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git-svn-id: https://shorewall.svn.sourceforge.net/svnroot/shorewall/trunk@240 fbd18981-670d-0410-9b5c-8dc0c1a9a2bb
2863 lines
144 KiB
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2863 lines
144 KiB
HTML
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<meta name="GENERATOR" content="Microsoft FrontPage 5.0">
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<title>Shorewall 1.3 Documentation</title>
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<table border="0" cellpadding="0" cellspacing="0"
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style="border-collapse: collapse;" width="100%" id="AutoNumber4"
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bgcolor="#400169" height="90">
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<tbody>
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<tr>
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<td width="100%">
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<h1 align="center"><font color="#ffffff">Shorewall 1.3 Reference</font></h1>
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</td>
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</tr>
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</tbody>
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</table>
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<h2 align="center">This documentation is intended primarily for reference.
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Step-by-step instructions for configuring Shorewall in common setups
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may be found in the <a href="shorewall_quickstart_guide.htm">QuickStart
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Guides</a>.</h2>
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<h2>Components</h2>
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<p>Shorewall consists of the following components: </p>
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<ul>
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<li><b><a href="#Variables">params</a></b> -- a parameter file installed
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in /etc/shorewall that can be used to establish the values of shell variables
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for use in other files.</li>
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<li><b> <a href="#Conf">shorewall.conf</a></b> -- a parameter file
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installed in /etc/shorewall that is used to set several firewall
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parameters.</li>
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<li><b> <a href="#Zones">zones</a></b> - a parameter file installed
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in /etc/shorewall that defines a network partitioning into "zones"</li>
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<li><b> <a href="#Policy">policy</a></b> -- a parameter file installed
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in /etc/shorewall/ that establishes overall firewall policy.</li>
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<li><b> <a href="#Rules">rules</a> </b> -- a parameter file installed
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in /etc/shorewall and used to express firewall rules that are exceptions
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to the high-level policies established in /etc/shorewall/policy.</li>
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<li><b><a href="#Blacklist">blacklist</a> -- </b>a parameter file installed
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in /etc/shorewall and used to list blacklisted IP/subnet/MAC addresses.</li>
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<li><b> functions</b> -- a set of shell functions used by both the
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firewall and shorewall shell programs. Installed in /etc/shorewall prior
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to version 1.3.2 and in /var/lib/shorewall in later versions.</li>
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<li><b> <a href="#modules">modules</a></b> -- a parameter file installed
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||
in /etc/shorewall and that specifies kernel modules and their parameters.
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Shorewall will automatically load the modules specified in this file.</li>
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<li><a href="#TOS"><b> tos</b> </a>-- a parameter file installed in
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/etc/shorewall that is used to specify how the Type of Service (TOS)
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field in packets is to be set.</li>
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<li><a href="#Scripts"><b> icmp.def</b> </a>-- a parameter file installed
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||
in /etc/shorewall and that specifies the default handling of ICMP
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packets when the applicable policy is DROP or REJECT.</li>
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<li><b><a href="#Scripts">common.def</a></b> -- a parameter file installed
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in in /etc/shorewall that defines firewall-wide rules that are applied
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before a DROP or REJECT policy is applied.</li>
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<li><b> <a href="#Interfaces">interfaces</a> </b> -- a parameter
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file installed in /etc/shorewall/ and used to describe the interfaces
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on the firewall system.</li>
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<li><a href="#Hosts"><b> hosts</b> </a>-- a parameter file installed
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in /etc/shorewall/ and used to describe individual hosts or subnetworks
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in zones.</li>
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<li><b> <a href="#Masq">masq</a></b> - This file also describes
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IP masquerading under Shorewall and is installed in /etc/shorewall.</li>
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<li><b><a href="#Structure">firewall</a></b> -- a shell program that
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||
reads the configuration files in /etc/shorewall and configures your
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firewall. This file is installed in your init.d
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directory (/etc/rc.d/init.d ) where it is renamed <i>shorewall.</i><EFBFBD>
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/etc/shorewall/firewall (/var/lib/shorewall/firewall in version 1.3.2 and
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later) is a symbolic link to this program.</li>
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<li><b> <a href="#NAT">nat</a></b> -- a parameter file in /etc/shorewall
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used to define <a href="#NAT"> static NAT</a> .</li>
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<li><b> <a href="#ProxyArp">proxyarp</a></b> -- a parameter file
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in /etc/shorewall used to define <a href="#ProxyArp"> Proxy Arp</a>
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.</li>
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<li><b><a href="#rfc1918">rfc1918</a></b> -- a parameter file in
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/etc/shorewall used to define the treatment of packets under the <a
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href="#Interfaces">norfc1918 interface option</a>.</li>
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<li><b><a href="#Routestopped">routestopped</a></b> -- a parameter file
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in /etc/shorewall used to define those hosts that can access the firewall
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when Shorewall is stopped.</li>
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<li><a href="traffic_shaping.htm#tcrules"><b>tcrules</b> </a>-- a parameter
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file in /etc/shorewall used to define rules for classifying packets for
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<a href="traffic_shaping.htm">Traffic Shaping/Control</a>.</li>
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<li><b> <a href="#Tunnels">tunnels</a></b> -- a parameter file in
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/etc/shorewall used to define IPSec tunnels.</li>
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<li><b> <a href="#Starting">shorewall</a> </b> -- a shell program
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||
(requiring a Bourne shell or derivative) used to control and
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monitor the firewall. This should be placed in /sbin or in
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/usr/sbin (the install.sh script and the rpm install this file
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in /sbin).</li>
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<li><b> <a href="#Version">version</a></b> -- a file created in /etc/shorewall/
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(/var/lib/shorewall in version 1.3.2 and later) that describes
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the version of<6F> Shorewall installed on your system.</li>
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</ul>
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<h2><a name="Variables"></a> /etc/shorewall/params</h2>
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<p>You may use the file /etc/shorewall/params file to set shell variables
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that you can then use in some of the other configuration files.</p>
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<p>It is suggested that variable names begin with an upper case letter<font
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size="1"> </font>to distinguish them from variables used internally
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within the Shorewall programs</p>
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<p>Example:</p>
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<pre><font face="Courier"> NET_IF=eth0<br> NET_BCAST=130.252.100.255<br> NET_OPTIONS=noping,norfc1918</font></pre>
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<p>Example (/etc/shorewall/interfaces record):</p>
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<pre> <font face="Courier">net $NET_IF $NET_BCAST $NET_OPTIONS</font></pre>
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<p>The result will be the same as if the record had been written</p>
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<pre> <font face="Courier">net eth0 130.252.100.255 noping,norfc1918</font></pre>
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<p>Variables may be used anywhere in the other configuration
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files.</p>
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<h2><b><a name="Zones"></a> </b>/etc/shorewall/zones</h2>
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<p>This file is used to define the network zones. There is one entry
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in /etc/shorewall/zones for each zone; Columns in an entry are:</p>
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<ul>
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<li><b> ZONE</b> - short name for the zone. The name should be 5 characters
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or less in length and consist of lower-case letters or numbers. Short
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names must begin with a letter and the name assigned to the firewall is
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reserved for use by Shorewall itself. Note that the output produced
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by iptables is much easier to read if you select short names that
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are three characters or less in length. The name "all" may not be
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used as a zone name nor may the zone name assigned to the firewall itself
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via the FW variable in <a href="#Conf">/etc/shorewall/shorewall.conf</a>.</li>
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<li><b> DISPLAY</b> - The name of the zone as displayed during Shorewall
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startup.</li>
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<li><b> COMMENTS</b> - Any comments that you want to make about the
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zone. Shorewall ignores these comments.</li>
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</ul>
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<p>The /etc/shorewall/zones file released with Shorewall is as follows:</p>
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<table border="1" style="border-collapse: collapse;" cellpadding="2">
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<tbody>
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<tr>
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<td><b> ZONE</b></td>
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<td><b> DISPLAY</b></td>
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<td><b> COMMENTS</b></td>
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</tr>
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<tr>
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<td>net</td>
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<td>Net</td>
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<td>Internet</td>
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</tr>
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<tr>
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<td>loc</td>
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<td>Local</td>
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<td>Local networks</td>
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</tr>
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<tr>
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<td>dmz</td>
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<td>DMZ</td>
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<td>Demilitarized zone</td>
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</tr>
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</tbody>
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</table>
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<p>You may add, delete and modify entries in the /etc/shorewall/zones file
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as desired so long as you have at least one zone defined.</p>
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<p><b><font size="5" color="#ff0000"> Warning 1: </font><font
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color="#ff0000"> If you rename or delete a zone, you should perform "shorewall
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stop; shorewall start" to install the change rather than "shorewall restart".</font></b></p>
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<p><b><font size="5" color="#ff0000">Warning 2: </font><font
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color="#ff0000">The order of entries in the /etc/shorewall/zones file is
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significant <a href="#Nested">in some cases</a>.</font></b></p>
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<h2><font color="#660066"><a name="Interfaces"></a> </font>/etc/shorewall/interfaces</h2>
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<p>This file is used to tell the firewall which of your firewall's network
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interfaces are connected to which zone. There will be one entry in /etc/shorewall/interfaces
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for each of your interfaces. Columns in an entry are:</p>
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<ul>
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<li><b> ZONE</b> - A zone defined in the <a href="#Zones">/etc/shorewall/zones</a>
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file or<6F> "-". If you specify "-", you must use the <a
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href="#Hosts"> /etc/shorewall/hosts</a> file to define the zones
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accessed via this interface.</li>
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<li><b> INTERFACE</b> - the name of the interface (examples: eth0,
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ppp0, ipsec+)</li>
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<li><b> BROADCAST</b> - the broadcast address(es) for the sub-network(s)
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attached to the interface. This should be left empty for P-T-P interfaces
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(ppp*, ippp*); if you need to specify options for such an interface, enter
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"-" in this column. If you supply the special value "detect" in this
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column, the firewall will automatically determine the broadcast address.
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In order to use "detect":
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<ul>
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<li>you must have iproute installed</li>
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<li>the interface must be up before you start your firewall</li>
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<li>the interface must only be attached to a single sub-network
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(i.e., there must have a single broadcast address).<2E></li>
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||
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</ul>
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</li>
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<li><b> OPTIONS</b> - a comma-separated list of options. Possible
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||
options include:
|
||
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<p> <b>blacklist</b> - This option causes incoming packets on this
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interface to be checked against the <a
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href="#Blacklist">blacklist</a>.<b><br>
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<br>
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dhcp</b> - The interface is assigned an IP address via DHCP or is
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used by a DHCP server running on the firewall. The firewall will
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||
be configured to allow DHCP traffic to and from the interface even
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||
when the firewall is stopped. You may also wish to use this option if you
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||
have a static IP but you are on a LAN segment that has a lot of Laptops
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that use DHCP and you select the <b>norfc1918 </b>option (see below).</p>
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<p> <b> noping</b> - ICMP echo-request (ping) packets addressed to
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the firewall will be ignored by this interface.<br>
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||
<br>
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<b>filterping </b>- ICMP echo-request (ping) packets addressed to the
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firewall will be handled according to the /etc/shorewall/rules and /etc/shorewall/policy
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file. If the applicable policy is DROP or REJECT and you have supplied
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||
your own /etc/shorewall/icmpdef file then these 'ping' requests will be
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||
passed through the rules in that file before being dropped or rejected.
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If neither <b>noping </b>nor <b>filterping</b> is specified then the firewall
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||
will automatically ACCEPT these 'ping' requests. If both <b>noping</b>
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||
and <b>filterping </b>are specified, <b>filterping</b> takes precedence.</p>
|
||
|
||
<p> <b> routestopped</b> - Beginning with Shorewall 1.3.4, this option
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||
is deprecated in favor of the <a href="#Routestopped">/etc/shorewall/routestopped</a>
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file. When the firewall is stopped, traffic to and from this interface
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||
will be accepted and routing will occur between this interface and
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other <i>routestopped </i>interfaces.</p>
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||
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<p> <b> norfc1918</b> - Packets arriving on this interface and that
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have a source address that is reserved in RFC 1918 or in other RFCs will
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be dropped after being optionally logged. If <a href="#Conf">packet mangling
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is enabled in /etc/shorewall/shorewall.conf</a> , then packets arriving
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on this interface that have a destination address that is reserved by
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one of these RFCs will also be logged and dropped.<br>
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<br>
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Addresses blocked by the standard <a href="#rfc1918"> <b>rfc1918 </b>file</a>
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include those addresses reserved by RFC1918 plus other ranges reserved
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by the IANA or by other RFCs.</p>
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<p> Beware that as IPv4 addresses become in increasingly short supply,
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ISPs are beginning to use RFC 1918 addresses within their own infrastructure.
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Also, many cable and DSL "modems" have an RFC 1918 address that can be
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used through a web browser for management and monitoring functions. If
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you want to specify <b>norfc1918</b> on your external interface but need
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||
to allow access to certain addresses from the above list, see <a
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href="FAQ.htm#faq14">FAQ 14.</a></p>
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<p> <b> routefilter</b> - Invoke the Kernel's route filtering
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(anti-spoofing) facility on this interface. The kernel will reject
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any packets incoming on this interface that have a source address that
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would be routed outbound through another interface on the firewall.
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<font color="#ff0000">Warning: </font>If you specify this option
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for an interface then the interface must be up prior to starting the
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firewall.</p>
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<p> <b> multi</b> - The interface has multiple addresses and
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||
you want to be able to route between them. Example: you have two addresses
|
||
on your single local interface eth1, one each in subnets 192.168.1.0/24
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and 192.168.2.0/24 and you want to route between these subnets. Because
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you only have one interface in the local zone, Shorewall won't normally
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create a rule to forward packets from eth1 to eth1. Adding "multi" to
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the entry for eth1 will cause Shorewall to create the loc2loc chain
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and the appropriate forwarding rule.</p>
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<p><b>dropunclean</b> - Packets from this interface that
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are selected by the 'unclean' match target in iptables will
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be <a href="#LogUnclean">optionally logged</a> and then dropped.
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<font color="#ff0000"><b>Warning: This feature requires
|
||
that UNCLEAN match support be configured in your kernel,
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either in the kernel itself or as a module. UNCLEAN support
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||
is broken in some versions of the kernel but appears to
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||
work ok in 2.4.17-rc1.<br>
|
||
<br>
|
||
Update 12/17/2001: </b></font>The unclean match patch
|
||
from 2.4.17-rc1 is <a
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href="ftp://ftp.shorewall.net/pub/shorewall/misc/unclean.patch">available
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||
for download</a>. I am currently running this patch
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||
applied to kernel 2.4.16.</p>
|
||
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<p><b><font color="#ff6633">Update 12/20/2001: </font></b>I've
|
||
seen a number of tcp connection requests with OPT (020405B4<u>0000080A</u>...)
|
||
being dropped in the <i>badpkt</i> chain. This appears
|
||
to be a bug in the remote TCP stack whereby it is 8-byte
|
||
aligning a timestamp (TCP option 8) but rather than padding
|
||
with 0x01 it is padding with 0x00. It's a tough call whether
|
||
to deny people access to your servers because of this
|
||
rather minor bug in their networking software. If you
|
||
wish to disable the check that causes these connections
|
||
to be dropped, <a
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||
href="ftp://ftp.shorewall.net/pub/shorewall/misc/unclean1.patch">here's
|
||
a kernel patch</a> against 2.4.17-rc2.</p>
|
||
|
||
<p><b>logunclean </b>- This option works like <b>dropunclean</b>
|
||
with the exception that packets selected by the 'unclean'
|
||
match target in iptables are logged <i>but not dropped</i>.
|
||
The level at which the packets are logged is determined
|
||
by the setting of <a href="#LogUnclean">LOGUNCLEAN</a>
|
||
and if LOGUNCLEAN has not been set, "info" is assumed.</p>
|
||
|
||
<p><b>proxyarp </b>(Added in version 1.3.5) - This option
|
||
causes Shorewall to set /proc/sys/net/ipv4/conf/<i><interface></i>/proxy_arp
|
||
and is used when implementing Proxy ARP Sub-netting as
|
||
described at <a
|
||
href="http://www.tldp.org/HOWTO/mini/Proxy-ARP-Subnet/">
|
||
http://www.tldp.org/HOWTO/mini/Proxy-ARP-Subnet/</a>. Do <u>
|
||
not</u> set this option if you are implementing Proxy ARP
|
||
through entries in <a href="#ProxyArp">
|
||
/etc/shorewall/proxyarp</a>.</p>
|
||
</li>
|
||
|
||
</ul>
|
||
|
||
<p>Example 1: You have a conventional firewall setup in which eth0 connects
|
||
to a Cable or DSL modem and eth1 connects to your local network and eth0
|
||
gets its IP address via DHCP. You want to ignore ping requests from the
|
||
internet and you want to check all packets entering from
|
||
the internet against the <a href="#Blacklist">black list</a>.
|
||
Your /etc/shorewall/interfaces file would be as follows:</p>
|
||
|
||
<blockquote>
|
||
<table border="1" cellpadding="2" style="border-collapse: collapse;">
|
||
<tbody>
|
||
<tr>
|
||
<td><b> ZONE</b></td>
|
||
<td><b> INTERFACE</b></td>
|
||
<td><b> BROADCAST</b></td>
|
||
<td><b> OPTIONS</b></td>
|
||
</tr>
|
||
<tr>
|
||
<td>net</td>
|
||
<td>eth0</td>
|
||
<td>detect</td>
|
||
<td>dhcp,noping,norfc1918,blacklist</td>
|
||
</tr>
|
||
<tr>
|
||
<td>loc</td>
|
||
<td>eth1</td>
|
||
<td>detect</td>
|
||
<td><EFBFBD></td>
|
||
</tr>
|
||
|
||
|
||
</tbody>
|
||
|
||
</table>
|
||
</blockquote>
|
||
|
||
<p>Example 2: You have a standalone dialup GNU/Linux System. Your /etc/shorewall/interfaces
|
||
file would be:</p>
|
||
|
||
<blockquote>
|
||
<table border="1" cellpadding="2" style="border-collapse: collapse;">
|
||
<tbody>
|
||
<tr>
|
||
<td><b> ZONE</b></td>
|
||
<td><b> INTERFACE</b></td>
|
||
<td><b> BROADCAST</b></td>
|
||
<td><b> OPTIONS</b></td>
|
||
</tr>
|
||
<tr>
|
||
<td>net</td>
|
||
<td>ppp0</td>
|
||
<td><EFBFBD></td>
|
||
<td><EFBFBD></td>
|
||
</tr>
|
||
|
||
|
||
</tbody>
|
||
|
||
</table>
|
||
</blockquote>
|
||
|
||
|
||
<p>Example 3: You have local interface eth1 with two IP
|
||
addresses - 192.168.1.1/24 and 192.168.12.1/24</p>
|
||
|
||
<blockquote>
|
||
<table border="1" cellpadding="2" style="border-collapse: collapse;">
|
||
<tbody>
|
||
<tr>
|
||
<td><b> ZONE</b></td>
|
||
<td><b> INTERFACE</b></td>
|
||
<td><b> BROADCAST</b></td>
|
||
<td><b> OPTIONS</b></td>
|
||
</tr>
|
||
<tr>
|
||
<td>loc</td>
|
||
<td>eth1</td>
|
||
<td>192.168.1.255,192.168.12.255</td>
|
||
<td><EFBFBD></td>
|
||
</tr>
|
||
|
||
|
||
</tbody>
|
||
</table>
|
||
</blockquote>
|
||
|
||
|
||
<h2><font color="#660066"><a name="Hosts"></a> </font>/etc/shorewall/hosts
|
||
Configuration</h2>
|
||
|
||
<p>For most applications, specifying zones entirely in terms of network
|
||
interfaces is sufficient. There may be times though where you need to define
|
||
a zone to be a more general collection of hosts. This is the purpose of
|
||
the /etc/shorewall/hosts file.</p>
|
||
|
||
|
||
<p><b><font color="#ff0000">WARNING: </font>90% of
|
||
Shorewall users don't need to put entries in this file and
|
||
80% of those who try to add such entries do it wrong.
|
||
Unless you are ABSOLUTELY SURE that you need entries in
|
||
this file, don't touch it.</b></p>
|
||
|
||
|
||
<p>Columns in this file are:</p>
|
||
|
||
<ul>
|
||
<li><b> ZONE </b> - A zone defined in the <a href="#Zones">/etc/shorewall/zones</a>
|
||
file.</li>
|
||
<li><b> HOST(S)</b> - The name of a network interface followed by
|
||
a colon (":") followed by either:</li>
|
||
|
||
</ul>
|
||
|
||
|
||
<blockquote>
|
||
|
||
<ol>
|
||
|
||
<li>An IP address (example - eth1:192.168.1.3)</li>
|
||
|
||
<li>A subnet in the form <i><subnet address>/<width>
|
||
</i>(example - eth2:192.168.2.0/2)</li>
|
||
|
||
|
||
</ol>
|
||
|
||
|
||
<p>The interface name much match an entry in /etc/shorewall/interfaces.</p>
|
||
</blockquote>
|
||
|
||
<ul>
|
||
<li><b> OPTIONS</b> - A comma-separated list of options. Currently
|
||
only a single option is defined:</li>
|
||
|
||
</ul>
|
||
|
||
|
||
<blockquote>
|
||
|
||
<p><b>routestopped</b> - Beginning with Shorewall
|
||
1.3.4, this option is deprecated in favor of the
|
||
<a href="#Routestopped">/etc/shorewall/routestopped</a>
|
||
file. When the firewall is stopped, traffic to and from
|
||
this host (these hosts) will be accepted and routing will occur between
|
||
this host and other <i>routestopped </i>interfaces and hosts.</p>
|
||
</blockquote>
|
||
|
||
|
||
<p>If you don't define any hosts for a zone, the hosts in the zone default
|
||
to i0:0.0.0.0/0 , i1:0.0.0.0/0, ... where i0, i1, ... are the interfaces
|
||
to the zone.</p>
|
||
|
||
|
||
<p><b><font size="4" color="#ff0000">Note 1: </font></b> You probably DON'T
|
||
want to specify any hosts for your internet zone since the hosts that
|
||
you specify will be the only ones that you will be able to access without
|
||
adding additional rules.</p>
|
||
|
||
|
||
<p><font color="#ff0000" size="4"><b>Note 2: </b>
|
||
</font> The setting of the MERGE_HOSTS variable
|
||
in <a href="#Conf">/etc/shorewall/shorewall.conf</a>
|
||
has an important effect on how the host file is
|
||
processed. Please read the description of that
|
||
variable carefully.</p>
|
||
|
||
|
||
<p>Example:</p>
|
||
|
||
|
||
<p>Your local interface is eth1 and you have two groups of local hosts that
|
||
you want to make into separate zones:</p>
|
||
|
||
<ul>
|
||
<li>192.168.1.0/25<32></li>
|
||
<li>192.168.1.128/25</li>
|
||
|
||
</ul>
|
||
|
||
|
||
<p> Your /etc/shorewall/interfaces file might look like:</p>
|
||
|
||
|
||
<blockquote>
|
||
<table border="1" cellpadding="2" style="border-collapse: collapse;">
|
||
<tbody>
|
||
<tr>
|
||
<td><b> ZONE</b></td>
|
||
<td><b> INTERFACE</b></td>
|
||
<td><b> BROADCAST</b></td>
|
||
<td><b> OPTIONS</b></td>
|
||
</tr>
|
||
<tr>
|
||
<td>net</td>
|
||
<td>eth0</td>
|
||
<td>detect</td>
|
||
<td>dhcp,noping,norfc1918</td>
|
||
</tr>
|
||
<tr>
|
||
<td>-</td>
|
||
<td>eth1</td>
|
||
<td>detect</td>
|
||
<td><EFBFBD></td>
|
||
</tr>
|
||
|
||
|
||
</tbody>
|
||
|
||
</table>
|
||
</blockquote>
|
||
|
||
|
||
<p> The '-' in the ZONE column for eth1 tells Shorewall that eth1 interfaces
|
||
to multiple zones.</p>
|
||
|
||
|
||
<p> Your /etc/shorewall/hosts file might look like:</p>
|
||
|
||
|
||
<blockquote> <font
|
||
face="Century Gothic, Arial, Helvetica">
|
||
</font>
|
||
<table border="1" cellpadding="2" style="border-collapse: collapse;">
|
||
<tbody>
|
||
<tr>
|
||
<td><b> ZONE</b></td>
|
||
<td><b> HOST(S)</b></td>
|
||
<td><b> OPTIONS</b></td>
|
||
</tr>
|
||
<tr>
|
||
<td>loc1</td>
|
||
<td>eth1:192.168.1.0/25</td>
|
||
<td><EFBFBD></td>
|
||
</tr>
|
||
<tr>
|
||
<td>loc2</td>
|
||
<td>eth1:192.168.1.128/25</td>
|
||
<td>routestopped</td>
|
||
</tr>
|
||
|
||
|
||
</tbody>
|
||
|
||
</table>
|
||
</blockquote>
|
||
|
||
|
||
<p> Hosts in 'loc2' can communicate with the firewall while Shorewall is
|
||
stopped -- those in 'loc1' cannot.</p>
|
||
|
||
|
||
<h4><font color="#660066"><a name="Nested"></a> Nested and Overlapping Zones</font></h4>
|
||
|
||
|
||
<p> The /etc/shorewall/interfaces and /etc/shorewall/hosts file allow
|
||
you to define nested or overlapping zones. Such overlapping/nested zones
|
||
are allowed and Shorewall processes zones in the order that they appear
|
||
in the /etc/shorewall/zones file. So if you have nested zones, you want
|
||
the sub-zone to appear before the super-zone and in the case of overlapping
|
||
zones, the rules that will apply to hosts that belong to both zones is
|
||
determined by which zone appears first in /etc/shorewall/zones.</p>
|
||
|
||
|
||
<p> Hosts that belong to more than one zone may be managed by the rules
|
||
of all of those zones. This is done through use of the special <a
|
||
href="#CONTINUE">CONTINUE policy</a> described below.</p>
|
||
|
||
|
||
<h2><font color="#660066"><a name="Policy"></a>
|
||
</font>/etc/shorewall/policy Configuration.</h2>
|
||
|
||
|
||
<p>This file is used to describe the firewall policy regarding establishment
|
||
of connections. Connection establishment is described in terms of <i>clients</i>
|
||
who initiate connections and <i> servers </i>who receive those connection
|
||
requests. Policies defined in /etc/shorewall/policy describe which zones
|
||
are allowed to establish connections with other zones.</p>
|
||
|
||
|
||
<p>Policies established in /etc/shorewall/policy can be viewed as default
|
||
policies. If no rule in /etc/shorewall/rules applies to a particular
|
||
connection request then the policy from /etc/shorewall/policy is applied.</p>
|
||
|
||
|
||
<p>Four policies are defined:</p>
|
||
|
||
<ul>
|
||
<li><b> ACCEPT</b> - The connection is allowed.</li>
|
||
<li><b> DROP</b> - The connection request is ignored.</li>
|
||
<li><b> REJECT</b> - The connection request is rejected with an RST
|
||
(TCP) or an ICMP destination-unreachable packet being returned to the
|
||
client.</li>
|
||
<li><b> CONTINUE </b> - The connection is neither ACCEPTed, DROPped
|
||
nor REJECTed. CONTINUE may be used when one or both of the zones named
|
||
in the entry are sub-zones of or intersect with another zone. For more
|
||
information, see below.<2E></li>
|
||
|
||
</ul>
|
||
|
||
|
||
<p> For each policy specified in /etc/shorewall/policy, you can indicate
|
||
that you want a message sent to your system log each time that the policy
|
||
is applied.</p>
|
||
|
||
|
||
<p> Entries in /etc/shorewall/policy have four columns as follows:</p>
|
||
|
||
|
||
<ol>
|
||
|
||
<li> <b> SOURCE</b> - The name of a client
|
||
zone (a zone defined in the <a href="#Zones"> /etc/shorewall/zones
|
||
file</a> , the <a href="#FW">name of the firewall</a> zone or "all").</li>
|
||
|
||
<li> <b> DEST</b> - The name of a destination
|
||
zone (a zone defined in the <a href="#Zones"> /etc/shorewall/zones
|
||
file</a> , the <a href="#FW">name of the firewall</a> zone or "all").</li>
|
||
|
||
<li> <b> POLICY</b> - The default policy
|
||
for connection requests from the SOURCE zone to the DESTINATION zone.</li>
|
||
|
||
<li> <b> LOG LEVEL</b> - Optional. If left
|
||
empty, no log message is generated when the policy is applied. Otherwise,
|
||
this column should contain an integer or name indicating a syslog level.
|
||
See the syslog.conf man page for a description of each log level.</li>
|
||
|
||
<li> <b>LIMIT:BURST </b>- Optional. If left
|
||
empty, TCP connection requests from the <b>SOURCE</b> zone to the <b>DEST</b>
|
||
zone will not be rate-limited. Otherwise, this column specifies the maximum
|
||
rate at which TCP connection requests will be accepted followed by a colon
|
||
(":") followed by the maximum burst size that will be tolerated. Example:
|
||
<b> 10/sec:40</b> specifies that the maximum rate of TCP connection
|
||
requests allowed will be 10 per second and a burst of 40 connections will
|
||
be tolerated. Connection requests in excess of these limits will be dropped.</li>
|
||
|
||
|
||
</ol>
|
||
|
||
|
||
<p> In the SOURCE and DEST columns, you can enter "all" to indicate all
|
||
zones.<2E></p>
|
||
|
||
|
||
<p> The policy file installed by default is as follows:</p>
|
||
|
||
|
||
<blockquote> <font
|
||
face="Century Gothic, Arial, Helvetica">
|
||
</font>
|
||
<table border="1" cellpadding="2" style="border-collapse: collapse;">
|
||
<tbody>
|
||
<tr>
|
||
<td><b>SOURCE</b></td>
|
||
<td><b>DEST</b></td>
|
||
<td><b> POLICY</b></td>
|
||
<td><b> LOG LEVEL</b></td>
|
||
<td><b>LIMIT:BURST</b></td>
|
||
</tr>
|
||
<tr>
|
||
<td>loc</td>
|
||
<td>net</td>
|
||
<td>ACCEPT</td>
|
||
<td><EFBFBD></td>
|
||
|
||
<td><EFBFBD></td>
|
||
</tr>
|
||
<tr>
|
||
<td>net</td>
|
||
<td>all</td>
|
||
<td>DROP</td>
|
||
<td>info</td>
|
||
<td><EFBFBD></td>
|
||
</tr>
|
||
<tr>
|
||
<td>all</td>
|
||
<td>all</td>
|
||
<td>REJECT</td>
|
||
<td>info</td>
|
||
<td><EFBFBD></td>
|
||
</tr>
|
||
|
||
|
||
</tbody>
|
||
|
||
</table>
|
||
</blockquote>
|
||
|
||
|
||
<p> This table may be interpreted as follows:</p>
|
||
|
||
<ul>
|
||
<li>All connection requests from the local network to hosts on the
|
||
internet are accepted.</li>
|
||
<li>All connection requests originating from the internet are ignored
|
||
and logged at level KERNEL.INFO.</li>
|
||
<li>All other connection requests are rejected and logged.</li>
|
||
|
||
</ul>
|
||
|
||
<p><b><font size="4" color="#ff0000"> WARNING:</font></b></p>
|
||
|
||
<p><font color="#ff0000"><b> The firewall script processes</b> <b><EFBFBD>the
|
||
/etc/shorewall/policy file from top to bottom and <u>uses the first applicable
|
||
policy that it finds.</u> For example, in the following policy file,
|
||
the policy for (loc, loc) connections would be ACCEPT as specified in the
|
||
first entry even though the third entry in the file specifies REJECT.</b></font></p>
|
||
|
||
<blockquote> <font
|
||
face="Century Gothic, Arial, Helvetica"> </font>
|
||
<table border="1" cellpadding="2" style="border-collapse: collapse;">
|
||
<tbody>
|
||
<tr>
|
||
<td><b>SOURCE</b></td>
|
||
<td><b>DEST</b></td>
|
||
<td><b>POLICY</b></td>
|
||
<td><b>LOG LEVEL</b></td>
|
||
<td><b>LIMIT:BURST</b></td>
|
||
</tr>
|
||
<tr>
|
||
<td>loc</td>
|
||
<td>all</td>
|
||
<td>ACCEPT</td>
|
||
<td><EFBFBD></td>
|
||
<td><EFBFBD></td>
|
||
</tr>
|
||
<tr>
|
||
<td>net</td>
|
||
<td>all</td>
|
||
<td>DROP</td>
|
||
<td>info</td>
|
||
<td><EFBFBD></td>
|
||
</tr>
|
||
<tr>
|
||
<td>loc</td>
|
||
<td>loc</td>
|
||
<td>REJECT</td>
|
||
<td>info</td>
|
||
<td><EFBFBD></td>
|
||
</tr>
|
||
|
||
|
||
</tbody>
|
||
|
||
</table>
|
||
</blockquote>
|
||
|
||
<h4><font color="#660066"><a name="CONTINUE"></a>
|
||
The CONTINUE policy</font></h4>
|
||
|
||
<p> Where zones are <a href="#Nested">nested or overlapping</a> , the
|
||
CONTINUE policy allows hosts that are within multiple zones to be managed
|
||
under the rules of all of these zones. Let's look at an example:</p>
|
||
|
||
<p> /etc/shorewall/zones:</p>
|
||
|
||
<blockquote>
|
||
<table border="1" cellpadding="2" style="border-collapse: collapse;">
|
||
<tbody>
|
||
<tr>
|
||
<td><b> ZONE</b></td>
|
||
<td><b> DISPLAY</b></td>
|
||
<td><b> COMMENTS</b></td>
|
||
</tr>
|
||
<tr>
|
||
<td>sam</td>
|
||
<td>Sam</td>
|
||
<td>Sam's system at home</td>
|
||
</tr>
|
||
<tr>
|
||
<td>net</td>
|
||
<td>Internet</td>
|
||
<td>The Internet</td>
|
||
</tr>
|
||
<tr>
|
||
<td>loc</td>
|
||
<td>Loc</td>
|
||
<td>Local Network</td>
|
||
</tr>
|
||
|
||
|
||
</tbody>
|
||
|
||
</table>
|
||
</blockquote>
|
||
|
||
<p> /etc/shorewall/interfaces:</p>
|
||
|
||
<blockquote>
|
||
<table border="1" cellpadding="2" style="border-collapse: collapse;">
|
||
<tbody>
|
||
<tr>
|
||
<td><b> ZONE</b></td>
|
||
<td><b> INTERFACE</b></td>
|
||
<td><b> BROADCAST</b></td>
|
||
<td><b> OPTIONS</b></td>
|
||
</tr>
|
||
<tr>
|
||
<td>-</td>
|
||
<td>eth0</td>
|
||
<td>detect</td>
|
||
<td>dhcp,noping,norfc1918</td>
|
||
</tr>
|
||
<tr>
|
||
<td>loc</td>
|
||
<td>eth1</td>
|
||
<td>detect</td>
|
||
<td>routestopped</td>
|
||
</tr>
|
||
|
||
|
||
</tbody>
|
||
|
||
</table>
|
||
</blockquote>
|
||
|
||
<p> /etc/shorewall/hosts:</p>
|
||
|
||
<blockquote> <font
|
||
face="Century Gothic, Arial, Helvetica"> </font>
|
||
<table border="1" cellpadding="2" style="border-collapse: collapse;">
|
||
<tbody>
|
||
<tr>
|
||
<td><b> ZONE</b></td>
|
||
<td><b> HOST(S)</b></td>
|
||
<td><b> OPTIONS</b></td>
|
||
</tr>
|
||
<tr>
|
||
<td>net</td>
|
||
<td>eth0:0.0.0.0/0</td>
|
||
<td><EFBFBD></td>
|
||
</tr>
|
||
<tr>
|
||
<td>sam</td>
|
||
<td>eth0:206.191.149.197</td>
|
||
<td>routestopped</td>
|
||
</tr>
|
||
|
||
|
||
</tbody>
|
||
|
||
</table>
|
||
</blockquote>
|
||
|
||
<p> Note that Sam's home system is a member of both the <b>sam</b> zone
|
||
and the <b>net</b> zone and <a
|
||
href="#Nested"> as described above</a> , that means that <b>sam</b> must
|
||
be listed before <b>net</b><EFBFBD> in /etc/shorewall/zones.</p>
|
||
|
||
<p> /etc/shorewall/policy:</p>
|
||
|
||
<blockquote> <font
|
||
face="Century Gothic, Arial, Helvetica"> </font><font
|
||
face="Century Gothic, Arial, Helvetica"> </font>
|
||
<table border="1" cellpadding="2" style="border-collapse: collapse;">
|
||
<tbody>
|
||
<tr>
|
||
<td><b> SOURCE</b></td>
|
||
<td><b> DEST</b></td>
|
||
<td><b> POLICY</b></td>
|
||
<td><b> LOG LEVEL</b></td>
|
||
</tr>
|
||
<tr>
|
||
<td>loc</td>
|
||
<td>net</td>
|
||
<td>ACCEPT</td>
|
||
<td><EFBFBD></td>
|
||
</tr>
|
||
<tr>
|
||
<td>sam</td>
|
||
<td>all</td>
|
||
<td>CONTINUE</td>
|
||
<td><EFBFBD></td>
|
||
</tr>
|
||
<tr>
|
||
<td>net</td>
|
||
<td>all</td>
|
||
<td>DROP</td>
|
||
<td>info</td>
|
||
</tr>
|
||
<tr>
|
||
<td>all</td>
|
||
<td>all</td>
|
||
<td>REJECT</td>
|
||
<td>info</td>
|
||
</tr>
|
||
|
||
|
||
|
||
</tbody>
|
||
|
||
</table>
|
||
</blockquote>
|
||
|
||
<p> The second entry above says that when Sam is the client, connection
|
||
requests should first be process under rules where the source zone is <b>sam</b>
|
||
and if there is no match then the connection request should be treated under
|
||
rules where the source zone is <b>net</b>. It is important that this policy
|
||
be listed BEFORE the next policy (<b>net</b> to <b>all</b>).</p>
|
||
|
||
<p> Partial /etc/shorewall/rules:</p>
|
||
|
||
<blockquote> <font
|
||
face="Century Gothic, Arial, Helvetica"> </font><font
|
||
face="Century Gothic, Arial, Helvetica"> </font>
|
||
<table border="1" cellpadding="2" style="border-collapse: collapse;">
|
||
<tbody>
|
||
<tr>
|
||
<td><b>ACTION</b></td>
|
||
<td><b>SOURCE</b></td>
|
||
<td><b>DEST</b></td>
|
||
<td><b> PROTO</b></td>
|
||
<td><b>DEST<br>
|
||
PORT(S)</b></td>
|
||
<td><b>SOURCE<br>
|
||
PORT(S)</b></td>
|
||
<td><b>ORIGINAL<br>
|
||
DEST</b></td>
|
||
</tr>
|
||
<tr>
|
||
<td>...</td>
|
||
<td><EFBFBD></td>
|
||
<td><EFBFBD></td>
|
||
<td><EFBFBD></td>
|
||
<td><EFBFBD></td>
|
||
<td><EFBFBD></td>
|
||
<td><EFBFBD></td>
|
||
</tr>
|
||
<tr>
|
||
<td>DNAT</td>
|
||
<td>sam</td>
|
||
<td>loc:192.168.1.3</td>
|
||
<td>tcp</td>
|
||
<td>ssh</td>
|
||
<td>-</td>
|
||
<td><EFBFBD></td>
|
||
</tr>
|
||
<tr>
|
||
<td>DNAT</td>
|
||
<td>net</td>
|
||
<td>loc:192.168.1.5</td>
|
||
<td>tcp</td>
|
||
<td>www</td>
|
||
<td>-</td>
|
||
<td><EFBFBD></td>
|
||
</tr>
|
||
<tr>
|
||
<td>...</td>
|
||
<td><EFBFBD></td>
|
||
<td><EFBFBD></td>
|
||
<td><EFBFBD></td>
|
||
<td><EFBFBD></td>
|
||
<td><EFBFBD></td>
|
||
<td><EFBFBD></td>
|
||
</tr>
|
||
|
||
|
||
|
||
</tbody>
|
||
|
||
|
||
</table>
|
||
</blockquote>
|
||
|
||
<p> Given these two rules, Sam can connect to the firewall's internet interface
|
||
with ssh and the connection request will be forwarded to 192.168.1.3. Like
|
||
all hosts in the <b>net</b> zone, Sam can connect to the firewall's internet
|
||
interface on TCP port 80 and the connection request will be forwarded to
|
||
192.168.1.5. The order of the rules is not significant.</p>
|
||
|
||
<p> <a name="Exclude"></a>Sometimes it is necessary to suppress port forwarding
|
||
for a sub-zone. For example, suppose that all hosts can SSH to the firewall
|
||
and be forwarded to 192.168.1.5 EXCEPT Sam. When Sam connects to the
|
||
firewall's external IP, he should be connected to the firewall itself.
|
||
Because of the way that Netfilter is constructed, this requires two rules
|
||
as follows:</p>
|
||
|
||
<blockquote>
|
||
<p> <20></p>
|
||
<font
|
||
face="Century Gothic, Arial, Helvetica"> </font><font
|
||
face="Century Gothic, Arial, Helvetica"> </font>
|
||
<table border="1" cellpadding="2" style="border-collapse: collapse;">
|
||
<tbody>
|
||
<tr>
|
||
<td><b>ACTION</b></td>
|
||
<td><b>SOURCE</b></td>
|
||
<td><b>DEST</b></td>
|
||
<td><b> PROTO</b></td>
|
||
<td><b>DEST<br>
|
||
PORT(S)</b></td>
|
||
<td><b>SOURCE<br>
|
||
PORT(S)</b></td>
|
||
<td><b>ORIGINAL<br>
|
||
DEST</b></td>
|
||
</tr>
|
||
<tr>
|
||
<td><EFBFBD></td>
|
||
<td><EFBFBD></td>
|
||
<td><EFBFBD></td>
|
||
<td><EFBFBD></td>
|
||
<td><EFBFBD></td>
|
||
<td><EFBFBD></td>
|
||
<td><EFBFBD></td>
|
||
</tr>
|
||
<tr>
|
||
<td>...</td>
|
||
<td><EFBFBD></td>
|
||
<td><EFBFBD></td>
|
||
<td><EFBFBD></td>
|
||
<td><EFBFBD></td>
|
||
<td><EFBFBD></td>
|
||
<td><EFBFBD></td>
|
||
</tr>
|
||
<tr>
|
||
<td>DNAT</td>
|
||
<td>sam</td>
|
||
<td>fw</td>
|
||
<td>tcp</td>
|
||
<td>ssh</td>
|
||
<td>-</td>
|
||
<td><EFBFBD></td>
|
||
</tr>
|
||
<tr>
|
||
<td>DNAT</td>
|
||
<td>net!sam</td>
|
||
<td>loc:192.168.1.3</td>
|
||
<td>tcp</td>
|
||
<td>ssh</td>
|
||
<td>-</td>
|
||
<td><EFBFBD></td>
|
||
</tr>
|
||
<tr>
|
||
<td>...</td>
|
||
<td><EFBFBD></td>
|
||
<td><EFBFBD></td>
|
||
<td><EFBFBD></td>
|
||
<td><EFBFBD></td>
|
||
<td><EFBFBD></td>
|
||
<td><EFBFBD></td>
|
||
</tr>
|
||
|
||
|
||
|
||
</tbody>
|
||
</table>
|
||
</blockquote>
|
||
|
||
<p>The first rule allows Sam SSH
|
||
access to the firewall. The second
|
||
rule says that any clients from the
|
||
net zone with the exception of those
|
||
in the 'sam' zone should have their
|
||
connection port forwarded to
|
||
192.168.1.3. If you need to exclude
|
||
more than one zone in this way,
|
||
you can list the zones separated
|
||
by commas (e.g., net!sam,joe,fred).
|
||
This technique also may be used
|
||
when the ACTION is REDIRECT.</p>
|
||
|
||
|
||
<h2><font color="#660066"><a name="Rules"></a>
|
||
</font>/etc/shorewall/rules</h2>
|
||
|
||
|
||
<p>The /etc/shorewall/rules file defines exceptions to the policies established
|
||
in the /etc/shorewall/policy file. There is one entry in /etc/shorewall/rules
|
||
for each of these rules.<2E></p>
|
||
|
||
|
||
<p>Entries in the file have the following columns:</p>
|
||
|
||
<ul>
|
||
<li><b>ACTION</b>
|
||
<ul>
|
||
<li>ACCEPT, DROP or REJECT. These have the same meaning here as in
|
||
the policy file above.</li>
|
||
<li>DNAT -- Causes the connection request to be forwarded to the system
|
||
specified in the DEST column (port forwarding). "DNAT" stands for "<u>D</u>estination
|
||
<u>N</u>etwork <u>A</u>ddress <u>T</u>ranslation"</li>
|
||
<li>REDIRECT -- Causes the connection request to be redirected to
|
||
a port on the local (firewall) system.</li>
|
||
|
||
</ul>
|
||
|
||
<p>The ACTION may optionally be followed by ":" and a syslogd log
|
||
level (example: REJECT:info). This causes the packet to be logged at the
|
||
specified level prior to being processed according to the specified ACTION.<br>
|
||
<br>
|
||
The use of DNAT or REDIRECT requires that you have <a
|
||
href="#NatEnabled">NAT enabled</a>.<br>
|
||
<20> </p>
|
||
</li>
|
||
<li><b>SOURCE</b> - Describes the source hosts to which the rule applies..
|
||
The contents of this field must begin with the name of a zone defined
|
||
in /etc/shorewall/zones or $FW. If the ACTION is DNAT or REDIRECT, sub-zones
|
||
may be excluded from the rule by following the initial zone name with
|
||
"!' and a comma-separated list of those sub-zones to be excluded. There
|
||
is an <a href="#Exclude">example</a> above.<br>
|
||
<br>
|
||
The source may be further restricted by adding a colon (":") followed
|
||
by a comma-separated list of qualifiers. Qualifiers are may include:
|
||
|
||
<ul>
|
||
<li>An interface name - refers to any connection requests arriving
|
||
on the specified interface (example loc:eth4).</li>
|
||
<li>An IP address - refers to a connection request from the host with
|
||
the specified address (example net:155.186.235.151)</li>
|
||
<li>A MAC Address in <a href="#MAC">Shorewall format</a>.</li>
|
||
<li>A subnet - refers to a connection request from any host in the
|
||
specified subnet (example net:155.186.235.0/24).</li>
|
||
|
||
</ul>
|
||
</li>
|
||
<li><b>DEST</b> - Describes the destination host(s) to which the rule
|
||
applies. May take any of the forms described above for SOURCE plus the
|
||
following two additional forms:
|
||
<ul>
|
||
<li>An IP address followed by a colon and the port <u>number</u> that
|
||
the server is listening on (service names from /etc/services are
|
||
not allowed - example loc:192.168.1.3:80).<2E></li>
|
||
<li>A single port number (again, service names are not allowed) --
|
||
this form is only allowed if the ACTION is REDIRECT and refers to a
|
||
server running on the firewall itself and listening on the specified
|
||
port.</li>
|
||
|
||
</ul>
|
||
</li>
|
||
<li><b> PROTO</b> - Protocol. Must be a protocol name from /etc/protocols,
|
||
a number, "all" or "related". Specifies the protocol of the connection
|
||
request. "related" should be specified only if you have given ALLOWRELATED="no"
|
||
in /etc/shorewall/shorewall.conf and you wish to override that setting
|
||
for related connections originating with the client(s) and server(s)
|
||
specified in this rule. When "related" is given for the protocol, the
|
||
remainder of the columns should be left blank.</li>
|
||
<li><b> DEST PORT(S)</b> - Port or port range (<low port>:<high
|
||
port>) being connected to. May only be specified if the protocol
|
||
is tcp, udp or icmp. For icmp, this column's contents are interpreted
|
||
as an icmp type. If you don't want to specify DEST PORT(S) but need
|
||
to include information in one of the columns to the right, enter "-"
|
||
in this column. You may give a list of ports and/or port ranges separated
|
||
by commas. Port numbers may be either integers or service names from /etc/services.</li>
|
||
<li><b> SOURCE</b> <b>PORTS(S) </b>- May be used to restrict the
|
||
rule to a particular client port or port range (a port range is specified
|
||
as <low port number>:<high port number>). If you don't want
|
||
to restrict client ports but want to specify something in the next column,
|
||
enter "-" in this column. If you wish to specify a list of port number
|
||
or ranges, separate the list elements with commas (with no embedded white
|
||
space). Port numbers may be either integers or service names from /etc/services.</li>
|
||
<li><b>ORIGINAL DEST</b> - This column may only be non-empty if the
|
||
ACTION is DNAT or REDIRECT.<br>
|
||
<br>
|
||
If DNAT or REDIRECT is the ACTION and the ORIGINAL DEST column is left
|
||
empty, any connection request arriving at the firewall from the SOURCE
|
||
that matches the rule will be forwarded or redirected. This works fine
|
||
for connection requests arriving from the internet where the firewall
|
||
has only a single external IP address. When the firewall has multiple
|
||
external IP addresses or when the SOURCE is other than the internet, there
|
||
will usually be a desire for the rule to only apply to those connection
|
||
requests directed to a particular IP address (see Example 2 below for
|
||
another usage). That IP address (or a comma-separated list of such addresses)
|
||
is specified in the ORIGINAL DEST column.<br>
|
||
<br>
|
||
The IP address may be optionally followed by ":" and a second IP
|
||
address. This latter address, if present, is used as the source address
|
||
for packets forwarded to the server (This is called "Source NAT" or SNAT).<br>
|
||
<br>
|
||
<b><font
|
||
color="#ff6633">Note:<3A> </font> When using SNAT, it is a good idea to qualify
|
||
the source with an IP address or subnet. Otherwise, it is likely that
|
||
SNAT will occur on connections other than those described in the rule.
|
||
The reason for this is that SNAT occurs in the Netfilter POSTROUTING hook
|
||
where it is not possible to restrict the scope of a rule by incoming interface.
|
||
<br>
|
||
<br>
|
||
</b>Example: DNAT<41><54><EFBFBD><EFBFBD> loc<u>:192.168.1.0/24</u><EFBFBD><EFBFBD><EFBFBD> loc:192.168.1.3<EFBFBD><EFBFBD><EFBFBD>
|
||
tcp<EFBFBD><EFBFBD><EFBFBD> www<77><77><EFBFBD> -<2D><><EFBFBD> 206.124.146.179:192.168.1.3<b><br>
|
||
<br>
|
||
</b>If SNAT is not used (no ":" and second IP address), the
|
||
original source address is used. If you want any destination address
|
||
to match the rule but want to specify SNAT, simply use a colon followed
|
||
by the SNAT address.</li>
|
||
|
||
</ul>
|
||
|
||
|
||
|
||
<p><b> <font face="Century Gothic, Arial, Helvetica"> <a
|
||
name="PortForward"></a> </font>Example 1. </b> You wish to forward all
|
||
ssh connection requests from the internet to local system 192.168.1.3.<2E></p>
|
||
|
||
<blockquote> <font
|
||
face="Century Gothic, Arial, Helvetica"> </font>
|
||
<table border="1" cellpadding="2" style="border-collapse: collapse;">
|
||
<tbody>
|
||
<tr>
|
||
<td><b>ACTION</b></td>
|
||
<td><b>SOURCE</b></td>
|
||
<td><b>DEST</b></td>
|
||
<td><b> PROTO</b></td>
|
||
<td><b>DEST<br>
|
||
PORT(S)</b></td>
|
||
<td><b>SOURCE<br>
|
||
PORT(S)</b></td>
|
||
<td><b>ORIGINAL<br>
|
||
DEST</b></td>
|
||
</tr>
|
||
<tr>
|
||
<td>DNAT</td>
|
||
<td>net</td>
|
||
<td>loc:192.168.1.3</td>
|
||
<td>tcp</td>
|
||
<td>ssh</td>
|
||
<td><EFBFBD></td>
|
||
<td><EFBFBD></td>
|
||
</tr>
|
||
|
||
|
||
|
||
</tbody>
|
||
|
||
|
||
</table>
|
||
</blockquote>
|
||
|
||
<p><b> Example 2. </b> You want to redirect all local www connection requests
|
||
EXCEPT those to your own
|
||
http server (206.124.146.177)
|
||
to a Squid transparent proxy
|
||
running on the firewall and listening on port 3128. Squid will of course
|
||
require access to remote web servers. This example shows yet
|
||
another use for the ORIGINAL
|
||
DEST column; here, connection
|
||
requests that were NOT
|
||
<a href="#GettingStarted">
|
||
(notice the "!")</a> originally
|
||
destined to 206.124.146.177
|
||
are redirected to local port
|
||
3128.</p>
|
||
|
||
<blockquote> <font
|
||
face="Century Gothic, Arial, Helvetica"> </font>
|
||
<table border="1" cellpadding="2" style="border-collapse: collapse;">
|
||
<tbody>
|
||
<tr>
|
||
<td><b>ACTION</b></td>
|
||
<td><b>SOURCE</b></td>
|
||
<td><b>DEST</b></td>
|
||
<td><b> PROTO</b></td>
|
||
<td><b>DEST<br>
|
||
PORT(S)</b></td>
|
||
<td><b>SOURCE<br>
|
||
PORT(S)</b></td>
|
||
<td><b>ORIGINAL<br>
|
||
DEST</b></td>
|
||
</tr>
|
||
<tr>
|
||
<td>REDIRECT</td>
|
||
<td>loc</td>
|
||
<td>3128</td>
|
||
<td>tcp</td>
|
||
<td>www</td>
|
||
<td><EFBFBD></td>
|
||
<td>!206.124.146.177</td>
|
||
</tr>
|
||
<tr>
|
||
<td>ACCEPT</td>
|
||
<td>fw</td>
|
||
<td>net</td>
|
||
<td>tcp</td>
|
||
<td>www</td>
|
||
<td><EFBFBD></td>
|
||
<td><EFBFBD></td>
|
||
</tr>
|
||
|
||
|
||
|
||
</tbody>
|
||
|
||
|
||
</table>
|
||
</blockquote>
|
||
|
||
<p><b> Example 3. </b> You want to run a web server at 155.186.235.222 in
|
||
your DMZ and have it accessible remotely and locally. the DMZ is managed
|
||
by Proxy ARP or by classical sub-netting.</p>
|
||
|
||
<blockquote> <font
|
||
face="Century Gothic, Arial, Helvetica"> </font><font
|
||
face="Century Gothic, Arial, Helvetica"> </font>
|
||
<table border="1" cellpadding="2" style="border-collapse: collapse;">
|
||
<tbody>
|
||
<tr>
|
||
<td><b>ACTION</b></td>
|
||
<td><b>SOURCE</b></td>
|
||
<td><b>DEST</b></td>
|
||
<td><b> PROTO</b></td>
|
||
<td><b>DEST<br>
|
||
PORT(S)</b></td>
|
||
<td><b>SOURCE<br>
|
||
PORT(S)</b></td>
|
||
<td><b>ORIGINAL<br>
|
||
DEST</b></td>
|
||
</tr>
|
||
<tr>
|
||
<td>ACCEPT</td>
|
||
<td>net</td>
|
||
<td>dmz:155.186.235.222</td>
|
||
<td>tcp</td>
|
||
<td>www</td>
|
||
<td>-</td>
|
||
<td><EFBFBD></td>
|
||
</tr>
|
||
<tr>
|
||
<td>ACCEPT</td>
|
||
<td>loc</td>
|
||
<td>dmz:155.186.235.222</td>
|
||
<td>tcp</td>
|
||
<td>www</td>
|
||
<td><EFBFBD></td>
|
||
<td><EFBFBD></td>
|
||
</tr>
|
||
|
||
|
||
|
||
</tbody>
|
||
|
||
|
||
</table>
|
||
</blockquote>
|
||
|
||
<p><b> Example 4. </b> You want to run wu-ftpd on 192.168.2.2 in your masqueraded
|
||
DMZ. Your internet interface address is 155.186.235.151 and you want the
|
||
FTP server to be accessible from the internet in addition to the local
|
||
192.168.1.0/24 and dmz 192.168.2.0/24 subnetworks. Note that since the
|
||
server is in the 192.168.2.0/24 subnetwork, we can assume that access to
|
||
the server from that subnet will not involve the firewall (<a
|
||
href="FAQ.htm#faq2">but see FAQ 2</a>). Note that unless you
|
||
have more than one external
|
||
IP address, you can leave
|
||
the ORIGINAL DEST column
|
||
blank in the first rule.
|
||
You cannot leave it blank
|
||
in the second rule though
|
||
because then <u>all
|
||
ftp connections</u>
|
||
originating in the local
|
||
subnet 192.168.1.0/24 would
|
||
be sent to 192.168.2.2 <u>
|
||
regardless of the site that
|
||
the user was trying to
|
||
connect to</u>. That is
|
||
clearly not what you want
|
||
<img border="0"
|
||
src="images/SY00079.gif" width="20" height="20" align="top">
|
||
.</p>
|
||
|
||
<blockquote> <font
|
||
face="Century Gothic, Arial, Helvetica"> </font><font
|
||
face="Century Gothic, Arial, Helvetica"> </font>
|
||
<table border="1" cellpadding="2" style="border-collapse: collapse;">
|
||
<tbody>
|
||
<tr>
|
||
<td><b>ACTION</b></td>
|
||
<td><b>SOURCE</b></td>
|
||
<td><b>DEST</b></td>
|
||
<td><b> PROTO</b></td>
|
||
<td><b>DEST<br>
|
||
PORT(S)</b></td>
|
||
<td><b>SOURCE<br>
|
||
PORT(S)</b></td>
|
||
<td><b>ORIGINAL<br>
|
||
DEST</b></td>
|
||
</tr>
|
||
<tr>
|
||
<td>DNAT</td>
|
||
<td>net</td>
|
||
<td>dmz:192.168.2.2</td>
|
||
<td>tcp</td>
|
||
<td>ftp</td>
|
||
<td><EFBFBD></td>
|
||
<td><EFBFBD></td>
|
||
</tr>
|
||
<tr>
|
||
<td>DNAT</td>
|
||
<td>loc:192.168.1.0/24</td>
|
||
<td>dmz:192.168.2.2</td>
|
||
<td>tcp</td>
|
||
<td>ftp</td>
|
||
<td>-</td>
|
||
<td>155.186.235.151</td>
|
||
</tr>
|
||
|
||
|
||
|
||
</tbody>
|
||
|
||
|
||
</table>
|
||
</blockquote>
|
||
|
||
|
||
|
||
<p>If you are running wu-ftpd, you should restrict the range of passive
|
||
in your /etc/ftpaccess file. I only need a few simultaneous FTP sessions
|
||
so I use port range 65500-65535. In /etc/ftpaccess, this entry is appropriate:</p>
|
||
|
||
|
||
|
||
<blockquote>
|
||
|
||
|
||
<p> passive ports<74> 0.0.0.0/0 65500 65534</p>
|
||
</blockquote>
|
||
|
||
|
||
|
||
<p>If you are running pure-ftpd, you would include "-p 65500:65534" on
|
||
the pure-ftpd runline.</p>
|
||
|
||
|
||
|
||
<p>The important point here is to ensure that the port range used for FTP
|
||
passive connections is unique and will not overlap with any usage on the
|
||
firewall system.</p>
|
||
|
||
|
||
|
||
<p><b>Example 5. </b>You
|
||
wish to allow unlimited
|
||
DMZ access to the host
|
||
with MAC address
|
||
02:00:08:E3:FA:55.</p>
|
||
|
||
|
||
|
||
<blockquote> <font
|
||
face="Century Gothic, Arial, Helvetica"> </font>
|
||
<table border="1" cellpadding="2" style="border-collapse: collapse;">
|
||
<tbody>
|
||
<tr>
|
||
<td><b>ACTION</b></td>
|
||
<td><b>SOURCE</b></td>
|
||
<td><b>DEST</b></td>
|
||
<td><b> PROTO</b></td>
|
||
<td><b>DEST<br>
|
||
PORT(S)</b></td>
|
||
<td><b>SOURCE<br>
|
||
PORT(S)</b></td>
|
||
<td><b>ORIGINAL<br>
|
||
DEST</b></td>
|
||
</tr>
|
||
<tr>
|
||
<td>ACCEPT</td>
|
||
<td>loc:~02-00-08-E3-FA-55</td>
|
||
<td>dmz</td>
|
||
<td>all</td>
|
||
<td><EFBFBD></td>
|
||
<td><EFBFBD></td>
|
||
<td><EFBFBD></td>
|
||
</tr>
|
||
|
||
|
||
|
||
</tbody>
|
||
</table>
|
||
</blockquote>
|
||
|
||
|
||
|
||
<p><a href="ports.htm"> Look here for information on other services.</a>
|
||
</p>
|
||
|
||
|
||
|
||
<h2><a name="Common">
|
||
</a>/etc/shorewall/common</h2>
|
||
|
||
|
||
|
||
<p>Shorewall allows
|
||
definition of rules that
|
||
apply between all zones.
|
||
By default, these rules
|
||
are defined in the file
|
||
/etc/shorewall/common.def
|
||
but may be modified to
|
||
suit individual
|
||
requirements. Rather
|
||
than modify
|
||
/etc/shorewall/common.def,
|
||
you should copy that
|
||
file to
|
||
/etc/shorewall/common
|
||
and modify that file.</p>
|
||
|
||
|
||
|
||
<p>The /etc/shorewall/common
|
||
file is expected
|
||
to contain iptables
|
||
commands; rather
|
||
than running iptables
|
||
directly, you should
|
||
run it indirectly
|
||
using the Shorewall
|
||
function 'run_iptables'.
|
||
That way, if iptables
|
||
encounters an error, the
|
||
firewall will be safely
|
||
stopped.</p>
|
||
|
||
|
||
|
||
<h2><a name="Masq"></a>
|
||
/etc/shorewall/masq</h2>
|
||
|
||
|
||
|
||
<p>The /etc/shorewall/masq file is used to define classical IP Masquerading
|
||
and Source Network Address Translation<6F> (SNAT). There is one entry in the
|
||
file for each subnet that you want to masquerade. In order to make use of
|
||
this feature, you must have <a href="#NatEnabled">NAT enabled</a> .</p>
|
||
|
||
|
||
|
||
<p> Columns are:</p>
|
||
|
||
<ul>
|
||
<li><b> INTERFACE</b> - The interface that will masquerade the subnet;
|
||
this is normally your internet interface. This interface name can be
|
||
optionally qualified by adding ":" and a subnet or host IP. When this
|
||
qualification is added, only packets addressed to that host or subnet
|
||
will be masqueraded.</li>
|
||
<li><b> SUBNET</b> - The subnet that you want to have masqueraded
|
||
through the INTERFACE. This may be expressed as a single IP address,
|
||
a subnet or an interface name. In the latter instance, the interface
|
||
must be configured and started before Shorewall is started as Shorewall
|
||
will determine the subnet based on information obtained from the 'ip'
|
||
utility.<br>
|
||
<br>
|
||
The subnet may be optionally followed by "!' and a comma-separated
|
||
list of addresses and/or subnets that are to be excluded from masquerading.</li>
|
||
<li><b>ADDRESS</b> - The source address to be used for outgoing
|
||
packets. This column is optional and if left blank, the current primary
|
||
IP address of the interface in the first column is used. If you have
|
||
a static IP on that interface, listing it here makes processing of output
|
||
packets a little less expensive for the firewall.</li>
|
||
|
||
</ul>
|
||
|
||
|
||
<p><b> Example 1: </b> You have eth0 connected to a cable modem and eth1
|
||
connected to your local subnetwork 192.168.9.0/24. Your /etc/shorewall/masq
|
||
file would look like:<3A><><EFBFBD><EFBFBD></p>
|
||
|
||
|
||
<blockquote>
|
||
|
||
<table border="1" cellpadding="2" style="border-collapse: collapse;">
|
||
<tbody>
|
||
<tr>
|
||
<td><b> INTERFACE</b></td>
|
||
<td><b> SUBNET</b></td>
|
||
<td><b>ADDRESS</b></td>
|
||
</tr>
|
||
<tr>
|
||
<td>eth0</td>
|
||
<td>192.168.9.0/24</td>
|
||
<td><EFBFBD></td>
|
||
</tr>
|
||
|
||
|
||
|
||
</tbody>
|
||
|
||
|
||
</table>
|
||
</blockquote>
|
||
|
||
|
||
<p><b> Example 2:</b> You have a number of IPSEC tunnels through ipsec0
|
||
and you want to masquerade traffic from your 192.168.9.0/24 subnet to the
|
||
remote subnet 10.1.0.0/16 only.</p>
|
||
|
||
|
||
<blockquote>
|
||
|
||
<table border="1" cellpadding="2" style="border-collapse: collapse;">
|
||
<tbody>
|
||
<tr>
|
||
<td><b> INTERFACE</b></td>
|
||
<td><b> SUBNET</b></td>
|
||
<td><b>ADDRESS</b></td>
|
||
</tr>
|
||
<tr>
|
||
<td>ipsec0:10.1.0.0/16</td>
|
||
<td>192.168.9.0/24</td>
|
||
<td><EFBFBD></td>
|
||
</tr>
|
||
|
||
|
||
|
||
</tbody>
|
||
|
||
|
||
</table>
|
||
</blockquote>
|
||
|
||
|
||
<p><b> Example 3:</b> You have a DSL line connected on eth0 and a local
|
||
network (192.168.10.0/24)
|
||
connected to eth1.
|
||
You want all local->net
|
||
connections to
|
||
use source address
|
||
206.124.146.176.</p>
|
||
|
||
<blockquote>
|
||
<table border="1" cellpadding="2" style="border-collapse: collapse;">
|
||
<tbody>
|
||
<tr>
|
||
<td><b> INTERFACE</b></td>
|
||
<td><b> SUBNET</b></td>
|
||
<td><b>ADDRESS</b></td>
|
||
</tr>
|
||
<tr>
|
||
<td>eth0</td>
|
||
<td>192.168.10.0/24</td>
|
||
<td>206.124.146.176</td>
|
||
</tr>
|
||
|
||
|
||
|
||
</tbody>
|
||
</table>
|
||
</blockquote>
|
||
|
||
|
||
<p><b>Example 4: </b>
|
||
Same as example 3
|
||
except that you wish
|
||
to exclude
|
||
192.168.10.44 and
|
||
192.168.10.45 from
|
||
the SNAT rule.</p>
|
||
|
||
|
||
|
||
<blockquote>
|
||
|
||
<table border="1" cellpadding="2" style="border-collapse: collapse;">
|
||
<tbody>
|
||
<tr>
|
||
<td><b> INTERFACE</b></td>
|
||
<td><b> SUBNET</b></td>
|
||
<td><b>ADDRESS</b></td>
|
||
</tr>
|
||
<tr>
|
||
<td>eth0</td>
|
||
<td>192.168.10.0/24!192.168.10.44,192.168.10.45</td>
|
||
<td>206.124.146.176</td>
|
||
</tr>
|
||
|
||
|
||
|
||
</tbody>
|
||
</table>
|
||
</blockquote>
|
||
|
||
|
||
<h2><font color="#660066"><b><a name="ProxyArp"></a>
|
||
</b></font>/etc/shorewall/proxyarp</h2>
|
||
|
||
|
||
|
||
<p>If you want to
|
||
use proxy ARP on an
|
||
entire sub-network,
|
||
I suggest that you
|
||
look at
|
||
<a
|
||
href="http://www.tldp.org/HOWTO/mini/Proxy-ARP-Subnet/">
|
||
http://www.tldp.org/HOWTO/mini/Proxy-ARP-Subnet/</a>.
|
||
If you decide
|
||
to use the technique
|
||
described in
|
||
that HOWTO, you
|
||
can set the
|
||
proxy_arp flag
|
||
for an interface
|
||
(/proc/sys/net/ipv4/conf/<i><interface></i>/proxy_arp)
|
||
by including the
|
||
<b> proxyarp</b>
|
||
option in the
|
||
interface's record
|
||
in <a
|
||
href="#Interfaces">
|
||
/etc/shorewall/interfaces</a>.
|
||
When using Proxy ARP
|
||
sub-netting, you do
|
||
<u>NOT</u> include
|
||
any entries in
|
||
/etc/shorewall/proxyarp.
|
||
</p>
|
||
|
||
|
||
|
||
<p>The /etc/shorewall/proxyarp file is used to define <a
|
||
href="ProxyARP.htm">Proxy ARP</a>. The file is
|
||
typically used for
|
||
enabling Proxy ARP
|
||
on a small set of
|
||
systems since you
|
||
need one entry
|
||
in this file
|
||
for each system
|
||
using proxy ARP.
|
||
Columns are:</p>
|
||
|
||
<ul>
|
||
<li><b> ADDRESS</b> - address of the system.</li>
|
||
<li><b> INTERFACE</b> - the interface that connects to the system.
|
||
If the interface is obvious from the subnetting, you may enter "-" in
|
||
this column.</li>
|
||
<li><b> EXTERNAL</b> - the external interface that you want to honor
|
||
ARP requests for the ADDRESS specified in the first column.</li>
|
||
<li><b>HAVEROUTE</b> - If
|
||
you already have
|
||
a route through
|
||
INTERFACE to
|
||
ADDRESS, this
|
||
column should
|
||
contain
|
||
"Yes"
|
||
or
|
||
"yes".
|
||
If you want
|
||
Shorewall to add
|
||
the route, the
|
||
column should
|
||
contain
|
||
"No"
|
||
or
|
||
"no".</li>
|
||
|
||
</ul>
|
||
|
||
<p><font color="#cc6666"><b>Note: After you have made a change to the /etc/shorewall/proxyarp
|
||
file, you may need to flush the ARP cache of all routers on the LAN segment
|
||
connected to the interface specified in the EXTERNAL column of the change/added
|
||
entry(s). If you are having problems communicating between an individual
|
||
host (A) on that segment and a system whose entry has changed, you may need
|
||
to flush the ARP cache on host A as well.</b></font></p>
|
||
|
||
|
||
<p><font color="#cc6666"><b>ISPs typically have ARP configured with long TTL
|
||
(hours!) so if your ISPs router has a stale cache entry (as seen using "tcpdump
|
||
-nei <external interface> host <IP addr>"), it may take a long
|
||
while to time out. I personally have had to contact my ISP and ask them
|
||
to delete a stale entry in order to restore a system to working order after
|
||
changing my proxy ARP settings. </b></font></p>
|
||
|
||
|
||
|
||
<p><b>Example:
|
||
</b> You have public IP addresses 155.182.235.0/28. You configure your
|
||
firewall as follows:</p>
|
||
|
||
<ul>
|
||
<li>eth0 - 155.186.235.1 (internet connection)</li>
|
||
<li>eth1 - 192.168.9.0/24 (masqueraded local systems)</li>
|
||
<li>eth2 - 192.168.10.1 (interface to your DMZ)</li>
|
||
|
||
</ul>
|
||
|
||
|
||
<p> In your DMZ, you want to install a Web/FTP server with public address
|
||
155.186.235.4. On the Web server, you subnet just like the firewall's eth0
|
||
and you configure 155.186.235.1 as the default gateway. In your /etc/shorewall/proxyarp
|
||
file, you will have:</p>
|
||
|
||
|
||
<blockquote>
|
||
|
||
<table border="2" cellpadding="2" style="border-collapse: collapse;">
|
||
<tbody>
|
||
<tr>
|
||
<td><b> ADDRESS</b></td>
|
||
<td><b> INTERFACE</b></td>
|
||
<td><b> EXTERNAL</b></td>
|
||
<td><b>HAVEROUTE</b></td>
|
||
</tr>
|
||
<tr>
|
||
<td>155.186.235.4</td>
|
||
<td>eth2</td>
|
||
<td>eth0</td>
|
||
<td>No</td>
|
||
</tr>
|
||
|
||
|
||
|
||
</tbody>
|
||
|
||
|
||
</table>
|
||
</blockquote>
|
||
|
||
<p> Note: You may want to configure the servers in your DMZ with a subnet
|
||
that is smaller than the subnet of your internet interface. See the Proxy
|
||
ARP Subnet Mini HOWTO (<a
|
||
href="http://www.tldp.org/HOWTO/mini/Proxy-ARP-Subnet/">http://www.tldp.org/HOWTO/mini/Proxy-ARP-Subnet/</a>)
|
||
for details. In this case you will want to place "Yes" in the HAVEROUTE
|
||
column.</p>
|
||
|
||
<p>To learn how I use Proxy ARP in my DMZ, see <a href="myfiles.htm">my configuration
|
||
files</a>.</p>
|
||
|
||
<p><font color="#ff6633"><b>Warning: </b></font>Do not use Proxy ARP and
|
||
FreeS/Wan on the same system unless you are prepared to suffer the consequences.
|
||
If you start or restart Shorewall with an IPSEC tunnel active, the proxied
|
||
IP addresses are mistakenly assigned to the IPSEC tunnel device (ipsecX)
|
||
rather than to the interface that you specify in the INTERFACE column of
|
||
/etc/shorewall/proxyarp. I haven't had the time to debug this problem so I
|
||
can't say if it is a bug in the Kernel or in FreeS/Wan.<2E></p>
|
||
|
||
<p>You <b>might</b> be able to work around this problem using the following
|
||
(I haven't tried it):</p>
|
||
|
||
<p>In /etc/shorewall/init, include:</p>
|
||
|
||
<p><EFBFBD><EFBFBD><EFBFBD><EFBFBD> qt service ipsec stop</p>
|
||
|
||
<p>In /etc/shorewall/start, include:</p>
|
||
|
||
<p><EFBFBD><EFBFBD><EFBFBD> qt service ipsec start</p>
|
||
|
||
|
||
<h2><font color="#660066"><b><a name="NAT"></a>
|
||
</b></font>/etc/shorewall/nat</h2>
|
||
|
||
|
||
|
||
<p>The /etc/shorewall/nat file is used to define static NAT. There is one
|
||
entry in the file for each static NAT relationship that you wish to define.
|
||
In order to make use of this feature, you must have <a
|
||
href="#NatEnabled">NAT enabled</a> .</p>
|
||
|
||
|
||
|
||
<p> <font
|
||
color="#ff0000">
|
||
<b>IMPORTANT: If
|
||
all you want to do
|
||
is forward ports
|
||
to servers behind
|
||
your firewall, you
|
||
do NOT want to use
|
||
static NAT. Port
|
||
forwarding can
|
||
be accomplished
|
||
with simple
|
||
entries in
|
||
the <a
|
||
href="#Rules">
|
||
rules file</a>.
|
||
Also, in most
|
||
cases
|
||
<a href="#ProxyArp">
|
||
Proxy ARP</a>
|
||
provides a
|
||
superior solution
|
||
to static NAT
|
||
because the
|
||
internal systems
|
||
are accessed using
|
||
the same IP
|
||
address internally
|
||
and externally.</b></font></p>
|
||
|
||
|
||
|
||
<p>Columns in an entry are:</p>
|
||
|
||
<ul>
|
||
<li><b> EXTERNAL</b> - External IP address - <u>This should NOT be
|
||
the primary IP address of the interface named in the next column.</u></li>
|
||
<li><b> INTERFACE</b> - Interface that you want the EXTERNAL IP address
|
||
to appear on.</li>
|
||
<li><b> INTERNAL </b> - Internal IP address.</li>
|
||
<li><b>ALL
|
||
INTERFACES</b>
|
||
- If Yes
|
||
or yes (or
|
||
left
|
||
empty),
|
||
NAT will
|
||
be
|
||
effective
|
||
from all
|
||
hosts. If
|
||
No
|
||
or no
|
||
then NAT
|
||
will be
|
||
effective
|
||
only
|
||
through
|
||
the
|
||
interface
|
||
named in
|
||
the
|
||
INTERFACE
|
||
column. <b> Note:</b>
|
||
If two or more NATed systems are connected to the same firewall interface
|
||
and you want them to be able to communicate using their EXTERNAL IP addresses,
|
||
then you will want to specify the <b>multi</b> option in the <a
|
||
href="#Interfaces">/etc/shorewall/interface</a> entry for that interface.</li>
|
||
<li><b>LOCAL</b> - If Yes or yes and the ALL INTERFACES column contains
|
||
Yes or yes, NAT will be effective from the firewall system. <b>Note:
|
||
</b>For this to work, you must be running kernel 2.4.19 or later and
|
||
iptables 1.2.6a or later and you must have enabled<65> <b>CONFIG_IP_NF_NAT_LOCAL</b>
|
||
in your kernel.</li>
|
||
|
||
</ul>
|
||
|
||
<p><b><a href="NAT.htm"> Look here for additional information and an example.</a>
|
||
</b></p>
|
||
|
||
|
||
<h2><font color="#660066"><a name="Tunnels"></a>
|
||
</font>/etc/shorewall/tunnels</h2>
|
||
|
||
|
||
<p> The /etc/shorewall/tunnels file allows you to define IPSec, GRE and
|
||
IPIP tunnels with end-points on your firewall. To use ipsec, you must install
|
||
version 1.9, 1.91 or the current <a
|
||
href="http://www.xs4all.nl/%7Efreeswan/">FreeS/WAN</a> development snapshot.<2E></p>
|
||
|
||
|
||
<p> Note: For kernels 2.4.4 and above, you will need to use version 1.91
|
||
or a development snapshot as patching with version 1.9 results in kernel
|
||
compilation errors.</p>
|
||
|
||
|
||
<p><b><a href="IPSEC.htm"> Instructions for setting up IPSEC tunnels may
|
||
be found here</a> </b>and <b><a href="IPIP.htm">instructions for IPIP
|
||
tunnels are here</a> . </b>Look <a href="PPTP.htm">here</a> for information
|
||
about setting up PPTP
|
||
tunnels under
|
||
Shorewall.</p>
|
||
|
||
|
||
<h2><font color="#660066"><a name="Conf"></a>
|
||
</font>/etc/shorewall/shorewall.conf</h2>
|
||
|
||
|
||
<p> This file is used to set the following firewall parameters:</p>
|
||
|
||
<ul>
|
||
<li><b>NEWNOTSYN </b>- Added in Version 1.3.8<br>
|
||
When set to "Yes" or "yes", Shorewall will filter TCP packets that are not
|
||
part of an established connention and that are not SYN packets (SYN flag
|
||
on - ACK flag off). If set to "No", Shorewall will silently drop such packets.
|
||
If not set or set to the empty value (e.g., "NEWNOTSYN="), NEWNOTSYN=No is
|
||
assumed.<br>
|
||
<br>
|
||
If you have a HA setup with failover to another firewall, you should have
|
||
NEWNOTSYN=Yes on both firewalls. You should also select NEWNOTSYN=Yes if
|
||
you have asymmetric routing.<br>
|
||
</li>
|
||
<li><b>FORWARDPING</b> - Added in Version 1.3.7<br>
|
||
When set to "Yes" or "yes", ICMP echo-request (ping) packets from interfaces
|
||
that specify "filterping" are ACCEPTed by the firewall. When set to "No"
|
||
or "no", such ping requests are silently dropped unless they are handled
|
||
by an explicit entry in the <a href="#Rules">rules file</a>. If not specified,
|
||
"No" is assumed.</li>
|
||
<li><b>LOGNEWNOTSYN</b> - Added in Version 1.3.6<br>
|
||
Beginning with version 1.3.6, Shorewall drops non-SYN TCP packets that
|
||
are not part of an existing connection. If you would like to log these
|
||
packets, set LOGNEWNOTSYN to the syslog level at which you want the packets
|
||
logged. Example: LOGNEWNOTSYN=debug|<br>
|
||
<br>
|
||
<b>Note: </b>Packets logged under this option are usually the result
|
||
of broken remote IP stacks rather than the result of any sort of attempt
|
||
to breach your firewall.<br>
|
||
<20></li>
|
||
<li><b>MERGE_HOSTS </b>- Added in Version 1.3.5<br>
|
||
Prior to 1.3.5, when the <a href="#Hosts">/etc/shorewall/hosts</a> file
|
||
included an entry for a zone then the entire zone had to be defined in
|
||
the /etc/shorewall/hosts file and any associations between the zone and
|
||
interfaces in the <a href="#Interfaces">/etc/shorewall/interfaces</a>
|
||
file were ignored. This behavior is preserved if MERGE_HOSTS=No or if
|
||
MERGE_HOSTS is not set or is set to the empty value.<br>
|
||
<br>
|
||
Beginning with version 1.3.5, if MERGE_HOSTS=Yes, then zone assignments
|
||
in the /etc/shorewall/hosts file are ADDED to those in the /etc/shorewall/interfaces
|
||
file. <br>
|
||
<br>
|
||
Example:<br>
|
||
<br>
|
||
Interfaces File:<br>
|
||
<20>
|
||
<table border="1" cellpadding="2" style="border-collapse: collapse;"
|
||
id="AutoNumber2">
|
||
<tbody>
|
||
<tr>
|
||
<td><u><b>ZONE</b></u></td>
|
||
<td><u><b>HOSTS</b></u></td>
|
||
<td><u><b>BROADCAST</b></u></td>
|
||
<td><u><b>OPTIONS</b></u></td>
|
||
</tr>
|
||
<tr>
|
||
<td>loc</td>
|
||
<td>eth1</td>
|
||
<td>-</td>
|
||
<td>dhcp</td>
|
||
</tr>
|
||
<tr>
|
||
<td>-</td>
|
||
<td>ppp+</td>
|
||
<td><EFBFBD></td>
|
||
<td><EFBFBD></td>
|
||
</tr>
|
||
|
||
</tbody>
|
||
</table>
|
||
|
||
<p><br>
|
||
Hosts File:<br>
|
||
<20></p>
|
||
|
||
<table border="1" cellpadding="2" style="border-collapse: collapse;"
|
||
id="AutoNumber3">
|
||
<tbody>
|
||
<tr>
|
||
<td><u><b>ZONE</b></u></td>
|
||
<td><u><b>HOSTS</b></u></td>
|
||
</tr>
|
||
<tr>
|
||
<td>loc</td>
|
||
<td>ppp+:192.168.12.0/24</td>
|
||
</tr>
|
||
|
||
</tbody>
|
||
</table>
|
||
|
||
<p><font face="Courier"><br>
|
||
</font>With MERGE_HOSTS=No, the<b> loc</b> zone consists of only ppp+:192.168.12.0/24;
|
||
with MERGE_HOSTS=Yes, it includes eth1:0.0.0.0/0 and ppp+:192.168.12.0/24.<br>
|
||
<20> </p>
|
||
</li>
|
||
<li><b>DETECT_DNAT_ADDRS</b> - Added in Version 1.3.4<br>
|
||
If set to "Yes" or "yes", Shorewall will detect the IP address(es) of the
|
||
interface(es) to the source zone and will include this (these) address(es)
|
||
in DNAT rules as the original destination IP address. If set to "No" or "no",
|
||
Shorewall will not detect this (these) address(es) and any destination IP
|
||
address will match the DNAT rule. If not specified or empty, "DETECT_DNAT_ADDRS=Yes"
|
||
is assumed.<br>
|
||
</li>
|
||
<li><b>MULTIPORT</b> - Added in Version 1.3.2<br>
|
||
If set to "Yes" or "yes", Shorewall will use the Netfilter multiport
|
||
facility. In order to use this facility, your kernel must have multiport
|
||
support (CONFIG_IP_NF_MATCH_MULTIPORT). When this support is used, Shorewall
|
||
will generate a single rule from each record in the /etc/shorewall/rules
|
||
file that meets these criteria:<br>
|
||
<20>
|
||
<ul>
|
||
<li>No port range(s) specified</li>
|
||
<li>Specifies 15 or fewer ports</li>
|
||
|
||
</ul>
|
||
|
||
<p>Rules not meeting those criteria will continue to generate an individual
|
||
rule for each listed port or port range. </p>
|
||
</li>
|
||
<li><b>NAT_BEFORE_RULES</b><br>
|
||
If set to "No" or "no", port forwarding rules can override the contents
|
||
of the <a href="#NAT">/etc/shorewall/nat</a> file. If set to "Yes" or
|
||
"yes", port forwarding rules cannot override static NAT. If not set or
|
||
set to an empty value, "Yes" is assumed.</li>
|
||
<li><b>FW<br>
|
||
</b>This
|
||
parameter
|
||
specifies
|
||
the name
|
||
of the firewall
|
||
zone. If
|
||
not set or
|
||
if set to an
|
||
empty string,
|
||
the value
|
||
"fw"
|
||
is assumed.</li>
|
||
<li><b>SUBSYSLOCK</b><br>
|
||
This parameter should be set to the name of a file that the firewall
|
||
should create if it starts successfully and remove when it stops.
|
||
Creating and removing this file allows Shorewall to work with your
|
||
distribution's initscripts. For RedHat, this should be set to /var/lock/subsys/shorewall.
|
||
For Debian, the value is /var/state/shorewall and in LEAF it is
|
||
/var/run/shorwall.
|
||
Example:
|
||
SUBSYSLOCK=/var/lock/subsys/shorewall.</li>
|
||
<li><b> STATEDIR</b><br>
|
||
This parameter specifies the name of a directory where Shorewall
|
||
stores state information. If the directory doesn't exist when Shorewall
|
||
starts, it will create the directory. Example: STATEDIR=/tmp/shorewall.<br>
|
||
<br>
|
||
<b>NOTE:</b> If you change the STATEDIR variable while the firewall
|
||
is running, create the new directory if necessary then copy the contents
|
||
of the old directory to the new directory. </li>
|
||
<li><b> ALLOWRELATED</b><br>
|
||
This parameter must be assigned the value "Yes" ("yes")
|
||
or "No" ("no") and specifies whether Shorewall allows connection requests
|
||
that are related to an already allowed connection. If you say "No"
|
||
("no"), you can still override this setting by including "related" rules
|
||
in /etc/shorewall/rules ("related" given as the protocol). If you
|
||
specify ALLOWRELATED=No, you will need to include rules in <a
|
||
href="shorewall_extension_scripts.htm">/etc/shorewall/icmpdef</a> to
|
||
handle common ICMP packet types.</li>
|
||
<li><b> MODULESDIR</b><br>
|
||
This parameter specifies the directory where your kernel netfilter
|
||
modules may be found. If you leave the variable empty, Shorewall
|
||
will supply the value "/lib/modules/`uname -r`/kernel/net/ipv4/netfilter.</li>
|
||
<li><b> LOGRATE </b> and <b> LOGBURST</b><br>
|
||
These parameters set the match rate and initial burst size for
|
||
logged packets. Please see the iptables man page for a description of
|
||
the behavior of these parameters (the iptables option --limit is set by
|
||
LOGRATE and --limit-burst is set by LOGBURST). If both parameters are
|
||
set empty, no rate-limiting will occur.<br>
|
||
<br>
|
||
Example:<br>
|
||
<20><><EFBFBD> LOGRATE=10/minute<br>
|
||
<20><><EFBFBD> LOGBURST=5<br>
|
||
<20></li>
|
||
<li><b>LOGFILE</b><br>
|
||
This
|
||
parameter
|
||
tells the
|
||
/sbin/shorewall
|
||
program where
|
||
to look for
|
||
Shorewall
|
||
messages when
|
||
processing the
|
||
"show
|
||
log",
|
||
"monitor",
|
||
"status"
|
||
and
|
||
"hits"
|
||
commands. If
|
||
not assigned
|
||
or if assigned
|
||
an empty
|
||
value,
|
||
/var/log/messages
|
||
is assumed.</li>
|
||
<li><b>NAT_ENABLED</b><br>
|
||
This parameter determines whether Shorewall supports NAT operations.<2E>NAT
|
||
operations include:<br>
|
||
<br>
|
||
<20><><EFBFBD> Static NAT<br>
|
||
<20><><EFBFBD> Port Forwarding<br>
|
||
<20><><EFBFBD> Port Redirection<br>
|
||
<20><><EFBFBD> Masquerading<br>
|
||
<br>
|
||
If the parameter has no value or has a value of "Yes" or
|
||
"yes" then NAT is enabled. If the parameter has a value of "no" or
|
||
"No" then NAT is disabled.<br>
|
||
</li>
|
||
<li><b> MANGLE_ENABLED</b><br>
|
||
This parameter determines if packet mangling is enabled. If the
|
||
parameter has no value or has a value of "Yes" or "yes" than
|
||
packet mangling is enabled. If the parameter has a value of "no"
|
||
or "No" then packet mangling is disabled. If packet mangling is disabled,
|
||
the /etc/shorewall/tos file is ignored.<br>
|
||
</li>
|
||
<li><b> IP_FORWARDING</b><br>
|
||
This parameter determines whether Shorewall enables or disables
|
||
IPV4 Packet Forwarding (/proc/sys/net/ipv4/ip_forward). Possible
|
||
values are:<br>
|
||
<br>
|
||
<20><><EFBFBD> On or on - packet forwarding will be enabled.<br>
|
||
<20><><EFBFBD> Off or off - packet forwarding will be disabled.<br>
|
||
<20><><EFBFBD> Keep or keep - Shorewall will neither enable nor disable
|
||
packet forwarding.<br>
|
||
<br>
|
||
If this variable is not set or is given an empty value (IP_FORWARD="")
|
||
then IP_FORWARD=On is assumed.<br>
|
||
</li>
|
||
<li><b>ADD_IP_ALIASES</b><br>
|
||
This parameter determines whether Shorewall automatically adds
|
||
the
|
||
<i>external </i>address(es) in <a href="#NAT">/etc/shorewall/nat</a>
|
||
. If the variable is set to "Yes" or "yes" then Shorewall automatically
|
||
adds these aliases. If it is set to "No" or "no", you must add
|
||
these aliases yourself using your distribution's network configuration
|
||
tools.<br>
|
||
<br>
|
||
If this variable is not set or is given an empty value (ADD_IP_ALIASES="")
|
||
then ADD_IP_ALIASES=Yes is assumed.</li>
|
||
<li><b>ADD_SNAT_ALIASES</b><br>
|
||
This parameter determines whether Shorewall automatically adds the SNAT
|
||
<i> ADDRESS </i>in <a href="#Masq">/etc/shorewall/masq</a>. If the
|
||
variable is set to "Yes" or "yes" then Shorewall automatically adds these
|
||
addresses. If it is set to "No" or "no", you must add these addresses
|
||
yourself using your distribution's network configuration tools.<br>
|
||
<br>
|
||
If this variable is not set or is given an empty value (ADD_SNAT_ALIASES="")
|
||
then ADD_SNAT_ALIASES=No is assumed.<br>
|
||
</li>
|
||
<li><b>LOGUNCLEAN</b><br>
|
||
This
|
||
parameter
|
||
determines the
|
||
logging level
|
||
of
|
||
mangled/invalid
|
||
packets
|
||
controlled by
|
||
the '<a href="#Unclean">dropunclean
|
||
and logunclean</a>'
|
||
interface
|
||
options.
|
||
If LOGUNCLEAN
|
||
is empty
|
||
(LOGUNCLEAN=)
|
||
then packets
|
||
selected
|
||
by 'dropclean'
|
||
are dropped
|
||
silently
|
||
('logunclean'
|
||
packets
|
||
are logged
|
||
under the
|
||
'info' log
|
||
level).
|
||
Otherwise,
|
||
these packets
|
||
are logged at
|
||
the specified
|
||
level
|
||
(Example:
|
||
LOGUNCLEAN=debug).</li>
|
||
<li><b>BLACKLIST_DISPOSITION</b><br>
|
||
This
|
||
parameter
|
||
determines the
|
||
disposition of
|
||
packets from
|
||
blacklisted
|
||
hosts. It may
|
||
have the value
|
||
DROP if the
|
||
packets are to
|
||
be dropped or
|
||
REJECT
|
||
if the
|
||
packets are to
|
||
be replied
|
||
with an ICMP
|
||
port
|
||
unreachable
|
||
reply or a TCP
|
||
RST (tcp
|
||
only). If you
|
||
do not assign
|
||
a value or if
|
||
you assign an
|
||
empty value
|
||
then DROP
|
||
is assumed.</li>
|
||
<li><b>BLACKLIST_LOGLEVEL</b><br>
|
||
This
|
||
paremter
|
||
determines if
|
||
packets from
|
||
blacklisted
|
||
hosts are
|
||
logged and it
|
||
determines the
|
||
syslog level
|
||
that they are
|
||
to be logged
|
||
at. Its value
|
||
is a syslog
|
||
log level
|
||
(Example:
|
||
BLACKLIST_LOGLEVEL=debug).
|
||
If you
|
||
do not
|
||
assign a value
|
||
or if you
|
||
assign an
|
||
empty value
|
||
then packets
|
||
from
|
||
blacklisted
|
||
hosts are not
|
||
logged.</li>
|
||
<li><b>CLAMPMSS</b><br>
|
||
This
|
||
parameter
|
||
enables the
|
||
TCP Clamp MSS
|
||
to PMTU
|
||
feature of
|
||
Netfilter and
|
||
is usually
|
||
required when
|
||
your internet
|
||
connection is
|
||
through PPPoE
|
||
or PPTP. If
|
||
set to
|
||
"Yes"
|
||
or
|
||
"yes",
|
||
the feature is
|
||
enabled.
|
||
If left
|
||
blank or
|
||
set to
|
||
"No"
|
||
or "no",
|
||
the feature
|
||
is not
|
||
enabled.
|
||
Note: This
|
||
option
|
||
requires
|
||
CONFIG_IP_NF_TARGET_TCPMSS
|
||
<a href="kernel.htm">in
|
||
your kernel</a>.</li>
|
||
<li><b>ROUTE_FILTER</b><br>
|
||
If this parameter is given the value "Yes" or "yes" then route filtering
|
||
(anti-spoofing) is enabled on all network interfaces. The default
|
||
value is "no".</li>
|
||
|
||
</ul>
|
||
|
||
|
||
|
||
<h2><a name="modules"></a>
|
||
/etc/shorewall/modules Configuration</h2>
|
||
|
||
|
||
|
||
<p>The file /etc/shorewall/modules contains commands for loading the kernel
|
||
modules required by Shorewall-defined firewall rules. Shorewall will source
|
||
this file during start/restart provided that it exists and that the directory
|
||
specified by the MODULESDIR parameter exists (see <a href="#Conf">/etc/shorewall/shorewall.conf</a>
|
||
above).</p>
|
||
|
||
|
||
|
||
<p>The file that is released with Shorewall calls the Shorewall function
|
||
"loadmodule" for the set of modules that I load.</p>
|
||
|
||
|
||
|
||
<p>The <i>loadmodule</i> function is called as follows:</p>
|
||
|
||
|
||
|
||
<blockquote>
|
||
|
||
|
||
<p>loadmodule
|
||
<i><modulename>
|
||
</i>[ <i> <module parameters> </i>]</p>
|
||
</blockquote>
|
||
|
||
|
||
|
||
<p>where</p>
|
||
|
||
|
||
|
||
<blockquote>
|
||
|
||
|
||
|
||
<p><i><modulename><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD></i></p>
|
||
|
||
|
||
|
||
<blockquote>
|
||
|
||
|
||
|
||
<p>is the name of the modules without the trailing ".o" (example
|
||
ip_conntrack).</p>
|
||
</blockquote>
|
||
|
||
|
||
|
||
<p><i> <module parameters></i></p>
|
||
|
||
|
||
|
||
<blockquote>
|
||
|
||
|
||
|
||
<p> Optional parameters to the insmod utility.</p>
|
||
</blockquote>
|
||
</blockquote>
|
||
|
||
|
||
|
||
|
||
<p> The function determines if the module named by <i><modulename>
|
||
</i> is already loaded and if not then the function determines if the
|
||
".o" file corresponding to the module exists in the <i>moduledirectory</i>;
|
||
if so, then the following command is executed:</p>
|
||
|
||
|
||
|
||
|
||
<blockquote>
|
||
|
||
|
||
|
||
<p> insmod <i>moduledirectory</i>/<i><modulename></i>.o <i><module
|
||
parameters></i></p>
|
||
</blockquote>
|
||
|
||
|
||
|
||
|
||
<p> If the file doesn't exist, the function determines of the ".o.gz"
|
||
file corresponding to the module exists in the <i>moduledirectory</i>. If
|
||
it does, the function assumes that the running configuration supports compressed
|
||
modules and execute the following command:</p>
|
||
|
||
|
||
|
||
|
||
<blockquote>
|
||
|
||
|
||
|
||
<p> insmod <i>moduledirectory/<modulename>.</i>o.gz <<i>module
|
||
parameters></i></p>
|
||
</blockquote>
|
||
|
||
|
||
|
||
|
||
<h2><a name="TOS"></a>
|
||
/etc/shorewall/tos Configuration</h2>
|
||
|
||
|
||
|
||
|
||
<p> The /etc/shorewall/tos file allows you to set the Type of Service field
|
||
in packet headers based on packet source, packet destination, protocol,
|
||
source port and destination port.<2E>In order for this file to be processed
|
||
by Shorewall, you must have <a href="#MangleEnabled">mangle support enabled</a>
|
||
.</p>
|
||
|
||
|
||
|
||
|
||
<p> Entries in the file have the following columns:</p>
|
||
|
||
|
||
<ul>
|
||
<li><b> SOURCE</b> -- The source zone. May be qualified by following
|
||
the zone name with a colon (":") and either an IP address, an IP subnet,
|
||
a MAC address in <a href="#MAC">Shorewall Format</a> or the name
|
||
of an interface. This column may also contain the <a href="#FW">name of
|
||
the firewall</a>
|
||
zone to
|
||
indicate packets originating on the firewall itself or "all" to
|
||
indicate any source.</li>
|
||
<li><b> DEST</b> -- The destination zone. May be qualified by following
|
||
the zone name with a colon (":") and either an IP address or an IP
|
||
subnet. Because packets are marked prior to routing, you may not specify
|
||
the name of an interface. This column may also contain<69> "all"
|
||
to indicate any destination.</li>
|
||
<li><b> PROTOCOL</b> -- The name of a protocol in /etc/protocols or
|
||
the protocol's number.</li>
|
||
<li><b> SOURCE PORT(S)</b> -- The source port or a port range. For
|
||
all ports, place a hyphen ("-") in this column.</li>
|
||
<li><b> DEST PORT(S)</b><EFBFBD> -- The destination port or a port range.
|
||
To indicate all ports, place a hyphen ("-") in this column.</li>
|
||
<li><b> TOS</b> -- The type of service. Must be one of the following:</li>
|
||
|
||
</ul>
|
||
|
||
|
||
|
||
<blockquote>
|
||
|
||
|
||
<blockquote>
|
||
|
||
|
||
<p> Minimize-Delay (16)<br>
|
||
Maximize-Throughput (8)<br>
|
||
Maximize-Reliability (4)<br>
|
||
Minimize-Cost (2)<br>
|
||
Normal-Service (0)</p>
|
||
</blockquote>
|
||
</blockquote>
|
||
|
||
|
||
|
||
<p> The /etc/shorewall/tos file that is included with Shorewall contains
|
||
the following entries.</p>
|
||
|
||
|
||
|
||
<blockquote>
|
||
<table border="2" cellpadding="2" style="border-collapse: collapse;">
|
||
<tbody>
|
||
|
||
<tr>
|
||
<td><b>SOURCE</b></td>
|
||
<td><b>DEST</b></td>
|
||
<td><b>PROTOCOL</b></td>
|
||
<td><b>SOURCE<br>
|
||
PORT(S)</b></td>
|
||
<td><b>DEST PORT(S)</b></td>
|
||
<td><b>TOS</b></td>
|
||
</tr>
|
||
<tr>
|
||
<td>all</td>
|
||
<td>all</td>
|
||
<td>tcp</td>
|
||
<td>-</td>
|
||
<td>ssh</td>
|
||
<td>16</td>
|
||
</tr>
|
||
<tr>
|
||
<td>all</td>
|
||
<td>all</td>
|
||
<td>tcp</td>
|
||
<td>ssh</td>
|
||
<td>-</td>
|
||
<td>16</td>
|
||
</tr>
|
||
<tr>
|
||
<td>all</td>
|
||
<td>all</td>
|
||
<td>tcp</td>
|
||
<td>-</td>
|
||
<td>ftp</td>
|
||
<td>16</td>
|
||
</tr>
|
||
<tr>
|
||
<td>all</td>
|
||
<td>all</td>
|
||
<td>tcp</td>
|
||
<td>ftp</td>
|
||
<td>-</td>
|
||
<td>16</td>
|
||
</tr>
|
||
<tr>
|
||
<td>all</td>
|
||
<td>all</td>
|
||
<td>tcp</td>
|
||
<td>-</td>
|
||
<td>ftp-data</td>
|
||
<td>8</td>
|
||
</tr>
|
||
<tr>
|
||
<td>all</td>
|
||
<td>all</td>
|
||
<td>tcp</td>
|
||
<td>ftp-data</td>
|
||
<td>-</td>
|
||
<td>8</td>
|
||
</tr>
|
||
|
||
|
||
|
||
|
||
</tbody>
|
||
|
||
|
||
|
||
</table>
|
||
</blockquote>
|
||
|
||
|
||
|
||
<p><b>WARNING: </b>Users have reported that odd routing problems result from
|
||
adding the ESP and AH protocols to the /etc/shorewall/tos file. </p>
|
||
|
||
|
||
|
||
<h2><a name="Blacklist"></a>/etc/shorewall/blacklist</h2>
|
||
|
||
|
||
|
||
<p>Each
|
||
line
|
||
in
|
||
/etc/shorewall/blacklist
|
||
contains
|
||
|
||
an
|
||
IP
|
||
address, a MAC address in <a href="#MAC">Shorewall
|
||
Format</a>
|
||
or
|
||
subnet
|
||
address.
|
||
Example:</p>
|
||
|
||
|
||
<pre> 130.252.100.69<br> 206.124.146.0/24</pre>
|
||
|
||
|
||
|
||
<p>Packets
|
||
<u><b>from</b></u>
|
||
hosts
|
||
listed
|
||
in
|
||
|
||
the
|
||
blacklist
|
||
file
|
||
will
|
||
be
|
||
disposed
|
||
|
||
of
|
||
according
|
||
to
|
||
the
|
||
value
|
||
assigned
|
||
|
||
to
|
||
the <a href="#Conf">BLACKLIST_DISPOSITION</a>
|
||
and
|
||
<a href="#Conf">BLACKLIST_LOGLEVEL </a>variables
|
||
in
|
||
/etc/shorewall/shorewall.conf.
|
||
|
||
Only
|
||
packets
|
||
arriving
|
||
on
|
||
interfaces
|
||
|
||
that
|
||
have
|
||
the
|
||
'<a href="#Interfaces">blacklist</a>'
|
||
|
||
option
|
||
in
|
||
/etc/shorewall/interfaces
|
||
are
|
||
|
||
checked
|
||
against
|
||
the
|
||
blacklist. The black list is
|
||
designed to prevent listed hosts/subnets from accessing services on <u><b>your</b></u>
|
||
network.<br>
|
||
</p>
|
||
<p>Beginning with Shorewall 1.3.8, the blacklist file has three columns:<br>
|
||
</p>
|
||
<ul>
|
||
<li><b>ADDRESS/SUBNET - </b>As described above.</li>
|
||
<li><b>PROTOCOL</b> - Optional. If specified, only packets specifying this
|
||
protocol will be blocked.</li>
|
||
<li><b>PORTS - </b>Optional; may only be given if PROTOCOL is tcp, udp
|
||
or icmp. Expressed as a comma-separated list of port numbers or service names
|
||
(from /etc/services). If present, only packets destined for the specified
|
||
protocol and one of the listed ports are blocked. When the PROTOCOL is icmp,
|
||
the PORTS column contains a comma-separated list of ICMP type numbers or
|
||
names (see "iptables -h icmp").<br>
|
||
</li>
|
||
</ul>
|
||
|
||
|
||
|
||
<p>Shorewall also has a <a href="blacklisting_support.htm">dynamic blacklist
|
||
capability.</a></p>
|
||
|
||
|
||
|
||
<p><font color="#cc6666"><b>IMPORTANT: The Shorewall blacklist file is <u>NOT</u>
|
||
designed to police your users' web browsing -- to do that, I suggest that
|
||
you install and configure Squid (<a href="http://www.squid-cache.org">http://www.squid-cache.org</a>).
|
||
</b></font></p>
|
||
|
||
|
||
|
||
|
||
<h2><a name="rfc1918"></a>/etc/shorewall/rfc1918 (Added in Version 1.3.1)</h2>
|
||
|
||
|
||
|
||
|
||
<p>This file lists the subnets affected by the <a href="#Interfaces"><i>norfc1918</i>
|
||
interface option</a>. Columns in the file are:</p>
|
||
|
||
|
||
|
||
|
||
<ul>
|
||
|
||
<li><b>SUBNET</b> - The subnet using VLSM notation (e.g., 192.168.0.0/16).</li>
|
||
|
||
<li><b>TARGET<i> </i></b>- What to do with packets to/from the
|
||
SUBNET:
|
||
<ul>
|
||
|
||
<li><b>RETURN</b> - Process the packet normally thru the rules
|
||
and policies.</li>
|
||
|
||
<li><b>DROP</b> - Silently drop the packet.</li>
|
||
|
||
<li><b>logdrop</b> - Log then drop the packet.</li>
|
||
|
||
|
||
</ul>
|
||
|
||
</li>
|
||
|
||
</ul>
|
||
|
||
|
||
|
||
|
||
<h2><a name="Routestopped"></a>25. /etc/shorewall/routestopped (Added in Version
|
||
1.3.4)</h2>
|
||
|
||
|
||
|
||
|
||
<p>This fine defines the hosts that are accessible from the firewall when
|
||
the firewall is stopped.<2E> Columns in the file are:</p>
|
||
|
||
|
||
|
||
|
||
<ul>
|
||
|
||
<li><b>INTERFACE </b>- The firewall interface through which the
|
||
host(s) comminicate with the firewall.</li>
|
||
|
||
<li><b>HOST(S) </b>- (Optional) - A comma-separated list of IP/Subnet
|
||
addresses. If not supplied or supplied as "-" then 0.0.0.0/0 is assumed.</li>
|
||
|
||
</ul>
|
||
|
||
|
||
|
||
|
||
<p>Example: When your firewall is stopped, you want firewall accessibility
|
||
from local hosts 192.168.1.0/24 and from your DMZ. Your DMZ interfaces through
|
||
eth1 and your local hosts through eth2.</p>
|
||
|
||
|
||
|
||
|
||
<blockquote>
|
||
|
||
<table border="2" style="border-collapse: collapse;" id="AutoNumber1"
|
||
cellpadding="2">
|
||
|
||
<tbody>
|
||
<tr>
|
||
|
||
<td><u><b>INTERFACE</b></u></td>
|
||
|
||
<td><u><b>HOST(S)</b></u></td>
|
||
|
||
</tr>
|
||
|
||
<tr>
|
||
|
||
<td>eth2</td>
|
||
|
||
<td>192.168.1.0/24</td>
|
||
|
||
</tr>
|
||
|
||
<tr>
|
||
|
||
<td>eth1</td>
|
||
|
||
<td>-</td>
|
||
|
||
</tr>
|
||
|
||
|
||
</tbody>
|
||
</table>
|
||
</blockquote>
|
||
|
||
|
||
|
||
|
||
<p><font size="2"> Updated 9/16/2002 - <a href="support.htm">Tom Eastep</a>
|
||
</font></p>
|
||
|
||
|
||
|
||
<p><font face="Trebuchet MS"><a href="copyright.htm"><font size="2">Copyright</font>
|
||
<20> <font size="2">2001, 2002 Thomas M. Eastep.</font></a></font></p>
|
||
|
||
|
||
<font
|
||
face="Century Gothic, Arial, Helvetica">
|
||
|
||
|
||
|
||
</font><br>
|
||
<br>
|
||
</body>
|
||
</html>
|