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9053aaad42
So far we recommended placing "nss-mymachines" after "nss-resolve" in the order of preference in /etc/nsswitch.conf. This change reverse this order. Rationale: single-label names are resolved via LLMNR by resolved, which has to time out if no peer by that name exists. By placing "nss-mymachines" first (which always responds immediately) we avoid running into this timeout for most containers. Both modules should return the same data if LLMNR is used by the container anyway. While we are at it, improve the man pages of the three NSS modules in other ways a bit.
114 lines
4.5 KiB
XML
114 lines
4.5 KiB
XML
<?xml version='1.0'?> <!--*-nxml-*-->
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<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
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"http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
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<!--
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This file is part of systemd.
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Copyright 2014 Lennart Poettering
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systemd is free software; you can redistribute it and/or modify it
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under the terms of the GNU Lesser General Public License as published by
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the Free Software Foundation; either version 2.1 of the License, or
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(at your option) any later version.
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systemd is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public License
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along with systemd; If not, see <http://www.gnu.org/licenses/>.
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-->
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<refentry id="nss-mymachines" conditional='ENABLE_MACHINED'>
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<refentryinfo>
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<title>nss-mymachines</title>
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<productname>systemd</productname>
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<authorgroup>
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<author>
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<contrib>Developer</contrib>
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<firstname>Lennart</firstname>
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<surname>Poettering</surname>
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<email>lennart@poettering.net</email>
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</author>
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</authorgroup>
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</refentryinfo>
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<refmeta>
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<refentrytitle>nss-mymachines</refentrytitle>
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<manvolnum>8</manvolnum>
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</refmeta>
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<refnamediv>
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<refname>nss-mymachines</refname>
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<refname>libnss_mymachines.so.2</refname>
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<refpurpose>Provide hostname resolution for local
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container instances.</refpurpose>
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</refnamediv>
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<refsynopsisdiv>
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<para><filename>libnss_mymachines.so.2</filename></para>
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</refsynopsisdiv>
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<refsect1>
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<title>Description</title>
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<para><command>nss-mymachines</command> is a plug-in module for the GNU Name Service Switch (NSS) functionality of
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the GNU C Library (<command>glibc</command>), providing hostname resolution for the names of containers running
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locally that are registered with
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<citerefentry><refentrytitle>systemd-machined.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>. The
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container names are resolved to the IP addresses of the specific container, ordered by their scope. This
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functionality only applies to containers using network namespacing.</para>
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<para>The module also resolves user and group IDs used by containers to user and group names indicating the
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container name, and back. This functionality only applies to containers using user namespacing.</para>
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<para>To activate the NSS module, add <literal>mymachines</literal> to the lines starting with
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<literal>hosts:</literal>, <literal>passwd:</literal> and <literal>group:</literal> in
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<filename>/etc/nsswitch.conf</filename>.</para>
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<para>It is recommended to place <literal>mymachines</literal> after the <literal>files</literal> or
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<literal>compat</literal> entry of the <filename>/etc/nsswitch.conf</filename> lines to make sure that its mappings
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are preferred over other resolvers such as DNS, but so that <filename>/etc/hosts</filename>,
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<filename>/etc/passwd</filename> and <filename>/etc/group</filename> based mappings take precedence.</para>
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</refsect1>
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<refsect1>
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<title>Example</title>
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<para>Here is an example <filename>/etc/nsswitch.conf</filename> file that enables
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<command>nss-mymachines</command> correctly:</para>
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<programlisting>passwd: compat <command>mymachines</command>
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group: compat <command>mymachines</command>
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shadow: compat
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hosts: files <command>mymachines</command> resolve myhostname
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networks: files
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protocols: db files
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services: db files
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ethers: db files
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rpc: db files
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netgroup: nis</programlisting>
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</refsect1>
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<refsect1>
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<title>See Also</title>
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<para>
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<citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>systemd-machined.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>nss-resolve</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>nss-myhostname</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
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<citerefentry project='man-pages'><refentrytitle>nsswitch.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
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<citerefentry project='man-pages'><refentrytitle>getent</refentrytitle><manvolnum>1</manvolnum></citerefentry>
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</para>
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</refsect1>
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</refentry>
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