<refnamediv>
<refname>nss-myhostname</refname>
- <refpurpose>Provide host name resolution for the locally
+ <refname>libnss_myhostname.so.2</refname>
+ <refpurpose>Provide hostname resolution for the locally
configured system hostname.</refpurpose>
</refnamediv>
<refsynopsisdiv>
- <para><filename>nss-myhostname.la</filename></para>
+ <para><filename>libnss_myhostname.so.2</filename></para>
</refsynopsisdiv>
<refsect1>
<title>Description</title>
- <para><command>nss-myhostname</command> is a plugin for the GNU Name Service Switch
- (NSS) functionality of the GNU C Library (<command>glibc</command>)
- providing host name resolution for the locally configured system
- hostname as returned by
- <citerefentry><refentrytitle>gethostname</refentrytitle><manvolnum>2</manvolnum></citerefentry>.
- Various software relies on an always resolvable local host name. When
- using dynamic hostnames this is usually achieved by patching
- <filename>/etc/hosts</filename> at the same time as changing the host
- name. This however is not ideal since it requires a writable
- <filename>/etc</filename> file system and is fragile because the file
- might be edited by the administrator at the same time. <command>nss-myhostname</command>
- simply returns all locally configure public IP addresses, or -- if none
- are configured -- the IPv4 address 127.0.0.2 (which is on the local
- loopback) and the IPv6 address ::1 (which is the local host) for
- whatever system hostname is configured locally. Patching
- <filename>/etc/hosts</filename> is thus no longer necessary.</para>
-
- <para>To activate the NSS modules, <option>myhostname</option>
- has to be added to the line starting with "<varname>hosts:</varname>" in
- <filename>/etc/nsswitch.conf</filename></para>
-
- <para>It is recommended to put <option>myhostname</option>
- last in the <filename>nsswitch.conf</filename> line to make
- sure that this mapping is only used as fallback, and any DNS
- or <filename>/etc/hosts</filename> based mapping takes precedence.</para>
+ <para><command>nss-myhostname</command> is a plugin
+ for the GNU Name Service Switch (NSS) functionality of
+ the GNU C Library (<command>glibc</command>) primarily
+ providing hostname resolution for the locally
+ configured system hostname as returned by
+ <citerefentry><refentrytitle>gethostname</refentrytitle><manvolnum>2</manvolnum></citerefentry>. The
+ precise hostnames resolved by this module are:</para>
+
+ <itemizedlist>
+ <listitem><para>The local, configured hostname
+ is resolved to all locally configured IP
+ addresses ordered by their scope, or -- if
+ none are configured -- the IPv4 address
+ 127.0.0.2 (which is on the local loopback) and
+ the IPv6 address ::1 (which is the local
+ host).</para></listitem>
+
+ <listitem><para>The hostname
+ <literal>localhost</literal> is resolved to
+ the IP addresses 127.0.0.1 and
+ ::1.</para></listitem>
+
+ <listitem><para>The hostname
+ <literal>gateway</literal> is resolved to all
+ current default routing gateway addresses,
+ ordered by their metric. This assigns a stable
+ hostname to the current gateway, useful for
+ referencing it independently of the current
+ network configuration state.</para></listitem>
+
+ </itemizedlist>
+
+ <para>Various software relies on an always-resolvable
+ local hostname. When using dynamic hostnames, this is
+ traditionally achieved by patching
+ <filename>/etc/hosts</filename> at the same time as
+ changing the hostname. This is problematic since it
+ requires a writable <filename>/etc</filename> file
+ system and is fragile because the file might be edited
+ by the administrator at the same time. With
+ <command>nss-myhostname</command> enabled changing
+ <filename>/etc/hosts</filename> is unncessary, and on
+ many systems the file becomes entirely optional.</para>
+
+ <para>To activate the NSS modules,
+ <literal>myhostname</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>myhostname</literal> last in the
+ <filename>nsswitch.conf</filename> line to make sure
+ that this mapping is only used as fallback, and any
+ DNS or <filename>/etc/hosts</filename> based mapping
+ takes precedence.</para>
</refsect1>
<refsect1>
<title>Example</title>
- <programlisting>
-# /etc/nsswitch.conf
+ <para>Here's an example
+ <filename>/etc/nsswitch.conf</filename> file, that
+ enables <command>myhostname</command>
+ correctly:</para>
-passwd: compat
+<programlisting>passwd: compat
group: compat
shadow: compat
-hosts: files dns <varname>myhostname</varname>
+hosts: files dns mymachines <command>myhostname</command>
networks: files
protocols: db files
ethers: db files
rpc: db files
-netgroup: nis
- </programlisting>
+netgroup: nis</programlisting>
<para>To test, use <command>glibc</command>'s <command>getent</command> tool:</para>
- <programlisting>
-$ getent ahosts `hostname`
+ <programlisting>$ getent ahosts `hostname`
::1 STREAM omega
::1 DGRAM
::1 RAW
127.0.0.2 STREAM
127.0.0.2 DGRAM
-127.0.0.2 RAW
- </programlisting>
+127.0.0.2 RAW</programlisting>
- <para>In this case the local host name is <varname>omega</varname>.</para>
+ <para>In this case the local hostname is <varname>omega</varname>.</para>
</refsect1>
<title>See Also</title>
<para>
<citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
- <citerefentry><refentrytitle>systemd-logind.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
- <citerefentry><refentrytitle>logind.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
- <citerefentry><refentrytitle>loginctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
- <citerefentry><refentrytitle>pam.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
- <citerefentry><refentrytitle>pam.d</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
- <citerefentry><refentrytitle>pam</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
- <citerefentry><refentrytitle>pam_loginuid</refentrytitle><manvolnum>8</manvolnum></citerefentry>
+ <citerefentry><refentrytitle>nss-mymachines</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
+ <citerefentry project='man-pages'><refentrytitle>nsswitch.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
+ <citerefentry project='man-pages'><refentrytitle>getent</refentrytitle><manvolnum>1</manvolnum></citerefentry>
</para>
</refsect1>
~ianmdlvl / elogind.git / blobdiff