shorewall_code/STABLE/documentation/shorewall_extension_scripts.htm

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<h1 align="center"><!--mstheme--><font face="times new roman, Times New Roman, Times" color="#666666">Extension Scripts<!--mstheme--></font></h1>
<p>
Extension scripts are user-provided
scripts that are invoked at various points during firewall start, restart,
stop and clear. The scripts are placed in /etc/shorewall and are processed
using the Bourne shell "source" mechanism. The following scripts can be
supplied:</p>
<!--mstheme--></font><!--msthemelist--><table border="0" cellpadding="0" cellspacing="0" width="100%">
<!--msthemelist--><tr><td valign="baseline" width="42"><img src="_themes/radial/aradbul1.gif" width="15" height="15" hspace="13" alt="bullet"></td><td valign="top" width="100%"><!--mstheme--><font face="arial, Arial, Helvetica">init -- invoked early in "shorewall start" and "shorewall restart"<!--mstheme--></font><!--msthemelist--></td></tr>
<!--msthemelist--><tr><td valign="baseline" width="42"><img src="_themes/radial/aradbul1.gif" width="15" height="15" hspace="13" alt="bullet"></td><td valign="top" width="100%"><!--mstheme--><font face="arial, Arial, Helvetica">start -- invoked after the firewall has been started or restarted.<!--mstheme--></font><!--msthemelist--></td></tr>
<!--msthemelist--><tr><td valign="baseline" width="42"><img src="_themes/radial/aradbul1.gif" width="15" height="15" hspace="13" alt="bullet"></td><td valign="top" width="100%"><!--mstheme--><font face="arial, Arial, Helvetica">stop -- invoked as a first step when the firewall is being stopped.<!--mstheme--></font><!--msthemelist--></td></tr>
<!--msthemelist--><tr><td valign="baseline" width="42"><img src="_themes/radial/aradbul1.gif" width="15" height="15" hspace="13" alt="bullet"></td><td valign="top" width="100%"><!--mstheme--><font face="arial, Arial, Helvetica">stopped -- invoked after the firewall has been stopped.<!--mstheme--></font><!--msthemelist--></td></tr>
<!--msthemelist--><tr><td valign="baseline" width="42"><img src="_themes/radial/aradbul1.gif" width="15" height="15" hspace="13" alt="bullet"></td><td valign="top" width="100%"><!--mstheme--><font face="arial, Arial, Helvetica">clear -- invoked after the firewall has been cleared.<!--mstheme--></font><!--msthemelist--></td></tr>
<!--msthemelist--><tr><td valign="baseline" width="42"><img src="_themes/radial/aradbul1.gif" width="15" height="15" hspace="13" alt="bullet"></td><td valign="top" width="100%"><!--mstheme--><font face="arial, Arial, Helvetica">refresh -- invoked while the firewall is being refreshed but before the
common and/or blacklst chains have been rebuilt.<!--mstheme--></font><!--msthemelist--></td></tr>
<!--msthemelist--><tr><td valign="baseline" width="42"><img src="_themes/radial/aradbul1.gif" width="15" height="15" hspace="13" alt="bullet"></td><td valign="top" width="100%"><!--mstheme--><font face="arial, Arial, Helvetica">newnotsyn (added in version 1.3.6) -- invoked after the 'newnotsyn' chain
has been created but before any rules have been added to it.<!--mstheme--></font><!--msthemelist--></td></tr>
<!--msthemelist--></table><!--mstheme--><font face="arial, Arial, Helvetica">
<p>
You can also supply a script with the same name as any of the filter
chains in the firewall and the script will be invoked after the /etc/shorewall/rules
file has been processed but before the /etc/shorewall/policy file has
been processed.</p>
<p>The following two files receive
special treatment:</p>
<!--mstheme--></font><!--msthemelist--><table border="0" cellpadding="0" cellspacing="0" width="100%">
<!--msthemelist--><tr><td valign="baseline" width="42"><img src="_themes/radial/aradbul1.gif" width="15" height="15" hspace="13" alt="bullet"></td><td valign="top" width="100%"><!--mstheme--><font face="arial, Arial, Helvetica">/etc/shorewall/common -- If this file is present, the rules that it
defines will totally replace the default rules in the common chain. These
default rules are contained in the file /etc/shorewall/common.def which
may be used as a starting point for making your own customized file.<!--mstheme--></font><!--msthemelist--></td></tr>
<!--msthemelist--><tr><td valign="baseline" width="42"><img src="_themes/radial/aradbul1.gif" width="15" height="15" hspace="13" alt="bullet"></td><td valign="top" width="100%"><!--mstheme--><font face="arial, Arial, Helvetica">/etc/shorewall/icmpdef -- If this file is present, the rules that it
defines will totally replace the default rules in the icmpdef chain.
These default rules are contained in the file /etc/shorewall/icmp.def
which may be used as a starting point for making your own customized
file.<!--mstheme--></font><!--msthemelist--></td></tr>
<!--msthemelist--></table><!--mstheme--><font face="arial, Arial, Helvetica">
<p>
Rather than running iptables directly, you should run it using the function
run_iptables. Similarly, rather than running "ip" directly, you should
use run_ip. These functions accept the same arguments as the underlying
command but cause the firewall to be stopped if an error occurs during
processing of the command.</p>
<p>
If you decide to create /etc/shorewall/common or /etc/shorewall/icmp.def, it
is a good idea to use the following technique (common file shown but the same
technique applies to icmpdef).</p>
<p>
/etc/shorewall/common:</p>
<blockquote>
<!--mstheme--></font><pre>source /etc/shorewall/common.def
&lt;add your rules here&gt;</pre><!--mstheme--><font face="arial, Arial, Helvetica">
</blockquote>
<p>If you need to supercede a rule in the released common.def file, you can add
the superceding rule before the 'source' command. Using this technique allows
you to add new rules while still getting the benefit of the latest common.def
file.</p>
<p>Remember that /etc/shorewall/common and /etc/shorewall/icmpdef define rules
that are only applied if the applicable policy is DROP or REJECT. These rules
are NOT applied if the policy is ACCEPT or CONTINUE.<br>
</p>
<p align="left"><font size="2">Last updated
8/5/2002 - <a href="support.htm">Tom
Eastep</a></font></p>
<p align="left"><a href="copyright.htm"><font size="2">Copyright 2002 Thomas M. Eastep</font></a></p>
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