man/nss-systemd.xml

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   2 <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
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   5 <!--
   6   SPDX-License-Identifier: LGPL-2.1+
   7
   8   Copyright 2016 Lennart Poettering
   9 -->
  10
  11 <refentry id="nss-systemd" conditional='ENABLE_NSS_SYSTEMD'>
  12
  13   <refentryinfo>
  14     <title>nss-systemd</title>
  15     <productname>systemd</productname>
  16
  17     <authorgroup>
  18       <author>
  19         <contrib>Developer</contrib>
  20         <firstname>Lennart</firstname>
  21         <surname>Poettering</surname>
  22         <email>lennart@poettering.net</email>
  23       </author>
  24     </authorgroup>
  25   </refentryinfo>
  26
  27   <refmeta>
  28     <refentrytitle>nss-systemd</refentrytitle>
  29     <manvolnum>8</manvolnum>
  30   </refmeta>
  31
  32   <refnamediv>
  33     <refname>nss-systemd</refname>
  34     <refname>libnss_systemd.so.2</refname>
  35     <refpurpose>Provide UNIX user and group name resolution for dynamic users and groups.</refpurpose>
  36   </refnamediv>
  37
  38   <refsynopsisdiv>
  39     <para><filename>libnss_systemd.so.2</filename></para>
  40   </refsynopsisdiv>
  41
  42   <refsect1>
  43     <title>Description</title>
  44
  45     <para><command>nss-systemd</command> is a plug-in module for the GNU Name Service Switch (NSS) functionality of the
  46     GNU C Library (<command>glibc</command>), providing UNIX user and group name resolution for dynamic users and
  47     groups allocated through the <varname>DynamicUser=</varname> option in systemd unit files. See
  48     <citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry> for details on
  49     this option.</para>
  50
  51     <para>This module also ensures that the root and nobody users and groups (i.e. the users/groups with the UIDs/GIDs
  52     0 and 65534) remain resolvable at all times, even if they aren't listed in <filename>/etc/passwd</filename> or
  53     <filename>/etc/group</filename>, or if these files are missing.</para>
  54
  55     <para>To activate the NSS module, add <literal>systemd</literal> to the lines starting with
  56     <literal>passwd:</literal> and <literal>group:</literal> in <filename>/etc/nsswitch.conf</filename>.</para>
  57
  58     <para>It is recommended to place <literal>systemd</literal> after the <literal>files</literal> or
  59     <literal>compat</literal> entry of the <filename>/etc/nsswitch.conf</filename> lines so that
  60     <filename>/etc/passwd</filename> and <filename>/etc/group</filename> based mappings take precedence.</para>
  61   </refsect1>
  62
  63   <refsect1>
  64     <title>Example</title>
  65
  66     <para>Here is an example <filename>/etc/nsswitch.conf</filename> file that enables
  67     <command>nss-systemd</command> correctly:</para>
  68
  69     <programlisting>passwd:         compat mymachines <command>systemd</command>
  70 group:          compat mymachines <command>systemd</command>
  71 shadow:         compat
  72
  73 hosts:          files mymachines resolve [!UNAVAIL=return] dns myhostname
  74 networks:       files
  75
  76 protocols:      db files
  77 services:       db files
  78 ethers:         db files
  79 rpc:            db files
  80
  81 netgroup:       nis</programlisting>
  82
  83   </refsect1>
  84
  85   <refsect1>
  86     <title>See Also</title>
  87     <para>
  88       <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
  89       <citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
  90       <citerefentry><refentrytitle>nss-resolve</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
  91       <citerefentry><refentrytitle>nss-myhostname</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
  92       <citerefentry><refentrytitle>nss-mymachines</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
  93       <citerefentry project='man-pages'><refentrytitle>nsswitch.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
  94       <citerefentry project='man-pages'><refentrytitle>getent</refentrytitle><manvolnum>1</manvolnum></citerefentry>
  95     </para>
  96   </refsect1>
  97
  98 </refentry>