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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 | <!-- | |
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6 | SPDX-License-Identifier: LGPL-2.1+ |
7 | ||
96b2fb93 | 8 | Copyright © 2013 Tom Gundersen |
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9 | --> |
10 | ||
1ec57f33 | 11 | <refentry id="nss-resolve" conditional='ENABLE_RESOLVE'> |
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12 | |
13 | <refentryinfo> | |
14 | <title>nss-resolve</title> | |
15 | <productname>systemd</productname> | |
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16 | </refentryinfo> |
17 | ||
18 | <refmeta> | |
19 | <refentrytitle>nss-resolve</refentrytitle> | |
20 | <manvolnum>8</manvolnum> | |
21 | </refmeta> | |
22 | ||
23 | <refnamediv> | |
24 | <refname>nss-resolve</refname> | |
25 | <refname>libnss_resolve.so.2</refname> | |
26 | <refpurpose>Provide hostname resolution via <filename>systemd-resolved.service</filename></refpurpose> | |
27 | </refnamediv> | |
28 | ||
29 | <refsynopsisdiv> | |
30 | <para><filename>libnss_resolve.so.2</filename></para> | |
31 | </refsynopsisdiv> | |
32 | ||
33 | <refsect1> | |
34 | <title>Description</title> | |
35 | ||
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36 | <para><command>nss-resolve</command> is a plug-in module for the GNU Name Service Switch (NSS) functionality of the |
37 | GNU C Library (<command>glibc</command>) enabling it to resolve host names via the | |
38 | <citerefentry><refentrytitle>systemd-resolved</refentrytitle><manvolnum>8</manvolnum></citerefentry> local network | |
39 | name resolution service. It replaces the <command>nss-dns</command> plug-in module that traditionally resolves | |
40 | hostnames via DNS.</para> | |
41 | ||
42 | <para>To activate the NSS module, add <literal>resolve</literal> to the line starting with | |
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43 | <literal>hosts:</literal> in <filename>/etc/nsswitch.conf</filename>. Specifically, it is recommended to place |
44 | <literal>resolve</literal> early in <filename>/etc/nsswitch.conf</filename>'s <literal>hosts:</literal> line (but | |
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45 | after the <literal>files</literal> or <literal>mymachines</literal> entries), right before the |
46 | <literal>dns</literal> entry if it exists, followed by <literal>[!UNAVAIL=return]</literal>, to ensure DNS queries | |
47 | are always routed via | |
48 | <citerefentry><refentrytitle>systemd-resolved</refentrytitle><manvolnum>8</manvolnum></citerefentry> if it is | |
49 | running, but are routed to <command>nss-dns</command> if this service is not available.</para> | |
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50 | |
51 | <para>Note that <command>systemd-resolved</command> will synthesize DNS resource | |
25fb19da | 52 | records in a few cases, for example for <literal>localhost</literal> and the |
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53 | current hostname, see |
54 | <citerefentry><refentrytitle>systemd-resolved</refentrytitle><manvolnum>8</manvolnum></citerefentry> | |
55 | for the full list. This duplicates the functionality of | |
56 | <citerefentry><refentrytitle>nss-myhostname</refentrytitle><manvolnum>8</manvolnum></citerefentry>, | |
57 | but it is still recommended (see examples below) to keep | |
58 | <command>nss-myhostname</command> configured in | |
59 | <filename>/etc/nsswitch.conf</filename>, to keep those names resolveable if | |
60 | <command>systemd-resolved</command> is not running.</para> | |
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61 | </refsect1> |
62 | ||
63 | <refsect1> | |
64 | <title>Example</title> | |
65 | ||
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66 | <para>Here is an example <filename>/etc/nsswitch.conf</filename> file that enables <command>nss-resolve</command> |
67 | correctly:</para> | |
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69 | <programlisting>passwd: compat mymachines systemd |
70 | group: compat mymachines systemd | |
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71 | shadow: compat |
72 | ||
75555c28 | 73 | hosts: files mymachines <command>resolve [!UNAVAIL=return]</command> dns myhostname |
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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> | |
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82 | </refsect1> |
83 | ||
84 | <refsect1> | |
85 | <title>See Also</title> | |
86 | <para> | |
87 | <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>, | |
88 | <citerefentry><refentrytitle>systemd-resolved</refentrytitle><manvolnum>8</manvolnum></citerefentry>, | |
409093fe | 89 | <citerefentry><refentrytitle>nss-systemd</refentrytitle><manvolnum>8</manvolnum></citerefentry>, |
0d6868f9 | 90 | <citerefentry><refentrytitle>nss-myhostname</refentrytitle><manvolnum>8</manvolnum></citerefentry>, |
409093fe | 91 | <citerefentry><refentrytitle>nss-mymachines</refentrytitle><manvolnum>8</manvolnum></citerefentry>, |
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92 | <citerefentry project='man-pages'><refentrytitle>nsswitch.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry> |
93 | </para> | |
94 | </refsect1> | |
95 | ||
96 | </refentry> |