| <?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" > |
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| ]> |
| <!-- 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); |
| Describe(out s json); |
| properties: |
| readonly s Hostname = '...'; |
| readonly s StaticHostname = '...'; |
| readonly s PrettyHostname = '...'; |
| @org.freedesktop.DBus.Property.EmitsChangedSignal("const") |
| readonly s DefaultHostname = '...'; |
| readonly s HostnameSource = '...'; |
| 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 = '...'; |
| @org.freedesktop.DBus.Property.EmitsChangedSignal("const") |
| readonly s HardwareVendor = '...'; |
| @org.freedesktop.DBus.Property.EmitsChangedSignal("const") |
| readonly s HardwareModel = '...'; |
| }; |
| interface org.freedesktop.DBus.Peer { ... }; |
| interface org.freedesktop.DBus.Introspectable { ... }; |
| interface org.freedesktop.DBus.Properties { ... }; |
| }; |
| </programlisting> |
| |
| <!--property HardwareVendor is not documented!--> |
| |
| <!--property HardwareModel is not documented!--> |
| |
| <!--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-method" generated="True" extra-ref="Describe()"/> |
| |
| <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="DefaultHostname"/> |
| |
| <variablelist class="dbus-property" generated="True" extra-ref="HostnameSource"/> |
| |
| <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"/> |
| |
| <variablelist class="dbus-property" generated="True" extra-ref="HardwareVendor"/> |
| |
| <variablelist class="dbus-property" generated="True" extra-ref="HardwareModel"/> |
| |
| <!--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 <varname>StaticHostname</varname> property exposes the "static" hostname configured in |
| <filename>/etc/hostname</filename>. 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 static hostname is configured this property will be the empty string.</para> |
| |
| <para>When <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry> or |
| <citerefentry><refentrytitle>systemd-hostnamed.service</refentrytitle><manvolnum>8</manvolnum></citerefentry> |
| set the hostname, this static hostname <emphasis>has the highest priority</emphasis>.</para> |
| |
| <para>The <varname>Hostname</varname> property exposes the actual hostname configured in the kernel via |
| <citerefentry project="man-pages"><refentrytitle>sethostname</refentrytitle><manvolnum>3</manvolnum></citerefentry>. |
| It can be different from the static hostname. This property is never empty.</para> |
| |
| <para>The <varname>PrettyHostname</varname> property exposes the <emphasis>pretty hostname</emphasis> |
| which 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. E.g. 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 <varname>DefaultHostname</varname> property exposes the default hostname (configured through |
| <citerefentry><refentrytitle>os-release</refentrytitle><manvolnum>5</manvolnum></citerefentry>, or a |
| fallback set at compilation time).</para> |
| |
| <para>The <varname>HostnameSource</varname> property exposes the origin of the currently configured |
| hostname. One of <literal>static</literal> (set from <filename>/etc/hostname</filename>), |
| <literal>transient</literal> (a non-permanent hostname from an external source), |
| <literal>default</literal> (the value from <filename>os-release</filename> or the compiled-in |
| fallback).</para> |
| |
| <para>The <varname>IconName</varname> property exposes the <emphasis>icon name</emphasis> 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 <varname>Chassis</varname> property exposes a <emphasis>chassis type</emphasis>, 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 exposed by the <varname>Hostname</varname> property 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> |
| |
| <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> |
| <title>Methods</title> |
| |
| <para><function>SetHostname()</function> sets the transient (dynamic) hostname, which is used if no |
| static hostname is set. This value must be an internet-style hostname, 7-bit lowercase ASCII, no |
| special chars/spaces. An empty string will unset the transient hostname.</para> |
| |
| <para><function>SetStaticHostname()</function> sets the static hostname which is exposed by the |
| <varname>StaticHostname</varname> property. When called with an empty argument, the static |
| configuration in <filename>/etc/hostname</filename> is removed. Since the static hostname has the |
| highest priority, calling this function usually affects also the <varname>Hostname</varname> property |
| and the effective hostname configured in the kernel.</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><function>Describe()</function> returns a JSON representation of all properties in one.</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>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 a suitable |
| fallback.</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> |