# org.freedesktop.hostname1

## NAME



           org.freedesktop.hostname1 - The D-Bus interface of
           systemd-hostnamed
    


## INTRODUCTION



           systemd-hostnamed.service(8) 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.
    


## THE D-BUS API



           The service exposes the following interfaces on the bus:
    
               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);
                     GetHardwareSerial(out s serial);
                     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 t OperatingSystemSupportEnd = ...;
                     @org.freedesktop.DBus.Property.EmitsChangedSignal("const")
                     readonly s HomeURL = '...';
                     @org.freedesktop.DBus.Property.EmitsChangedSignal("const")
                     readonly s OperatingSystemImageID = '...';
                     @org.freedesktop.DBus.Property.EmitsChangedSignal("const")
                     readonly s OperatingSystemImageVersion = '...';
                     @org.freedesktop.DBus.Property.EmitsChangedSignal("const")
                     readonly s HardwareVendor = '...';
                     @org.freedesktop.DBus.Property.EmitsChangedSignal("const")
                     readonly s HardwareModel = '...';
                     @org.freedesktop.DBus.Property.EmitsChangedSignal("const")
                     readonly s HardwareSKU = '...';
                     @org.freedesktop.DBus.Property.EmitsChangedSignal("const")
                     readonly s HardwareVersion = '...';
                     @org.freedesktop.DBus.Property.EmitsChangedSignal("const")
                     readonly s FirmwareVersion = '...';
                     @org.freedesktop.DBus.Property.EmitsChangedSignal("const")
                     readonly s FirmwareVendor = '...';
                     @org.freedesktop.DBus.Property.EmitsChangedSignal("const")
                     readonly t FirmwareDate = ...;
                     @org.freedesktop.DBus.Property.EmitsChangedSignal("const")
                     readonly ay MachineID = [...];
                     @org.freedesktop.DBus.Property.EmitsChangedSignal("const")
                     readonly ay BootID = [...];
                     @org.freedesktop.DBus.Property.EmitsChangedSignal("const")
                     readonly u VSockCID = ...;
                     @org.freedesktop.DBus.Property.EmitsChangedSignal("const")
                     readonly s ChassisAssetTag = '...';
                 };
                 interface org.freedesktop.DBus.Peer { ... };
                 interface org.freedesktop.DBus.Introspectable { ... };
                 interface org.freedesktop.DBus.Properties { ... };
               };
    
           Whenever the hostname or other metadata is changed via the daemon,
           **PropertyChanged** signals are sent out to subscribed clients.
           Changing a hostname using this interface is authenticated via
           **polkit******[1].


## SEMANTICS



           The _StaticHostname_ property exposes the "static" hostname
           configured in /etc/hostname. It is not always in sync with the
           current hostname as returned by the **gethostname**(3) system call. If
           no static hostname is configured this property will be the empty
           string.
    
           When systemd(1) or systemd-hostnamed.service(8) set the hostname,
           this static hostname _has the highest priority_.
    
           The _Hostname_ property exposes the actual hostname configured in
           the kernel via sethostname(2). It can be different from the static
           hostname. This property is never empty.
    
           The _PrettyHostname_ property exposes the _pretty hostname_ 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 "Lennart’s
           Computer" the latter should be "lennarts-computer". 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.
    
           The _DefaultHostname_ property exposes the default hostname
           (configured through os-release(5), or a fallback set at
           compilation time).
    
           The _HostnameSource_ property exposes the origin of the currently
           configured hostname. One of "static" (set from /etc/hostname),
           "transient" (a non-permanent hostname from an external source),
           "default" (the value from os-release or the compiled-in fallback).
    
           The _IconName_ property exposes the _icon 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.
           "computer-laptop" vs.  "computer-desktop" 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 "computer". If this property is
           set to the empty string, the automatic fallback name selection is
           enabled again.
    
           The _Chassis_ property exposes a _chassis type_ , one of the currently
           defined chassis types: "desktop", "laptop", "server", "tablet",
           "handset", as well as the special chassis types "vm" and
           "container" 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.
    
           Note that systemd-hostnamed starts only on request and terminates
           after a short idle period. This effectively means that
           **PropertyChanged** 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.
    
           The transient (dynamic) hostname exposed by the _Hostname_ 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 **PropertyChanged** messages from
           systemd-hostnamed. To accomplish this, open
           /proc/sys/kernel/hostname and **poll**(3) for **SIGHUP** 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.
    
           Applications may read the hostname data directly if hostname
           change notifications are not necessary. Use gethostname(2),
           /etc/hostname (possibly with per-distribution fallbacks), and
           machine-info(5) for that. For more information on these files and
           syscalls see the respective man pages.
    
           _KernelName_ , _KernelRelease_ , and _KernelVersion_ expose the kernel
           name (e.g.  "Linux"), release (e.g.  "5.0.0-11"), and version
           (i.e. the build number, e.g.  "#11") as reported by uname(2).
           _OperatingSystemPrettyName_ , _OperatingSystemCPEName_ , and _HomeURL_
           expose the _PRETTY_NAME=_ , _CPE_NAME=_ and _HOME_URL=_ fields from
           os-release(5). The purpose of those properties is to allow remote
           clients to access this information over D-Bus. Local clients can
           access the information directly.
    
           _MachineID_ expose the 128bit machine ID, see machine-id(5) for
           details.
    
           _BootID_ expose the 128bit boot ID, as per
           /proc/sys/kernel/random/boot_id.
    
           _VSockCID_ exposes the system's local **AF_VSOCK** CID (Context
           Identifier, i.e. address) for the system, if one is available in
           the virtual machine environment. Set to **UINT32_MAX** otherwise. See
           vsock(7) for details.
    
           _OperatingSystemSupportEnd_ exposes when the OS' vendor support
           ends, if this information is known. It's an unsigned 64bit value,
           in µs since the UNIX epoch, UTC. If this information is not known
           carries the value 2^64-1, i.e.  **UINT64_MAX**.
    
           _OperatingSystemImageID_ and _OperatingSystemImageVersion_ expose the
           OS image name and version if available, or contain empty strings
           otherwise. This mostly corresponds to the _IMAGE_ID=_ and
           _IMAGE_VERSION=_ fields of the os-release file.
    
           _HardwareVendor_ , _HardwareModel_ , _HardwareSKU_ , and _HardwareVersion_
           expose vendor information about the hardware of the system. The
           stock keeping unit (SKU) describes a distinct type of hardware for
           sale, purchase or inventory management. The SKU and version are
           only available if they deviate from the model and among each
           other. Thereby the version is more specific and only available if
           it differs from the model and SKU. If no such information can be
           determined these properties are set to empty strings.
    
           _FirmwareVersion_ and _FirmwareVendor_ expose information about the
           system's firmware, i.e. a version string and a vendor name. If no
           such information can be determined these properties are set to
           empty strings.
    
           _FirmwareDate_ exposes the firmware build date, if that information
           is known. It's an unsigned 64bit value, in µs since the UNIX
           epoch, UTC. If not known **UNIT64_MAX**.
    
           _ChassisAssetTag_ exposes an unique identifier of the system
           chassis. If this information is not known this property is set to
           an empty string.
    
       **Methods**
           **SetHostname()** 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.
    
           **SetStaticHostname()** sets the static hostname which is exposed by
           the _StaticHostname_ property. When called with an empty argument,
           the static configuration in /etc/hostname is removed. Since the
           static hostname has the highest priority, calling this function
           usually affects also the _Hostname_ property and the effective
           hostname configured in the kernel.
    
           **SetPrettyHostname()** sets the pretty hostname which is exposed by
           the _PrettyHostname_ property.
    
           **SetIconName()** , **SetChassis()** , **SetDeployment()** , and **SetLocation()**
           set the properties _IconName_ (the name of the icon representing for
           the machine), _Chassis_ (the machine form factor), _Deployment_ (the
           system deployment environment), and _Location_ (physical system
           location), respectively.
    
           _PrettyHostname_ , _IconName_ , _Chassis_ , _Deployment_ , and _Location_ are
           stored in /etc/machine-info. See machine-info(5) for the semantics
           of those settings.
    
           **GetProductUUID()** returns the "product UUID" as exposed by the
           kernel based on DMI information in /sys/class/dmi/id/product_uuid.
           Reading the file directly requires root privileges, and this
           method allows access to unprivileged clients through the polkit
           framework.
    
           **GetHardwareSerial()** returns the "hardware serial" as exposed by
           the kernel based on DMI information. Reading the file directly
           requires root privileges, and this method allows access to
           unprivileged clients through the polkit framework.
    
           **Describe()** returns a JSON representation of all properties in one.
    
       **Security**
           The _interactive_ boolean parameters can be used to control whether
           polkit should interactively ask the user for authentication
           credentials if required.
    
           The polkit action for **SetHostname()** is
           org.freedesktop.hostname1.set-hostname. For **SetStaticHostname()**
           and **SetPrettyHostname()** it is
           org.freedesktop.hostname1.set-static-hostname. For **SetIconName()** ,
           **SetChassis()** , **SetDeployment()** and **SetLocation()** it is
           org.freedesktop.hostname1.set-machine-info.
    


## RECOMMENDATIONS



           Here are three examples that show how the pretty hostname and the
           icon name should be used:
    
           •   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.
    
           •   Set the bluetooth name to the pretty hostname.
    
           •   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.
    
           To properly handle name lookups with changing local hostnames
           without having to edit /etc/hosts, we recommend using
           systemd-hostnamed in combination with nss-myhostname(8).
    
           Here are some recommendations to follow when generating a static
           (internet) hostname from a pretty name:
    
           •   Generate a single DNS label only, not an FQDN. That means no
               dots allowed. Strip them, or replace them with "-".
    
           •   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 "a-zA-Z0-9" and "-". Strip other chars, or try to
               replace them in some smart way with chars from this set, for
               example "ä" → "ae", and use "-" as the replacement for all
               punctuation characters and whitespace.
    
           •   Try to avoid creating repeated "-", as well as "-" as the
               first or last char.
    
           •   Limit the hostname to 63 chars, which is the length of a DNS
               label.
    
           •   If after stripping special chars the empty string is the
               result, you can pass this as-is to systemd-hostnamed in which
               case it will automatically use a suitable fallback.
    
           •   Uppercase characters should be replaced with their lowercase
               equivalents.
    
           Note that while systemd-hostnamed applies some checks to the
           hostname you pass they are much looser than the recommendations
           above. For example, systemd-hostnamed will also accept "_" in the
           hostname, but we recommend not using this to avoid clashes with
           DNS-SD service types. Also systemd-hostnamed allows longer
           hostnames, but because of the DNS label limitations, we recommend
           not making use of this.
    
           Here are a couple of example conversions:
    
           •   "Lennart's PC" → "lennarts-pc"
    
           •   "Müllers Computer" → "muellers-computer"
    
           •   "Voran!"  → "voran"
    
           •   "Es war einmal ein Männlein" → "es-war-einmal-ein-maennlein"
    
           •   "Jawoll. Ist doch wahr!"  → "jawoll-ist-doch-wahr"
    
           •   "レナート" → "localhost"
    
           •   "...zack!!! zack!..."  → "zack-zack"
    
           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.
    


## EXAMPLES



           **Example 1. Introspect org.freedesktop.hostname1 on the bus**
    
               $ gdbus introspect --system \
                 --dest org.freedesktop.hostname1 \
                 --object-path /org/freedesktop/hostname1
    


## VERSIONING



           These D-Bus interfaces follow **the usual interface versioning**
           **guidelines******[2].


## NOTES



            1. polkit
               https://www.freedesktop.org/software/polkit/docs/latest/
    
            2. the usual interface versioning guidelines
               https://0pointer.de/blog/projects/versioning-dbus.html
    
            3. Feature page about xdg-hostname
               https://fedoraproject.org/wiki/Features/BetterHostname
    


* * *