X-Git-Url: http://www.chiark.greenend.org.uk/ucgi/~ianmdlvl/git?p=elogind.git;a=blobdiff_plain;f=man%2Fsysctl.d.xml;h=c67a199fb518513e39677a66ac59c1f805346fea;hp=db53b495998b27671662d0c31619305a6fd93670;hb=302fbdf29eb0ad4ca1fe8ee18755edad7db11b37;hpb=2e573fcf8754fdfe0db0a783b1631ec1679b063a

diff --git a/man/sysctl.d.xml b/man/sysctl.d.xml
index db53b4959..c67a199fb 100644
--- a/man/sysctl.d.xml
+++ b/man/sysctl.d.xml
@@ -1,5 +1,4 @@
-<?xml version="1.0"?>
-<!--*-nxml-*-->
+<?xml version="1.0"?> <!--*-nxml-*-->
 <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN" "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
 <!--
   This file is part of systemd.
@@ -19,7 +18,8 @@
   You should have received a copy of the GNU Lesser General Public License
   along with systemd; If not, see <http://www.gnu.org/licenses/>.
 -->
-<refentry id="sysctl.d">
+<refentry id="sysctl.d"
+          xmlns:xi="http://www.w3.org/2001/XInclude">
 
         <refentryinfo>
                 <title>sysctl.d</title>
@@ -89,34 +89,6 @@
                 <filename>/proc/sys/net/ipv4/conf/enp3s0.200/forwarding</filename>.
                 </para>
 
-                <para>Each configuration file shall be named in the
-                style of <filename><replaceable>program</replaceable>.conf</filename>.
-                Files in <filename>/etc/</filename> override files
-                with the same name in <filename>/usr/lib/</filename>
-                and <filename>/run/</filename>.  Files in
-                <filename>/run/</filename> override files with the same
-                name in <filename>/usr/lib/</filename>. Packages
-                should install their configuration files in
-                <filename>/usr/lib/</filename>. Files in
-                <filename>/etc/</filename> are reserved for the local
-                administrator, who may use this logic to override the
-                configuration files installed by vendor packages. All
-                configuration files are sorted by their filename in
-                lexicographic order, regardless of which of the
-                directories they reside in. If multiple files specify the
-                same variable name, the entry in the file with the
-                lexicographically latest name will be applied. It is
-                recommended to prefix all filenames with a two-digit
-                number and a dash, to simplify the ordering of the
-                files.</para>
-
-                <para>If the administrator wants to disable a
-                configuration file supplied by the vendor, the
-                recommended way is to place a symlink to
-                <filename>/dev/null</filename> in
-                <filename>/etc/sysctl.d/</filename> bearing the
-                same filename.</para>
-
                 <para>The settings configured with
                 <filename>sysctl.d</filename> files will be applied
                 early on boot. The network interface-specific options
@@ -125,16 +97,67 @@
                 specifically,
                 <filename>net.ipv4.conf.*</filename>,
                 <filename>net.ipv6.conf.*</filename>,
-                <filename>net.ipv4.neigh.*</filename> and <filename>net.ipv6.neigh.*</filename>)</para>
+                <filename>net.ipv4.neigh.*</filename> and <filename>net.ipv6.neigh.*</filename>).</para>
+
+                <para>Many sysctl parameters only become available
+                when certain kernel modules are loaded. Modules are
+                usually loaded on demand, e.g. when certain hardware
+                is plugged in or network brought up. This means that
+                <citerefentry><refentrytitle>systemd-sysctl.service</refentrytitle><manvolnum>8</manvolnum></citerefentry> which runs
+                during early boot will not configure such parameters
+                if they become available after it has run. To
+                set such parameters, it is recommended to add
+                an <citerefentry><refentrytitle>udev</refentrytitle><manvolnum>7</manvolnum></citerefentry> rule to set those parameters when they become
+                available. Alternatively, a slightly simpler and
+                less efficient option is to add the module to
+                <citerefentry><refentrytitle>modules-load.d</refentrytitle><manvolnum>5</manvolnum></citerefentry>, causing it to be loaded statically
+                before sysctl settings are applied (see
+                example below).</para>
         </refsect1>
 
+        <xi:include href="standard-conf.xml" xpointer="confd" />
+
         <refsect1>
-                <title>Example</title>
+                <title>Examples</title>
+                <example>
+                        <title>Set kernel YP domain name</title>
+                        <para><filename>/etc/sysctl.d/domain-name.conf</filename>:
+                        </para>
+
+                        <programlisting>kernel.domainname=example.com</programlisting>
+                </example>
+
+                <example>
+                        <title>Disable packet filter on bridged packets (method one)</title>
+                        <para><filename>/etc/udev/rules.d/99-bridge.rules</filename>:
+                        </para>
+
+                        <programlisting>ACTION=="add", SUBSYSTEM=="module", KERNEL=="bridge", RUN+="/usr/lib/systemd/systemd-sysctl --prefix=/net/bridge"
+</programlisting>
+
+                        <para><filename>/etc/sysctl.d/bridge.conf</filename>:
+                        </para>
+
+                        <programlisting>net.bridge.bridge-nf-call-ip6tables = 0
+net.bridge.bridge-nf-call-iptables = 0
+net.bridge.bridge-nf-call-arptables = 0
+</programlisting>
+                </example>
+
                 <example>
-                        <title>/etc/sysctl.d/domain-name.conf example:</title>
+                        <title>Disable packet filter on bridged packets (method two)</title>
+                        <para><filename>/etc/modules-load.d/bridge.conf</filename>:
+                        </para>
+
+                        <programlisting>bridge</programlisting>
+
+                        <para><filename>/etc/sysctl.d/bridge.conf</filename>:
+                        </para>
 
-                        <programlisting># Set kernel YP domain name
-kernel.domainname=example.com</programlisting>
+                        <programlisting>net.bridge.bridge-nf-call-ip6tables = 0
+net.bridge.bridge-nf-call-iptables = 0
+net.bridge.bridge-nf-call-arptables = 0
+</programlisting>
                 </example>
         </refsect1>
 
@@ -145,7 +168,8 @@ kernel.domainname=example.com</programlisting>
                         <citerefentry><refentrytitle>systemd-sysctl.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
                         <citerefentry><refentrytitle>systemd-delta</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
                         <citerefentry><refentrytitle>sysctl</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
-                        <citerefentry><refentrytitle>sysctl.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>
+                        <citerefentry><refentrytitle>sysctl.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
+                        <citerefentry><refentrytitle>modprobe</refentrytitle><manvolnum>8</manvolnum></citerefentry>
                 </para>
         </refsect1>