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Convert ping.html to Docbook XML
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<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
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<html>
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<head>
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<title>ICMP Echo-request (Ping)</title>
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<meta http-equiv="content-type"
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content="text/html; charset=ISO-8859-1">
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<meta name="author" content="Tom Eastep">
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</head>
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<body>
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<br>
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<h1 style="text-align: center;">ICMP Echo-request (Ping)<br>
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</h1>
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Shorewall 'Ping' management has evolved over time with the latest
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change coming in Shorewall version 1.4.0. To find out which version of
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Shorewall you are running, at a shell prompt type "<font color="#009900"><b>/sbin/shorewall
|
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version</b></font>". If that command gives you an error, it's time to
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upgrade since you have a very old version of Shorewall installed (1.2.4
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or earlier).<br>
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<h2>Shorewall Versions >= 1.4.0</h2>
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In Shoreall 1.4.0 and later version, ICMP echo-request's are treated
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just like any other connection request.<br>
|
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<br>
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In order to accept ping requests from zone z1 to zone z2 where the
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policy for z1 to z2 is not ACCEPT, you need a rule in
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/etc/shoreall/rules of the form:<br>
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<blockquote>ACCEPT <i>z1
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z2 </i>icmp 8<br>
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</blockquote>
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Example: <br>
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<br>
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To permit ping from the local zone to the firewall:<br>
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<blockquote>ACCEPT loc
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fw icmp 8<br>
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</blockquote>
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If you would like to accept 'ping' by default even when the relevant
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policy is DROP or REJECT, create <b>/etc/shorewall/icmpdef </b>if it
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doesn't already exist and in that file place the following command:<br>
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<blockquote>
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<pre><b><font color="#009900">run_iptables -A icmpdef -p icmp --icmp-type 8 -j ACCEPT<br></font></b></pre>
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</blockquote>
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With that rule in place, if you want to ignore 'ping' from z1 to z2
|
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then you need a rule of the form:<br>
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<blockquote>DROP <i>z1
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z2 </i>icmp 8<br>
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</blockquote>
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Example:<br>
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<br>
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To drop ping from the internet, you would need this rule in
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/etc/shorewall/rules:<br>
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<br>
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<blockquote>DROP net
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fw icmp 8<br>
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</blockquote>
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<h2>Shorewall Versions >= 1.3.14 and < 1.4.0 with
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OLD_PING_HANDLING=No in /etc/shorewall/shorewall.conf</h2>
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In 1.3.14, Ping handling was put under control of the rules and
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policies just like any other connection request. In order to accept
|
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ping requests from zone z1 to zone z2 where the policy for z1 to z2 is
|
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not ACCEPT, you need a rule in /etc/shoreall/rules of the form:<br>
|
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<blockquote>ACCEPT <i>z1
|
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z2 </i>icmp 8<br>
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</blockquote>
|
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Example: <br>
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<br>
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To permit ping from the local zone to the firewall:<br>
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<blockquote>ACCEPT loc
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fw icmp 8<br>
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</blockquote>
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If you would like to accept 'ping' by default even when the relevant
|
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policy is DROP or REJECT, create <b>/etc/shorewall/icmpdef </b>if it
|
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doesn't already exist and in that file place the following command:<br>
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<blockquote>
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<pre><b><font color="#009900">run_iptables -A icmpdef -p icmp --icmp-type 8 -j ACCEPT<br></font></b></pre>
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</blockquote>
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With that rule in place, if you want to ignore 'ping' from z1 to z2
|
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then you need a rule of the form:<br>
|
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<blockquote>DROP <i>z1
|
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z2 </i>icmp 8<br>
|
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</blockquote>
|
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Example:<br>
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<br>
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To drop ping from the internet, you would need this rule in
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/etc/shorewall/rules:<br>
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<blockquote>DROP net
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fw icmp 8<br>
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</blockquote>
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<span style="font-weight: bold;">NOTE: </span>There is one
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exception to the above description. In 1.3.14 and 1.3.14a, ping from
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the firewall itself is enabled unconditionally. This suprising
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"feature" was removed in version 1.4.0.<br>
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<blockquote> </blockquote>
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<blockquote> </blockquote>
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<h2>Shorewall Versions < 1.3.14 or with OLD_PING_HANDLING=Yes in
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/etc/shorewall/shorewall.conf<br>
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</h2>
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There are several aspects to the old Shorewall Ping management:<br>
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<ol>
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<li>The <b>noping</b> and <b>filterping </b>interface options in <a
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href="Documentation.htm#Interfaces">/etc/shorewall/interfaces</a>.</li>
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<li>The <b>FORWARDPING</b> option in<a href="Documentation.htm#Conf">
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/etc/shorewall/shorewall.conf</a>.</li>
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<li>Explicit rules in <a href="Documentation.htm#Rules">/etc/shorewall/rules</a>.</li>
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</ol>
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There are two cases to consider:<br>
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<ol>
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<li>Ping requests addressed to the firewall itself; and</li>
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<li>Ping requests being forwarded to another system. Included here
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are all cases of packet forwarding including NAT, DNAT rule, Proxy ARP
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and simple routing.</li>
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</ol>
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These cases will be covered separately.<br>
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<h3>Ping Requests Addressed to the Firewall Itself</h3>
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For ping requests addressed to the firewall, the sequence is as follows:<br>
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<ol>
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<li>If neither <b>noping</b> nor <b>filterping </b>are specified
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for the interface that receives the ping request then the request will
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be responded to with an ICMP echo-reply.</li>
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<li>If <b>noping</b> is specified for the interface that receives
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the ping request then the request is ignored.</li>
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<li>If <b>filterping </b>is specified for the interface then the
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request is passed to the rules/policy evaluation.</li>
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</ol>
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<h3>Ping Requests Forwarded by the Firewall</h3>
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These requests are <b>always</b> passed to rules/policy evaluation.<br>
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<h3>Rules Evaluation</h3>
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Ping requests are ICMP type 8. So the general rule format is:<br>
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<br>
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<i>Target
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Source Destination </i>icmp
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8<br>
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<br>
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Example 1. Accept pings from the net to the dmz (pings are responded to
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with an ICMP echo-reply):<br>
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<br>
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ACCEPT net
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dmz icmp 8<br>
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<br>
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Example 2. Drop pings from the net to the firewall<br>
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<br>
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DROP net
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fw icmp 8<br>
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<h3>Policy Evaluation</h3>
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If no applicable rule is found, then the policy for the source to
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the destination is applied.<br>
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<ol>
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<li>If the relevant policy is ACCEPT then the request is responded to
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with an ICMP echo-reply.</li>
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<li>If <b>FORWARDPING</b> is set to Yes in
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/etc/shorewall/shorewall.conf then the request is responded to with an
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ICMP echo-reply.</li>
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<li>Otherwise, the relevant REJECT or DROP policy is used and the
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request is either rejected or simply ignored.</li>
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</ol>
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<div style="text-align: justify;"><font size="2">Updated 8/23/2003 - <a
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href="support.htm">Tom Eastep</a></font></div>
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<p><font size="2"> </font></p>
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<p><a href="copyright.htm"><font size="2">Copyright</font> © <font
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size="2">2001, 2002, 2003 Thomas M. Eastep.</font></a><br>
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</p>
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<br>
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</body>
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</html>
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681
Shorewall-docs/ping.xml
Normal file
681
Shorewall-docs/ping.xml
Normal file
@ -0,0 +1,681 @@
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<?xml version="1.0" encoding="UTF-8"?>
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<!DOCTYPE article PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
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||||
"http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
|
||||
<article>
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||||
<!--$Id$-->
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|
||||
<articleinfo>
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||||
<title>ICMP Echo-request (Ping)</title>
|
||||
|
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<authorgroup>
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<author>
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<firstname>Tom</firstname>
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<surname>Eastep</surname>
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</author>
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</authorgroup>
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<pubdate>2003-08-23</pubdate>
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<copyright>
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<year>2001-2003</year>
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<holder>Thomas M. Eastep</holder>
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</copyright>
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|
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<legalnotice>
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<para>Permission is granted to copy, distribute and/or modify this
|
||||
document under the terms of the GNU Free Documentation License, Version
|
||||
1.2 or any later version published by the Free Software Foundation; with
|
||||
no Invariant Sections, with no Front-Cover, and with no Back-Cover
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||||
Texts. A copy of the license is included in the section entitled
|
||||
<quote><ulink url="GnuCopyright.htm">GNU Free Documentation License</ulink></quote>.</para>
|
||||
</legalnotice>
|
||||
</articleinfo>
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|
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<note>
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<para>Shorewall 'Ping' management has evolved over time with the
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latest change coming in Shorewall version 1.4.0. To find out which version
|
||||
of Shorewall you are running, at a shell prompt type "/sbin/shorewall
|
||||
version". If that command gives you an error, it's time to upgrade
|
||||
since you have a very old version of Shorewall installed (1.2.4 or
|
||||
earlier).</para>
|
||||
</note>
|
||||
|
||||
<section>
|
||||
<title>Shorewall Versions >= 1.4.0</title>
|
||||
|
||||
<para>In Shoreall 1.4.0 and later version, ICMP echo-request's are
|
||||
treated just like any other connection request.</para>
|
||||
|
||||
<para>In order to accept ping requests from zone z1 to zone z2 where the
|
||||
policy for z1 to z2 is not ACCEPT, you need a rule in /etc/shoreall/rules
|
||||
of the form:</para>
|
||||
|
||||
<informaltable>
|
||||
<tgroup cols="7">
|
||||
<thead>
|
||||
<row>
|
||||
<entry align="center">ACTION</entry>
|
||||
|
||||
<entry align="center">SOURCE</entry>
|
||||
|
||||
<entry align="center">DESTINATION</entry>
|
||||
|
||||
<entry align="center">PROTOCOL</entry>
|
||||
|
||||
<entry align="center">PORT(S)</entry>
|
||||
|
||||
<entry align="center">SOURCE PORT(S)</entry>
|
||||
|
||||
<entry align="center">ORIGINAL DEST</entry>
|
||||
</row>
|
||||
</thead>
|
||||
|
||||
<tbody>
|
||||
<row>
|
||||
<entry>ACCEPT</entry>
|
||||
|
||||
<entry>z1</entry>
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||||
|
||||
<entry>z2</entry>
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||||
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||||
<entry>icmp</entry>
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||||
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||||
<entry>8</entry>
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||||
|
||||
<entry></entry>
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||||
|
||||
<entry></entry>
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||||
</row>
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||||
</tbody>
|
||||
</tgroup>
|
||||
</informaltable>
|
||||
|
||||
<example>
|
||||
<title>Ping from local zone to firewall</title>
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|
||||
<para>To permit ping from the local zone to the firewall:</para>
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|
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<informaltable>
|
||||
<tgroup cols="7">
|
||||
<thead>
|
||||
<row>
|
||||
<entry align="center">ACTION</entry>
|
||||
|
||||
<entry align="center">SOURCE</entry>
|
||||
|
||||
<entry align="center">DESTINATION</entry>
|
||||
|
||||
<entry align="center">PROTOCOL</entry>
|
||||
|
||||
<entry align="center">PORT(S)</entry>
|
||||
|
||||
<entry align="center">SOURCE PORT(S)</entry>
|
||||
|
||||
<entry align="center">ORIGINAL DEST</entry>
|
||||
</row>
|
||||
</thead>
|
||||
|
||||
<tbody>
|
||||
<row>
|
||||
<entry>ACCEPT</entry>
|
||||
|
||||
<entry>loc</entry>
|
||||
|
||||
<entry>fw</entry>
|
||||
|
||||
<entry>icmp</entry>
|
||||
|
||||
<entry>8</entry>
|
||||
|
||||
<entry></entry>
|
||||
|
||||
<entry></entry>
|
||||
</row>
|
||||
</tbody>
|
||||
</tgroup>
|
||||
</informaltable>
|
||||
</example>
|
||||
|
||||
<para>If you would like to accept 'ping' by default even when the
|
||||
relevant policy is DROP or REJECT, create /etc/shorewall/icmpdef if it
|
||||
doesn't already exist and in that file place the following command:</para>
|
||||
|
||||
<programlisting> run_iptables -A icmpdef -p icmp --icmp-type 8 -j ACCEPT</programlisting>
|
||||
|
||||
<para>With that rule in place, if you want to ignore 'ping' from
|
||||
z1 to z2 then you need a rule of the form:</para>
|
||||
|
||||
<informaltable>
|
||||
<tgroup cols="7">
|
||||
<thead>
|
||||
<row>
|
||||
<entry align="center">ACTION</entry>
|
||||
|
||||
<entry align="center">SOURCE</entry>
|
||||
|
||||
<entry align="center">DESTINATION</entry>
|
||||
|
||||
<entry align="center">PROTOCOL</entry>
|
||||
|
||||
<entry align="center">PORT(S)</entry>
|
||||
|
||||
<entry align="center">SOURCE PORT(S)</entry>
|
||||
|
||||
<entry align="center">ORIGINAL DEST</entry>
|
||||
</row>
|
||||
</thead>
|
||||
|
||||
<tbody>
|
||||
<row>
|
||||
<entry>DROP</entry>
|
||||
|
||||
<entry>z1</entry>
|
||||
|
||||
<entry>z2</entry>
|
||||
|
||||
<entry>icmp</entry>
|
||||
|
||||
<entry>8</entry>
|
||||
|
||||
<entry></entry>
|
||||
|
||||
<entry></entry>
|
||||
</row>
|
||||
</tbody>
|
||||
</tgroup>
|
||||
</informaltable>
|
||||
|
||||
<example>
|
||||
<title>Silently drop pings from the Internet</title>
|
||||
|
||||
<para>To drop ping from the internet, you would need this rule in
|
||||
/etc/shorewall/rules:</para>
|
||||
|
||||
<informaltable>
|
||||
<tgroup cols="7">
|
||||
<thead>
|
||||
<row>
|
||||
<entry align="center">ACTION</entry>
|
||||
|
||||
<entry align="center">SOURCE</entry>
|
||||
|
||||
<entry align="center">DESTINATION</entry>
|
||||
|
||||
<entry align="center">PROTOCOL</entry>
|
||||
|
||||
<entry align="center">PORT(S)</entry>
|
||||
|
||||
<entry align="center">SOURCE PORT(S)</entry>
|
||||
|
||||
<entry align="center">ORIGINAL DEST</entry>
|
||||
</row>
|
||||
</thead>
|
||||
|
||||
<tbody>
|
||||
<row>
|
||||
<entry>DROP</entry>
|
||||
|
||||
<entry>net</entry>
|
||||
|
||||
<entry>fw</entry>
|
||||
|
||||
<entry>icmp</entry>
|
||||
|
||||
<entry>8</entry>
|
||||
|
||||
<entry></entry>
|
||||
|
||||
<entry></entry>
|
||||
</row>
|
||||
</tbody>
|
||||
</tgroup>
|
||||
</informaltable>
|
||||
</example>
|
||||
|
||||
<para>Note that the above rule may be used without any additions to
|
||||
/etc/shorewall/icmpdef to prevent your log from being flooded by messages
|
||||
generated from remote pinging.</para>
|
||||
</section>
|
||||
|
||||
<section>
|
||||
<title>Shorewall Versions >= 1.3.14 and < 1.4.0 with
|
||||
OLD_PING_HANDLING=No in /etc/shorewall/shorewall.conf</title>
|
||||
|
||||
<para>In 1.3.14, Ping handling was put under control of the rules and
|
||||
policies just like any other connection request. In order to accept ping
|
||||
requests from zone z1 to zone z2 where the policy for z1 to z2 is not
|
||||
ACCEPT, you need a rule in /etc/shoreall/rules of the form:</para>
|
||||
|
||||
<informaltable>
|
||||
<tgroup cols="7">
|
||||
<thead>
|
||||
<row>
|
||||
<entry align="center">ACTION</entry>
|
||||
|
||||
<entry align="center">SOURCE</entry>
|
||||
|
||||
<entry align="center">DESTINATION</entry>
|
||||
|
||||
<entry align="center">PROTOCOL</entry>
|
||||
|
||||
<entry align="center">PORT(S)</entry>
|
||||
|
||||
<entry align="center">SOURCE PORT(S)</entry>
|
||||
|
||||
<entry align="center">ORIGINAL DEST</entry>
|
||||
</row>
|
||||
</thead>
|
||||
|
||||
<tbody>
|
||||
<row>
|
||||
<entry>ACCEPT</entry>
|
||||
|
||||
<entry>z1</entry>
|
||||
|
||||
<entry>z2</entry>
|
||||
|
||||
<entry>icmp</entry>
|
||||
|
||||
<entry>8</entry>
|
||||
|
||||
<entry></entry>
|
||||
|
||||
<entry></entry>
|
||||
</row>
|
||||
</tbody>
|
||||
</tgroup>
|
||||
</informaltable>
|
||||
|
||||
<example>
|
||||
<title>Ping from local zone to firewall</title>
|
||||
|
||||
<para>To permit ping from the local zone to the firewall:</para>
|
||||
|
||||
<informaltable>
|
||||
<tgroup cols="7">
|
||||
<thead>
|
||||
<row>
|
||||
<entry align="center">ACTION</entry>
|
||||
|
||||
<entry align="center">SOURCE</entry>
|
||||
|
||||
<entry align="center">DESTINATION</entry>
|
||||
|
||||
<entry align="center">PROTOCOL</entry>
|
||||
|
||||
<entry align="center">PORT(S)</entry>
|
||||
|
||||
<entry align="center">SOURCE PORT(S)</entry>
|
||||
|
||||
<entry align="center">ORIGINAL DEST</entry>
|
||||
</row>
|
||||
</thead>
|
||||
|
||||
<tbody>
|
||||
<row>
|
||||
<entry>ACCEPT</entry>
|
||||
|
||||
<entry>loc</entry>
|
||||
|
||||
<entry>fw</entry>
|
||||
|
||||
<entry>icmp</entry>
|
||||
|
||||
<entry>8</entry>
|
||||
|
||||
<entry></entry>
|
||||
|
||||
<entry></entry>
|
||||
</row>
|
||||
</tbody>
|
||||
</tgroup>
|
||||
</informaltable>
|
||||
</example>
|
||||
|
||||
<para>If you would like to accept 'ping' by default even when the
|
||||
relevant policy is DROP or REJECT, create /etc/shorewall/icmpdef if it
|
||||
doesn't already exist and in that file place the following command:</para>
|
||||
|
||||
<programlisting> run_iptables -A icmpdef -p icmp --icmp-type 8 -j ACCEPT</programlisting>
|
||||
|
||||
<para>With that rule in place, if you want to ignore 'ping' from
|
||||
z1 to z2 then you need a rule of the form:</para>
|
||||
|
||||
<informaltable>
|
||||
<tgroup cols="7">
|
||||
<thead>
|
||||
<row>
|
||||
<entry align="center">ACTION</entry>
|
||||
|
||||
<entry align="center">SOURCE</entry>
|
||||
|
||||
<entry align="center">DESTINATION</entry>
|
||||
|
||||
<entry align="center">PROTOCOL</entry>
|
||||
|
||||
<entry align="center">PORT(S)</entry>
|
||||
|
||||
<entry align="center">SOURCE PORT(S)</entry>
|
||||
|
||||
<entry align="center">ORIGINAL DEST</entry>
|
||||
</row>
|
||||
</thead>
|
||||
|
||||
<tbody>
|
||||
<row>
|
||||
<entry>DROP</entry>
|
||||
|
||||
<entry>z1</entry>
|
||||
|
||||
<entry>z2</entry>
|
||||
|
||||
<entry>icmp</entry>
|
||||
|
||||
<entry>8</entry>
|
||||
|
||||
<entry></entry>
|
||||
|
||||
<entry></entry>
|
||||
</row>
|
||||
</tbody>
|
||||
</tgroup>
|
||||
</informaltable>
|
||||
|
||||
<example>
|
||||
<title>Silently drop pings from the Internet</title>
|
||||
|
||||
<para>To drop ping from the internet, you would need this rule in
|
||||
/etc/shorewall/rules:</para>
|
||||
|
||||
<informaltable>
|
||||
<tgroup cols="7">
|
||||
<thead>
|
||||
<row>
|
||||
<entry align="center">ACTION</entry>
|
||||
|
||||
<entry align="center">SOURCE</entry>
|
||||
|
||||
<entry align="center">DESTINATION</entry>
|
||||
|
||||
<entry align="center">PROTOCOL</entry>
|
||||
|
||||
<entry align="center">PORT(S)</entry>
|
||||
|
||||
<entry align="center">SOURCE PORT(S)</entry>
|
||||
|
||||
<entry align="center">ORIGINAL DEST</entry>
|
||||
</row>
|
||||
</thead>
|
||||
|
||||
<tbody>
|
||||
<row>
|
||||
<entry>DROP</entry>
|
||||
|
||||
<entry>net</entry>
|
||||
|
||||
<entry>fw</entry>
|
||||
|
||||
<entry>icmp</entry>
|
||||
|
||||
<entry>8</entry>
|
||||
|
||||
<entry></entry>
|
||||
|
||||
<entry></entry>
|
||||
</row>
|
||||
</tbody>
|
||||
</tgroup>
|
||||
</informaltable>
|
||||
</example>
|
||||
|
||||
<para>The above rule may be used without any additions to
|
||||
/etc/shorewall/icmpdef to prevent your log from being flooded by messages
|
||||
generated from remote pinging.</para>
|
||||
|
||||
<note>
|
||||
<para>There is one exception to the above description. In 1.3.14 and
|
||||
1.3.14a, ping from the firewall itself is enabled unconditionally. This
|
||||
suprising "feature" was removed in version 1.4.0.</para>
|
||||
</note>
|
||||
</section>
|
||||
|
||||
<section>
|
||||
<title>Shorewall Versions < 1.3.14 or with OLD_PING_HANDLING=Yes in
|
||||
/etc/shorewall/shorewall.conf</title>
|
||||
|
||||
<para>There are several aspects to the old Shorewall Ping management:</para>
|
||||
|
||||
<orderedlist>
|
||||
<listitem>
|
||||
<para>The <emphasis role="bold">noping</emphasis> and <emphasis
|
||||
role="bold">filterping</emphasis> interface options in <ulink
|
||||
url="Documentation.htm#Interfaces">/etc/shorewall/interfaces</ulink>.</para>
|
||||
</listitem>
|
||||
|
||||
<listitem>
|
||||
<para>The <emphasis role="bold">FORWARDPING</emphasis> option in
|
||||
<ulink url="Documentation.htm#Config">/etc/shorewall/shorewall.conf</ulink>.</para>
|
||||
</listitem>
|
||||
|
||||
<listitem>
|
||||
<para>Explicit rules in <ulink url="Documentation.htm#rules">/etc/shorewall/rules</ulink>.</para>
|
||||
</listitem>
|
||||
</orderedlist>
|
||||
|
||||
<para>There are two cases to consider:</para>
|
||||
|
||||
<orderedlist>
|
||||
<listitem>
|
||||
<para>Ping requests addressed to the firewall itself; and</para>
|
||||
</listitem>
|
||||
|
||||
<listitem>
|
||||
<para>Ping requests being forwarded to another system. Included here
|
||||
are all cases of packet forwarding including NAT, DNAT rule, Proxy ARP
|
||||
and simple routing.</para>
|
||||
</listitem>
|
||||
</orderedlist>
|
||||
|
||||
<para>These cases will be covered separately.</para>
|
||||
|
||||
<section>
|
||||
<title>Ping Requests Addressed to the Firewall Itself</title>
|
||||
|
||||
<para>For ping requests addressed to the firewall, the sequence is as
|
||||
follows:</para>
|
||||
|
||||
<orderedlist>
|
||||
<listitem>
|
||||
<para>If neither <emphasis role="bold">noping</emphasis> nor
|
||||
<emphasis role="bold">filterping</emphasis> are specified for the
|
||||
interface that receives the ping request then the request will be
|
||||
responded to with an ICMP echo-reply.</para>
|
||||
</listitem>
|
||||
|
||||
<listitem>
|
||||
<para>If <emphasis role="bold">noping</emphasis> is specified for
|
||||
the interface that receives the ping request then the request is
|
||||
ignored.</para>
|
||||
</listitem>
|
||||
|
||||
<listitem>
|
||||
<para>If <emphasis role="bold">filterping</emphasis> is specified
|
||||
for the interface then the request is passed to the rules/policy
|
||||
evaluation.</para>
|
||||
</listitem>
|
||||
</orderedlist>
|
||||
</section>
|
||||
|
||||
<section>
|
||||
<title>Ping Requests Forwarded by the Firewall</title>
|
||||
|
||||
<para>These requests are always passed to rules/policy evaluation.</para>
|
||||
|
||||
<section>
|
||||
<title>Rules Evaluation</title>
|
||||
|
||||
<para>Ping requests are ICMP type 8. So the general rule format is:</para>
|
||||
|
||||
<informaltable>
|
||||
<tgroup cols="7">
|
||||
<thead>
|
||||
<row>
|
||||
<entry align="center">ACTION</entry>
|
||||
|
||||
<entry align="center">SOURCE</entry>
|
||||
|
||||
<entry align="center">DESTINATION</entry>
|
||||
|
||||
<entry align="center">PROTOCOL</entry>
|
||||
|
||||
<entry align="center">PORT(S)</entry>
|
||||
|
||||
<entry align="center">SOURCE PORT(S)</entry>
|
||||
|
||||
<entry align="center">ORIGINAL DEST</entry>
|
||||
</row>
|
||||
</thead>
|
||||
|
||||
<tbody>
|
||||
<row>
|
||||
<entry><<emphasis>action</emphasis>></entry>
|
||||
|
||||
<entry><<emphasis>source</emphasis>></entry>
|
||||
|
||||
<entry><<emphasis>destination</emphasis>></entry>
|
||||
|
||||
<entry>icmp</entry>
|
||||
|
||||
<entry>8</entry>
|
||||
|
||||
<entry></entry>
|
||||
|
||||
<entry></entry>
|
||||
</row>
|
||||
</tbody>
|
||||
</tgroup>
|
||||
</informaltable>
|
||||
|
||||
<example>
|
||||
<title>Allow ping from DMZ to Net</title>
|
||||
|
||||
<para>Example 1. Accept pings from the net to the dmz (pings are
|
||||
responded to with an ICMP echo-reply):</para>
|
||||
|
||||
<informaltable>
|
||||
<tgroup cols="7">
|
||||
<thead>
|
||||
<row>
|
||||
<entry align="center">ACTION</entry>
|
||||
|
||||
<entry align="center">SOURCE</entry>
|
||||
|
||||
<entry align="center">DESTINATION</entry>
|
||||
|
||||
<entry align="center">PROTOCOL</entry>
|
||||
|
||||
<entry align="center">PORT(S)</entry>
|
||||
|
||||
<entry align="center">SOURCE PORT(S)</entry>
|
||||
|
||||
<entry align="center">ORIGINAL DEST</entry>
|
||||
</row>
|
||||
</thead>
|
||||
|
||||
<tbody>
|
||||
<row>
|
||||
<entry>ACCEPT</entry>
|
||||
|
||||
<entry>dmz</entry>
|
||||
|
||||
<entry>net</entry>
|
||||
|
||||
<entry>icmp</entry>
|
||||
|
||||
<entry>8</entry>
|
||||
|
||||
<entry></entry>
|
||||
|
||||
<entry></entry>
|
||||
</row>
|
||||
</tbody>
|
||||
</tgroup>
|
||||
</informaltable>
|
||||
</example>
|
||||
|
||||
<example>
|
||||
<title>Silently drop pings from the Net</title>
|
||||
|
||||
<para>Drop pings from the net to the firewall:</para>
|
||||
|
||||
<informaltable>
|
||||
<tgroup cols="7">
|
||||
<thead>
|
||||
<row>
|
||||
<entry align="center">ACTION</entry>
|
||||
|
||||
<entry align="center">SOURCE</entry>
|
||||
|
||||
<entry align="center">DESTINATION</entry>
|
||||
|
||||
<entry align="center">PROTOCOL</entry>
|
||||
|
||||
<entry align="center">PORT(S)</entry>
|
||||
|
||||
<entry align="center">SOURCE PORT(S)</entry>
|
||||
|
||||
<entry align="center">ORIGINAL DEST</entry>
|
||||
</row>
|
||||
</thead>
|
||||
|
||||
<tbody>
|
||||
<row>
|
||||
<entry>DROP</entry>
|
||||
|
||||
<entry>net</entry>
|
||||
|
||||
<entry>fw</entry>
|
||||
|
||||
<entry>icmp</entry>
|
||||
|
||||
<entry>8</entry>
|
||||
|
||||
<entry></entry>
|
||||
|
||||
<entry></entry>
|
||||
</row>
|
||||
</tbody>
|
||||
</tgroup>
|
||||
</informaltable>
|
||||
</example>
|
||||
</section>
|
||||
|
||||
<section>
|
||||
<title>Policy Evaluation</title>
|
||||
|
||||
<para>If no applicable rule is found, then the policy for the source
|
||||
to the destination is applied.</para>
|
||||
|
||||
<orderedlist>
|
||||
<listitem>
|
||||
<para>If the relevant policy is ACCEPT then the request is
|
||||
responded to with an ICMP echo-reply.</para>
|
||||
</listitem>
|
||||
|
||||
<listitem>
|
||||
<para>If <emphasis role="bold">FORWARDPING</emphasis> is set to
|
||||
Yes in /etc/shorewall/shorewall.conf then the request is responded
|
||||
to with an ICMP echo-reply.</para>
|
||||
</listitem>
|
||||
|
||||
<listitem>
|
||||
<para>Otherwise, the relevant REJECT or DROP policy is used and
|
||||
the request is either rejected or simply ignored.</para>
|
||||
</listitem>
|
||||
</orderedlist>
|
||||
</section>
|
||||
</section>
|
||||
</section>
|
||||
</article>
|
||||
Loading…
Reference in New Issue
Block a user