1<?xml version='1.0'?> <!--*-nxml-*-->
2<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
3  "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
4<!-- SPDX-License-Identifier: LGPL-2.1-or-later -->
5
6<refentry id="systemd-homed.service" conditional='ENABLE_HOMED'>
7
8  <refentryinfo>
9    <title>systemd-homed.service</title>
10    <productname>systemd</productname>
11  </refentryinfo>
12
13  <refmeta>
14    <refentrytitle>systemd-homed.service</refentrytitle>
15    <manvolnum>8</manvolnum>
16  </refmeta>
17
18  <refnamediv>
19    <refname>systemd-homed.service</refname>
20    <refname>systemd-homed</refname>
21    <refpurpose>Home Area/User Account Manager</refpurpose>
22  </refnamediv>
23
24  <refsynopsisdiv>
25    <para><filename>systemd-homed.service</filename></para>
26    <para><filename>/usr/lib/systemd/systemd-homed</filename></para>
27  </refsynopsisdiv>
28
29  <refsect1>
30    <title>Description</title>
31
32    <para><command>systemd-homed</command> is a system service that may be used to create, remove, change or
33    inspect home areas (directories and network mounts and real or loopback block devices with a filesystem,
34    optionally encrypted).</para>
35
36    <para>Most of <command>systemd-homed</command>'s functionality is accessible through the
37    <citerefentry><refentrytitle>homectl</refentrytitle><manvolnum>1</manvolnum></citerefentry> command.</para>
38
39    <para>See the <ulink url="https://systemd.io/HOME_DIRECTORY">Home Directories</ulink> documentation for
40    details about the format and design of home areas managed by
41    <filename>systemd-homed.service</filename>.</para>
42
43    <para>Each home directory managed by <filename>systemd-homed.service</filename> synthesizes a local user
44    and group. These are made available to the system using the <ulink
45    url="https://systemd.io/USER_GROUP_API">User/Group Record Lookup API via Varlink</ulink>, and thus may be
46    browsed with
47    <citerefentry><refentrytitle>userdbctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>.</para>
48  </refsect1>
49
50  <refsect1>
51    <title>Key Management</title>
52
53    <para>User records are cryptographically signed with a public/private key pair (the signature is part of
54    the JSON record itself). For a user to be permitted to log in locally the public key matching the
55    signature of their user record must be installed. For a user record to be modified locally the private
56    key matching the signature must be installed locally, too. The keys are stored in the
57    <filename>/var/lib/systemd/home/</filename> directory:</para>
58
59    <variablelist>
60
61      <varlistentry>
62        <term><filename>/var/lib/systemd/home/local.private</filename></term>
63
64        <listitem><para>The private key of the public/private key pair used for local records. Currently,
65        only a single such key may be installed.</para></listitem>
66      </varlistentry>
67
68      <varlistentry>
69        <term><filename>/var/lib/systemd/home/local.public</filename></term>
70
71        <listitem><para>The public key of the public/private key pair used for local records. Currently,
72        only a single such key may be installed.</para></listitem>
73      </varlistentry>
74
75      <varlistentry>
76        <term><filename>/var/lib/systemd/home/*.public</filename></term>
77
78        <listitem><para>Additional public keys. Any users whose user records are signed with any of these keys
79        are permitted to log in locally. An arbitrary number of keys may be installed this
80        way.</para></listitem>
81      </varlistentry>
82    </variablelist>
83
84    <para>All key files listed above are in PEM format.</para>
85
86    <para>In order to migrate a home directory from a host <literal>foobar</literal> to another host
87    <literal>quux</literal> it is hence sufficient to copy
88    <filename>/var/lib/systemd/home/local.public</filename> from the host <literal>foobar</literal> to
89    <literal>quux</literal>, maybe calling the file on the destination <filename
90    index="false">/var/lib/systemd/home/foobar.public</filename>, reflecting the origin of the key. If the
91    user record should be modifiable on <literal>quux</literal> the pair
92    <filename>/var/lib/systemd/home/local.public</filename> and
93    <filename>/var/lib/systemd/home/local.private</filename> need to be copied from <literal>foobar</literal>
94    to <literal>quux</literal>, and placed under the identical paths there, as currently only a single
95    private key is supported per host. Note of course that the latter means that user records
96    generated/signed before the key pair is copied in, lose their validity.</para>
97  </refsect1>
98
99  <refsect1>
100    <title>See Also</title>
101    <para>
102      <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
103      <citerefentry><refentrytitle>homed.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
104      <citerefentry><refentrytitle>homectl</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
105      <citerefentry><refentrytitle>pam_systemd_home</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
106      <citerefentry><refentrytitle>userdbctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
107      <citerefentry><refentrytitle>org.freedesktop.home1</refentrytitle><manvolnum>5</manvolnum></citerefentry>
108    </para>
109  </refsect1>
110</refentry>
111