systemd/man/nss-resolve.xml

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<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
  "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">

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  Copyright 2013 Tom Gundersen

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<refentry id="nss-resolve" conditional='ENABLE_RESOLVED'>

  <refentryinfo>
    <title>nss-resolve</title>
    <productname>systemd</productname>

    <authorgroup>
      <author>
        <contrib>Developer</contrib>
        <firstname>Lennart</firstname>
        <surname>Poettering</surname>
        <email>lennart@poettering.net</email>
      </author>
    </authorgroup>
  </refentryinfo>

  <refmeta>
    <refentrytitle>nss-resolve</refentrytitle>
    <manvolnum>8</manvolnum>
  </refmeta>

  <refnamediv>
    <refname>nss-resolve</refname>
    <refname>libnss_resolve.so.2</refname>
    <refpurpose>Provide hostname resolution via <filename>systemd-resolved.service</filename></refpurpose>
  </refnamediv>

  <refsynopsisdiv>
    <para><filename>libnss_resolve.so.2</filename></para>
  </refsynopsisdiv>

  <refsect1>
    <title>Description</title>

    <para><command>nss-resolve</command> is a plugin module for the
    GNU Name Service Switch (NSS) functionality of the GNU C Library
    (<command>glibc</command>) enabling it to resolve host names via
    the
    <citerefentry><refentrytitle>systemd-resolved</refentrytitle><manvolnum>8</manvolnum></citerefentry>
    local network name resolution service.</para>

    <para>To activate the NSS module, <literal>resolve</literal>
    has to be added to the line starting with
    <literal>hosts:</literal> in
    <filename>/etc/nsswitch.conf</filename>.</para>

    <para>It is recommended to place <literal>resolve</literal> early
    in the <filename>nsswitch.conf</filename> line (but after the
    <literal>files</literal> entry), replacing the
    <literal>dns</literal> entry if it exists, to ensure DNS queries
    are always routed via
    <citerefentry><refentrytitle>systemd-resolved</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
  </refsect1>

  <refsect1>
    <title>Example</title>

    <para>Here is an example <filename>/etc/nsswitch.conf</filename>
    file that enables <command>resolve</command> correctly:</para>

<programlisting>passwd:         compat mymachines
group:          compat mymachines
shadow:         compat

hosts:          files <command>resolve</command> mymachines myhostname
networks:       files

protocols:      db files
services:       db files
ethers:         db files
rpc:            db files

netgroup:       nis</programlisting>

    <para>Note that <command>nss-resolve</command> will chain-load
    <command>nss-dns</command> if
    <filename>systemd-resolved.service</filename> is not running,
    ensuring that basic DNS resolution continues to work if the
    service is down.</para>

  </refsect1>

  <refsect1>
    <title>See Also</title>
    <para>
      <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
      <citerefentry><refentrytitle>systemd-resolved</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
      <citerefentry><refentrytitle>nss-mymachines</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
      <citerefentry><refentrytitle>nss-myhostname</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
      <citerefentry project='man-pages'><refentrytitle>nsswitch.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>
    </para>
  </refsect1>

</refentry>