man/nss-resolve.xml

   1 <?xml version='1.0'?> <!--*- Mode: nxml; nxml-child-indent: 2; indent-tabs-mode: nil -*-->
   2 <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
   3   "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
   4
   5 <!--
   6   This file is part of systemd.
   7
   8   Copyright 2011 Lennart Poettering
   9   Copyright 2013 Tom Gundersen
  10
  11   systemd is free software; you can redistribute it and/or modify it
  12   under the terms of the GNU Lesser General Public License as published by
  13   the Free Software Foundation; either version 2.1 of the License, or
  14   (at your option) any later version.
  15
  16   systemd is distributed in the hope that it will be useful, but
  17   WITHOUT ANY WARRANTY; without even the implied warranty of
  18   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  19   Lesser General Public License for more details.
  20
  21   You should have received a copy of the GNU Lesser General Public License
  22   along with systemd; If not, see <http://www.gnu.org/licenses/>.
  23 -->
  24
  25 <refentry id="nss-resolve" conditional='ENABLE_RESOLVED'>
  26
  27   <refentryinfo>
  28     <title>nss-resolve</title>
  29     <productname>systemd</productname>
  30
  31     <authorgroup>
  32       <author>
  33         <contrib>Developer</contrib>
  34         <firstname>Lennart</firstname>
  35         <surname>Poettering</surname>
  36         <email>lennart@poettering.net</email>
  37       </author>
  38     </authorgroup>
  39   </refentryinfo>
  40
  41   <refmeta>
  42     <refentrytitle>nss-resolve</refentrytitle>
  43     <manvolnum>8</manvolnum>
  44   </refmeta>
  45
  46   <refnamediv>
  47     <refname>nss-resolve</refname>
  48     <refname>libnss_resolve.so.2</refname>
  49     <refpurpose>Provide hostname resolution via <filename>systemd-resolved.service</filename></refpurpose>
  50   </refnamediv>
  51
  52   <refsynopsisdiv>
  53     <para><filename>libnss_resolve.so.2</filename></para>
  54   </refsynopsisdiv>
  55
  56   <refsect1>
  57     <title>Description</title>
  58
  59     <para><command>nss-resolve</command> is a plug-in module for the GNU Name Service Switch (NSS) functionality of the
  60     GNU C Library (<command>glibc</command>) enabling it to resolve host names via the
  61     <citerefentry><refentrytitle>systemd-resolved</refentrytitle><manvolnum>8</manvolnum></citerefentry> local network
  62     name resolution service. It replaces the <command>nss-dns</command> plug-in module that traditionally resolves
  63     hostnames via DNS.</para>
  64
  65     <para>To activate the NSS module, add <literal>resolve</literal> to the line starting with
  66     <literal>hosts:</literal> in <filename>/etc/nsswitch.conf</filename>. Specifcally, it is recommended to place
  67     <literal>resolve</literal> early in <filename>/etc/nsswitch.conf</filename>' <literal>hosts:</literal> line (but
  68     after the <literal>files</literal> or <literal>mymachines</literal> entries), right before the
  69     <literal>dns</literal> entry if it exists, followed by <literal>[!UNAVAIL=return]</literal>, to ensure DNS queries
  70     are always routed via
  71     <citerefentry><refentrytitle>systemd-resolved</refentrytitle><manvolnum>8</manvolnum></citerefentry> if it is
  72     running, but are routed to <command>nss-dns</command> if this service is not available.</para>
  73   </refsect1>
  74
  75   <refsect1>
  76     <title>Example</title>
  77
  78     <para>Here is an example <filename>/etc/nsswitch.conf</filename> file that enables <command>nss-resolve</command>
  79     correctly:</para>
  80
  81 <programlisting>passwd:         compat mymachines systemd
  82 group:          compat mymachines systemd
  83 shadow:         compat
  84
  85 hosts:          files mymachines <command>resolve [!UNAVAIL=return]</command> dns myhostname
  86 networks:       files
  87
  88 protocols:      db files
  89 services:       db files
  90 ethers:         db files
  91 rpc:            db files
  92
  93 netgroup:       nis</programlisting>
  94   </refsect1>
  95
  96   <refsect1>
  97     <title>See Also</title>
  98     <para>
  99       <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
 100       <citerefentry><refentrytitle>systemd-resolved</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
 101       <citerefentry><refentrytitle>nss-systemd</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
 102       <citerefentry><refentrytitle>nss-myhostname</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
 103       <citerefentry><refentrytitle>nss-mymachines</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
 104       <citerefentry project='man-pages'><refentrytitle>nsswitch.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>
 105     </para>
 106   </refsect1>
 107
 108 </refentry>