>, <literal>server</literal>, + <literal>tablet</literal>, <literal>handset</literal>, as well as the special chassis types + <literal>vm</literal> and <literal>container</literal> for virtualized systems. Note that in most cases + the chassis type will be determined automatically from DMI/SMBIOS/ACPI firmware information. Writing to + this setting is hence useful only to override misdetected chassis types, or to configure the chassis type if + it could not be auto-detected. Set this property to the empty string to reenable the automatic detection of + the chassis type from firmware information.</para> + + <para>Note that <filename>systemd-hostnamed</filename> starts only on request and terminates after a + short idle period. This effectively means that <function>PropertyChanged</function> messages are not sent + out for changes made directly on the files (as in: administrator edits the files with vi). This is + the intended behavior: manual configuration changes should require manual reloading.</para> + + <para>The transient (dynamic) hostname maps directly to the kernel hostname. This hostname should be + assumed to be highly dynamic, and hence should be watched directly, without depending on + <function>PropertyChanged</function> messages from <filename>systemd-hostnamed</filename>. To accomplish + this, open <filename>/proc/sys/kernel/hostname</filename> and + <citerefentry project="man-pages"><refentrytitle>poll</refentrytitle><manvolnum>3</manvolnum></citerefentry> + for <constant>SIGHUP</constant> which is triggered by the kernel every time the hostname changes. Again: + this is special for the transient (dynamic) hostname, and does not apply to the configured (fixed) + hostname.</para> + + <para>Applications may read the hostname data directly if hostname change notifications + are not necessary. Use + <citerefentry project="man-pages"><refentrytitle>gethostname</refentrytitle><manvolnum>3</manvolnum></citerefentry>, + <filename>/etc/hostname</filename> (possibly with per-distribution fallbacks), and + <citerefentry><refentrytitle>machine-info</refentrytitle><manvolnum>3</manvolnum></citerefentry> + for that. For more information on these files and syscalls see the respective man pages.</para> + + <refsect2> + <title>Methods and Properties</title> + + <para><function>SetHostname()</function> sets the transient (dynamic) hostname which is exposed by the + <varname>Hostname</varname> property. If empty, the transient hostname is set to the static hostname. + </para> + + <para><function>SetStaticHostname()</function> sets the static hostname which is exposed by the + <varname>StaticHostname</varname> property. If empty, the built-in default of + <literal>&FALLBACK_HOSTNAME;</literal> is used.</para> + + <para><function>SetPrettyHostname()</function> sets the pretty hostname which is exposed by the + <varname>PrettyHostname</varname> property.</para> + + <para><function>SetIconName()</function>, <function>SetChassis()</function>, + <function>SetDeployment()</function>, and <function>SetLocation()</function> set the properties + <varname>IconName</varname> (the name of the icon representing for the machine), + <varname>Chassis</varname> (the machine form factor), <varname>Deployment</varname> (the system + deployment environment), and <varname>Location</varname> (physical system location), respectively. + </para> + + <para><varname>PrettyHostname</varname>, <varname>IconName</varname>, <varname>Chassis</varname>, + <varname>Deployment</varname>, and <varname>Location</varname> are stored in + <filename>/etc/machine-info</filename>. See + <citerefentry><refentrytitle>machine-info</refentrytitle><manvolnum>5</manvolnum></citerefentry> for + the semantics of those settings.</para> + + <para><function>GetProductUUID()</function> returns the "product uuid" as exposed by the kernel based + on DMI information in <filename>/sys/class/dmi/id/product_uuid</filename>. Reading the file directly + requires root privileges, and this method allows access to unprivileged clients through the polkit + framework.</para> + + <para><varname>KernelName</varname>, <varname>KernelRelease</varname>, and + <varname>KernelVersion</varname> expose the kernel name (e.g. <literal>Linux</literal>), release + (e.g. <literal>5.0.0-11</literal>), and version (i.e. the build number, e.g. <literal>#11</literal>) as + reported by + <citerefentry project="man-pages"><refentrytitle>uname</refentrytitle><manvolnum>2</manvolnum></citerefentry>. + <varname>OperatingSystemPrettyName</varname>, <varname>OperatingSystemCPEName</varname>, and + <varname>HomeURL</varname> expose the <varname>PRETTY_NAME=</varname>, <varname>CPE_NAME=</varname> and + <varname>HOME_URL=</varname> fields from + <citerefentry><refentrytitle>os-release</refentrytitle><manvolnum>5</manvolnum></citerefentry>. The + purpose of those properties is to allow remote clients to access this information over D-Bus. Local + clients can access the information directly.</para> + </refsect2> + + <refsect2> + <title>Security</title> + + <para>The <varname>interactive</varname> boolean parameters can be used to control whether polkit + should interactively ask the user for authentication credentials if required.</para> + + <para>The polkit action for <function>SetHostname()</function> is + <interfacename>org.freedesktop.hostname1.set-hostname</interfacename>. For + <function>SetStaticHostname()</function> and <function>SetPrettyHostname()</function> it is + <interfacename>org.freedesktop.hostname1.set-static-hostname</interfacename>. For + <function>SetIconName()</function>, <function>SetChassis()</function>, <function>SetDeployment()</function> + and <function>SetLocation()</function> it is + <interfacename>org.freedesktop.hostname1.set-machine-info</interfacename>.</para> + </refsect2> + </refsect1> + + <refsect1> + <title>Recommendations</title> + + <para>Here are three examples that show how the pretty hostname and the icon name should be used: + <itemizedlist> + <listitem><para>When registering DNS-SD services: use the pretty hostname in the service name, and pass + the icon name in the TXT data, if there is an icon name. Browsing clients can then show the server icon + on each service. This is especially useful for WebDAV applications or UPnP media sharing. + </para></listitem> + + <listitem><para>Set the bluetooth name to the pretty hostname.</para></listitem> + + <listitem><para>When your file browser has a "Computer" icon, replace the name with the pretty hostname + if set, and the icon with the icon name, if it is set.</para></listitem> + </itemizedlist></para> + + <para>To properly handle name lookups with changing local hostnames without having to edit + <filename>/etc/hosts</filename>, we recommend using <filename>systemd-hostnamed</filename> in combination + with <citerefentry><refentrytitle>nss-myhostname</refentrytitle><manvolnum>3</manvolnum></citerefentry>. + </para> + + <para>A client that wants to change the local hostname for DHCP/mDNS should invoke + <code>SetHostname("newname", false)</code> as soon as the name is available and afterwards reset it via + <code>SetHostname("")</code>.</para> + + <para>Here are some recommendations to follow when generating a static (internet) hostname from a pretty + name: + <itemizedlist> + <listitem><para>Generate a single DNS label only, not an FQDN. That means no dots allowed. Strip them, + or replace them with <literal>-</literal>.</para></listitem> + + <listitem><para>It's probably safer to not use any non-ASCII chars, even if DNS allows this in some way + these days. In fact, restrict your charset to <literal>a-zA-Z0-9</literal> and <literal>-</literal>. + Strip other chars, or try to replace them in some smart way with chars from this set, for example + <literal>ä</literal> → <literal>ae</literal>, and use <literal>-</literal> as the replacement for all + punctuation characters and whitespace.</para></listitem> + + <listitem><para>Try to avoid creating repeated <literal>-</literal>, as well as <literal>-</literal> as + the first or last char.</para></listitem> + + <listitem><para>Limit the hostname to 63 chars, which is the length of a DNS label.</para></listitem> + + <listitem><para>If after stripping special chars the empty string is the result, you can pass this + as-is to <filename>systemd-hostnamed</filename> in which case it will automatically use + <literal>&FALLBACK_HOSTNAME;</literal>.</para></listitem> + + <listitem><para>Uppercase charaacters should be replaced with their lowercase equivalents. + </para></listitem> + </itemizedlist></para> + + <para>Note that while <filename>systemd-hostnamed</filename> applies some checks to the hostname you pass + they are much looser than the recommendations above. For example, <filename>systemd-hostnamed</filename> + will also accept <literal>_</literal> in the hostname, but we recommend not using this to avoid clashes + with DNS-SD service types. Also <filename>systemd-hostnamed</filename> allows longer hostnames, but + because of the DNS label limitations, we recommend not making use of this.</para> + + <para>Here are a couple of example conversions: + <itemizedlist> + <listitem><para><literal>Lennart's PC</literal> → <literal>lennarts-pc</literal></para></listitem> + <listitem><para><literal>Müllers Computer</literal> → <literal>muellers-computer</literal></para></listitem> + <listitem><para><literal>Voran!</literal> → <literal>voran</literal></para></listitem> + <listitem><para><literal>Es war einmal ein Männlein</literal> → <literal>es-war-einmal-ein-maennlein</literal></para></listitem> + <listitem><para><literal>Jawoll. Ist doch wahr!</literal> → <literal>jawoll-ist-doch-wahr</literal></para></listitem> + <listitem><para><literal>レナート</literal> → <literal>localhost</literal></para></listitem> + <listitem><para><literal>...zack!!! zack!...</literal> → <literal>zack-zack</literal></para></listitem> + </itemizedlist></para> + + <para>Of course, an already valid internet hostname label you enter and pass through this + conversion should stay unmodified, so that users have direct control of it, if they want — by simply + ignoring the fact that the pretty hostname is pretty and just edit it as if it was the normal internet + name.</para> + </refsect1> + + <refsect1> + <title>Versioning</title> + + <para>These D-Bus interfaces follow <ulink url="http://0pointer.de/blog/projects/versioning-dbus.html"> + the usual interface versioning guidelines</ulink>.</para> + </refsect1> + + <refsect1> + <title>Examples</title> + + <example> + <title>Introspect <interfacename>org.freedesktop.hostname1</interfacename> on the bus</title> + + <programlisting>$ gdbus introspect --system \ + --dest org.freedesktop.hostname1 \ + --object-path /org/freedesktop/hostname1 + </programlisting> + </example> + </refsect1> + + <refsect1> + <title>See also</title> + + <para>David Zeuthen's original Fedora + <ulink url="https://fedoraproject.org/wiki/Features/BetterHostname">Feature page about xdg-hostname</ulink></para> + </refsect1> +</refentry> |