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Attempt to clarify LSM some more

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Tom Eastep 2009-10-08 14:05:46 -07:00
parent 3f7a1f9574
commit 7612c895e5
1 changed files with 99 additions and 19 deletions
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docs/MultiISP.xml
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@ -1363,19 +1363,85 @@ fi</programlisting></para>
supported. This allows additional files to be sourced in from the main
configuration file.</para>
<para>LSM monitors the status of the links defined in its
configuration file and runs a user-provided script when the status of
a link changes. The script name is specified in the
<firstterm>eventscript</firstterm> option in the configuration file.
Key arguments to the script are as follows:</para>
<variablelist>
<varlistentry>
<term>$1</term>
<listitem>
<para>The state of the link ('up' or 'down')</para>
</listitem>
</varlistentry>
<varlistentry>
<term>$2</term>
<listitem>
<para>The name of the connection as specified in the
configuration file.</para>
</listitem>
</varlistentry>
<varlistentry>
<term>$4</term>
<listitem>
<para>The name of the network interface associated with the
connection.</para>
</listitem>
</varlistentry>
<varlistentry>
<term>$5</term>
<listitem>
<para>The email address of the person specified to receive
notifications. Specified in the
<firstterm>warn_email</firstterm> option in the configuration
file.</para>
</listitem>
</varlistentry>
</variablelist>
<para>It is the responsibility of the script to perform any action
needed in reaction to the connection state change. The default script
supplied with LSM composes an email and sends it to $5. </para>
<para>I personally use LSM here at shorewall.net (configuration is
described <link linkend="Complete">below</link>). I have set things up
so that Shorewall [re]starts lsm during processing of the
<command>start</command> and <command>restore</command> commands. I
don't have Shorewall restart lsm during Shorewall
<command>restart</command> because I restart Shorewall much more often
than the average user is likely to do. I have Shorewall start lsm
because I have a dynamic IP address from one of my providers
(Comcast); Shorewall detects the default gateway to that provider and
creates a secondary configuration file
(<filename>/etc/lsm/shorewall.conf</filename>) that contains the link
configurations. That file is included by
<filename>/etc/lsm/lsm.conf</filename>.B</para>
so that:</para>
<itemizedlist>
<listitem>
<para>Shorewall [re]starts lsm during processing of the
<command>start</command> and <command>restore</command> commands.
I don't have Shorewall restart lsm during Shorewall
<command>restart</command> because I restart Shorewall much more
often than the average user is likely to do.</para>
</listitem>
<listitem>
<para>Shorewall starts lsm because I have a dynamic IP address
from one of my providers (Comcast); Shorewall detects the default
gateway to that provider and creates a secondary configuration
file (<filename>/etc/lsm/shorewall.conf</filename>) that contains
the link configurations. That file is included by
<filename>/etc/lsm/lsm.conf</filename>.</para>
</listitem>
<listitem>
<para>The script run by LSM during state change
(<filename>/etc/lsm/script) </filename>writes a<filename>
${VARDIR}/xxx.status</filename> file when the status of an
interface changes. Those files are read by the
<filename>isusable</filename> extension script (see below).</para>
</listitem>
</itemizedlist>
<para>Below are my relevant configuration files.</para>
@ -1386,12 +1452,10 @@ fi</programlisting></para>
<para><filename>/etc/shorewall/isusable</filename>:</para>
<para>Note that <filename>/etc/lsm/script </filename>writes
a<filename> ${VARDIR}/xxx.status</filename> file when the status of an
interface changes.</para>
<programlisting>local status=0
#
# Read the status file (if any) created by /etc/lsm/script
#
[ -f ${VARDIR}/${1}.status ] &amp;&amp; status=$(cat ${VARDIR}/${1}.status)
return $status</programlisting>
@ -1404,7 +1468,16 @@ return $status</programlisting>
# Start lsm
###############################################################################
start_lsm() {
#
# Kill any existing lsm process(es)
#
killall lsm 2&gt; /dev/null
#
# Create the Shorewall-specific part of the LSM configuration. This file is
# included by /etc/lsm/lsm.conf
#
# Avvanta has a static gateway while Comcast's is dynamic
#
cat &lt;&lt;EOF &gt; /etc/lsm/shorewall.conf
connection {
name=Avvanta
@ -1420,13 +1493,20 @@ connection {
ttl=1
}
EOF
#
# Since LSM assumes that interfaces start in the 'up' state, remove any
# existing status files that might have an interface in the down state
#
rm -f /etc/shorewall/*.status
#
# Run LSM -- by default, it forks into the background
#
/usr/sbin/lsm /etc/lsm/lsm.conf &gt;&gt; /var/log/lsm
}</programlisting>
<para>eth3 has a dynamic IP address so I need to use the
Shorewall-detected gateway address ($ETH3_GATEWAY). I supply a default
value in the event that detection fails.</para>
value to be used in the event that detection fails.</para>
<para><filename>/etc/shorewall/started</filename>:</para>
@ -1532,11 +1612,11 @@ EOM
echo $state &gt; ${VARDIR}/${DEVICE}.status
/sbin/shorewall -f restart &gt;&gt; /var/log/lsm 2&gt;&amp;1
/sbin/shorewall restart -f &gt;&gt; /var/log/lsm 2&gt;&amp;1
/sbin/shorewall show routing &gt;&gt; /var/log/lsm
exit 0;
exit 0
#EOF</programlisting>:</para>
</section>