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<h1 align="center"><font color="#ffffff">Starting/Stopping and Monitoring
the Firewall</font></h1>
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<p> If you have a permanent internet connection such as DSL or Cable,
I recommend that you start the firewall automatically at boot.
Once you have installed "firewall" in your init.d directory, simply
type "chkconfig --add firewall". This will start the firewall
in run levels 2-5 and stop it in run levels 1 and 6. If you want
to configure your firewall differently from this default, you can
use the "--level" option in chkconfig (see "man chkconfig") or using
your favorite graphical run-level editor.</p>
<p><strong><u> <font color="#000099"> Important Notes:</font></u></strong><br>
</p>
<ol>
<li>Shorewall startup is disabled by default. Once you
have configured your firewall, you can enable startup by removing the
file /etc/shorewall/startup_disabled. Note: Users of the .deb package
must edit /etc/default/shorewall and set 'startup=1'.<br>
</li>
<li>If you use dialup, you may want to start the firewall
in your /etc/ppp/ip-up.local script. I recommend just placing "shorewall
restart" in that script.</li>
</ol>
<p> </p>
<p> You can manually start and stop Shoreline Firewall using the "shorewall"
shell program. Please refer to the <a
href="file:///vfat/Shorewall-docs/starting_and_stopping_shorewall.htm#StateDiagram">Shorewall
State Diagram</a> is shown at the bottom of this page. </p>
<ul>
<li>shorewall start - starts the firewall</li>
<li>shorewall stop - stops the firewall; the only traffic
permitted through the firewall is from systems listed in /etc/shorewall/routestopped
(Beginning with version 1.4.7, if ADMINISABSENTMINDED=Yes in /etc/shorewall/shorewall.conf
then in addition, all existing connections are permitted and any new connections
originating from the firewall itself are allowed).</li>
<li>shorewall restart - stops the firewall (if it's
running) and then starts it again</li>
<li>shorewall reset - reset the packet and byte counters
in the firewall</li>
<li>shorewall clear - remove all rules and chains
installed by Shoreline Firewall. The firewall is "wide open"</li>
<li>shorewall refresh - refresh the rules involving
the broadcast addresses of firewall interfaces, <a
href="blacklisting_support.htm">the black list</a>, <a
href="traffic_shaping.htm">traffic control rules</a> and <a
href="ECN.html">ECN control rules</a>.</li>
</ul>
If you include the keyword <i>debug</i> as the first argument,
then a shell trace of the command is produced as in:<br>
<pre> <font color="#009900"><b>shorewall debug start 2> /tmp/trace</b></font><br></pre>
<p>The above command would trace the 'start' command and place the trace information
in the file /tmp/trace<br>
</p>
<p>Beginning with version 1.4.7, shorewall can give detailed help about each
of its commands:<br>
</p>
<ul>
<li>shorewall help [ <i>command</i> | host | address ]<br>
</li>
</ul>
<p>The "shorewall" program may also be used to monitor the firewall.</p>
<ul>
<li>shorewall status - produce a verbose report about
the firewall (iptables -L -n -v)</li>
<li>shorewall show <i>chain</i> - produce a verbose
report about <i>chain </i>(iptables -L <i>chain</i>
-n -v)</li>
<li>shorewall show nat - produce a verbose report about
the nat table (iptables -t nat -L -n -v)</li>
<li>shorewall show tos - produce a verbose report about
the mangle table (iptables -t mangle -L -n -v)</li>
<li>shorewall show log - display the last 20 packet
log entries.</li>
<li>shorewall show connections - displays the IP connections
currently being tracked by the firewall.</li>
<li>shorewall
show tc
- displays information about the traffic control/shaping configuration.</li>
<li>shorewall monitor [ delay ] - Continuously display
the firewall status, last 20 log entries and nat. When the
log entry display changes, an audible alarm is sounded.</li>
<li>shorewall hits - Produces several reports about
the Shorewall packet log messages in the current /var/log/messages
file.</li>
<li>shorewall version - Displays the installed
version number.</li>
<li>shorewall check - Performs a <u>cursory</u> validation of
the zones, interfaces, hosts, rules and policy files.<br>
<br>
<font size="4" color="#ff6666"><b>The "check" command is totally
unsuppored and does not parse and validate the generated iptables
commands. Even though the "check" command completes successfully,
the configuration may fail to start. Problem reports that complain about
errors that the 'check' command does not detect will not be accepted.<br>
<br>
See the recommended way to make configuration changes described
below.</b></font><br>
<br>
</li>
<li>shorewall try<i> configuration-directory</i> [<i>
timeout</i> ] - Restart shorewall using the specified configuration
and if an error occurs or if the<i> timeout </i> option is given
and the new configuration has been up for that many seconds then
shorewall is restarted using the standard configuration.</li>
<li>shorewall deny, shorewall reject, shorewall accept
and shorewall save implement <a
href="blacklisting_support.htm">dynamic blacklisting</a>.</li>
<li>shorewall logwatch (added in version 1.3.2) - Monitors
the <a href="#Conf">LOGFILE </a>and produces an audible alarm
when new Shorewall messages are logged.</li>
</ul>
Beginning with Shorewall 1.4.6, /sbin/shorewall supports a couple of
commands for dealing with IP addresses and IP address ranges:<br>
<ul>
<li>shorewall ipcalc [ <i>address mask </i>| <i>address/vlsm</i> ]
- displays the network address, broadcast address, network in CIDR notation
and netmask corresponding to the input[s].</li>
<li>shorewall iprange <i>address1-address2</i> - Decomposes the specified
range of IP addresses into the equivalent list of network/host addresses.
<br>
</li>
</ul>
There is a set of commands dealing with <a
href="blacklisting_support.htm">dynamic blacklisting</a>:<br>
<ul>
<li>shorewall drop <i><ip address list> </i>- causes packets from
the listed IP addresses to be silently dropped by the firewall.</li>
<li>shorewall reject <i><ip address list> </i>- causes packets from
the listed IP addresses to be rejected by the firewall.</li>
<li>shorewall allow <i><ip address list> </i>- re-enables receipt
of packets from hosts previously blacklisted by a <i>drop</i> or <i>reject</i>
command.</li>
<li>shorewall save - save the dynamic blacklisting configuration so that
it will be automatically restored the next time that the firewall is
restarted.</li>
<li>show dynamic - displays the dynamic blacklisting chain.<br>
</li>
</ul>
Finally, the "shorewall" program may be used to dynamically alter the
contents of a zone.<br>
<ul>
<li>shorewall add <i>interface</i>[:<i>host]</i> <i>zone
</i>- Adds the specified interface (and host if included) to the
specified zone.</li>
<li>shorewall delete <i>interface</i>[:<i>host]</i> <i>zone
</i>- Deletes the specified interface (and host if included) from
the specified zone.</li>
</ul>
<blockquote>Examples:<br>
<blockquote><font color="#009900"><b>shorewall add ipsec0:192.0.2.24 vpn1</b></font>
-- adds the address 192.0.2.24 from interface ipsec0 to the zone vpn1<br>
<font color="#009900"><b> shorewall delete ipsec0:192.0.2.24
vpn1</b></font> -- deletes the address 192.0.2.24 from interface ipsec0
from zone vpn1<br>
</blockquote>
</blockquote>
<p> The <b>shorewall start</b>, <b>shorewall restart, shorewall check, </b>and
<b>shorewall try </b>commands allow you to specify which <a
href="configuration_file_basics.htm#Configs"> Shorewall configuration</a>
to use:</p>
<blockquote>
<p> shorewall [ -c <i>configuration-directory</i> ] {start|restart|check}<br>
shorewall try <i>configuration-directory</i></p>
</blockquote>
<p> If a <i>configuration-directory</i> is specified, each time that Shorewall
is going to use a file in /etc/shorewall it will first look in the
<i>configuration-directory</i> . If the file is present in the <i>configuration-directory</i>,
that file will be used; otherwise, the file in /etc/shorewall will
be used.</p>
<p> When changing the configuration of a production firewall, I recommend
the following:</p>
<ul>
<li><font color="#009900"><b>mkdir /etc/test</b></font></li>
<li><font color="#009900"><b>cd /etc/test</b></font></li>
<li><copy any files that you need to change
from /etc/shorewall to . and change them here></li>
<li><font color="#009900"><b>shorewall -c . check</b></font></li>
<li><correct any errors found by check and check again></li>
<li><font
color="#009900"><b>/sbin/shorewall try .</b></font></li>
</ul>
<p> If the configuration starts but doesn't work, just "shorewall restart"
to restore the old configuration. If the new configuration fails
to start, the "try" command will automatically start the old one for
you.</p>
<p> When the new configuration works then just </p>
<ul>
<li><font color="#009900"><b>cp * /etc/shorewall</b></font></li>
<li><font color="#009900"><b>cd</b></font></li>
<li><font color="#009900"><b>rm -rf /etc/test</b></font></li>
</ul>
<p><a name="StateDiagram"></a>The Shorewall State Diargram is depicted below.<br>
</p>
<div align="center"><img src="images/State_Diagram.png"
alt="(State Diagram)" width="747" height="714" align="middle">
<br>
</div>
<p>� <br>
</p>
You will note that the commands that result in state transitions
use the word "firewall" rather than "shorewall". That is because the
actual transitions are done by /usr/share/shorewall/firewall; /sbin/shorewall
runs 'firewall" according to the following table:<br>
<br>
<table cellpadding="2" cellspacing="2" border="1">
<tbody>
<tr>
<td valign="top"><u><b>/sbin/shorewall Command</b><br>
</u></td>
<td valign="top"><u><b>Resulting /usr/share/shorewall/firewall Command</b><br>
</u></td>
<td valign="top"><u><b>Effect if the Command Succeeds</b><br>
</u></td>
</tr>
<tr>
<td valign="top">shorewall start<br>
</td>
<td valign="top">firewall start<br>
</td>
<td valign="top">The system filters packets based on your current
Shorewall Configuration<br>
</td>
</tr>
<tr>
<td valign="top">shorewall stop<br>
</td>
<td valign="top">firewall stop<br>
</td>
<td valign="top">Only traffic to/from hosts listed in /etc/shorewall/hosts
is passed to/from/through the firewall. For Shorewall versions beginning
with 1.4.7, if ADMINISABSENTMINDED=Yes in /etc/shorewall/shorewall.conf then
in addition, all existing connections are retained and all connection requests
from the firewall are accepted.<br>
</td>
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<td valign="top">shorewall restart<br>
</td>
<td valign="top">firewall restart<br>
</td>
<td valign="top">Logically equivalent to "firewall stop;firewall
start"<br>
</td>
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<tr>
<td valign="top">shorewall add<br>
</td>
<td valign="top">firewall add<br>
</td>
<td valign="top">Adds a host or subnet to a dynamic zone<br>
</td>
</tr>
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<td valign="top">shorewall delete<br>
</td>
<td valign="top">firewall delete<br>
</td>
<td valign="top">Deletes a host or subnet from a dynamic zone<br>
</td>
</tr>
<tr>
<td valign="top">shorewall refresh<br>
</td>
<td valign="top">firewall refresh<br>
</td>
<td valign="top">Reloads rules dealing with static blacklisting,
traffic control and ECN.<br>
</td>
</tr>
<tr>
<td valign="top">shorewall clear<br>
</td>
<td valign="top">firewall clear<br>
</td>
<td valign="top">Removes all Shorewall rules, chains, addresses,
routes and ARP entries.<br>
</td>
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<td valign="top">shorewall try<br>
</td>
<td valign="top">firewall -c <new configuration>
restart<br>
If unsuccessful then firewall start (standard configuration)<br>
If timeout then firewall restart (standard configuration)<br>
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<br>
<p><font size="2"> Updated 7/31/2003 - <a href="support.htm">Tom Eastep</a>
</font></p>
<p><font face="Trebuchet MS"><a href="copyright.htm"><font size="2">Copyright</font>
� <font size="2">2001, 2002, 2003 Thomas M. Eastep.</font></a></font><br>
</p>
<br>
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