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3803 lines
225 KiB
HTML
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
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<html>
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<head>
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<meta http-equiv="Content-Type"
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content="text/html; charset=windows-1252">
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<meta name="GENERATOR" content="Microsoft FrontPage 5.0">
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<meta name="ProgId" content="FrontPage.Editor.Document">
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<title>Shorewall 1.4 Documentation</title>
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<base target="_self">
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<meta name="Microsoft Theme" content="none, default">
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<meta name="Microsoft Border" content="none, default">
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<meta name="author" content="Tom Eastep">
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</head>
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<body>
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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 1.4 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.
|
||
Step-by-step instructions for configuring Shorewall
|
||
in common setups may be found in the <a
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||
href="shorewall_quickstart_guide.htm">QuickStart Guides</a>.</h2>
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||
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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 in /etc/shorewall that can
|
||
be used to establish the values of shell variables for use
|
||
in other files.</li>
|
||
<li><b> <a href="#Conf">shorewall.conf</a></b>
|
||
-- a parameter file installed in /etc/shorewall that
|
||
is used to set several firewall parameters.</li>
|
||
<li><b> <a href="#Zones">zones</a></b>
|
||
- a parameter file installed in /etc/shorewall that defines
|
||
a network partitioning into "zones"</li>
|
||
<li><b> <a href="#Policy">policy</a></b>
|
||
-- a parameter file installed in /etc/shorewall/ that
|
||
establishes overall firewall policy.</li>
|
||
<li><b> <a href="#Rules">rules</a>
|
||
</b> -- a parameter file installed in /etc/shorewall and
|
||
used to express firewall rules that are exceptions to
|
||
the high-level policies established in /etc/shorewall/policy.</li>
|
||
<li><b><a href="#Blacklist">blacklist</a>
|
||
-- </b>a parameter file installed in /etc/shorewall and
|
||
used to list blacklisted IP/subnet/MAC addresses.</li>
|
||
<li><b><a href="#ECN">ecn</a></b> -- a parameter file installed in /etc/shorewall
|
||
and used to selectively disable Explicit Congestion Notification (ECN - RFC
|
||
3168).<br>
|
||
</li>
|
||
<li><b> functions</b> -- a set of shell
|
||
functions used by both the firewall and shorewall shell
|
||
programs. Installed in /etc/shorewall prior to version 1.3.2,
|
||
in /var/lib/shorewall in version s 1.3.2-1.3.8 and in /usr/lib/shorewall
|
||
in later versions.</li>
|
||
<li><b> <a href="#modules">modules</a></b>
|
||
-- a parameter file installed in /etc/shorewall and that
|
||
specifies kernel modules and their parameters. Shorewall will
|
||
automatically load the modules specified in this file.</li>
|
||
<li><a
|
||
href="#TOS"><b> tos</b> </a>-- a parameter file installed in
|
||
/etc/shorewall that is used to specify how the Type of Service
|
||
(TOS) field in packets is to be set.<br>
|
||
</li>
|
||
<li><b><a href="#Scripts">common.def</a></b>
|
||
-- a parameter file installed in in /etc/shorewall that
|
||
defines firewall-wide rules that are applied before a DROP
|
||
or REJECT policy is applied.</li>
|
||
<li><b> <a href="#Interfaces">interfaces</a>
|
||
</b> -- a parameter file installed in /etc/shorewall/
|
||
and used to describe the interfaces on the firewall system.</li>
|
||
<li><a href="#Hosts"><b> hosts</b>
|
||
</a>-- a parameter file installed in /etc/shorewall/ and
|
||
used to describe individual hosts or subnetworks in
|
||
zones.</li>
|
||
<li><b><a href="#Maclist">maclist</a> </b>--
|
||
a parameter file installed in /etc/shorewall and used to verify
|
||
the MAC address (and possibly also the IP address(es)) of devices.<br>
|
||
</li>
|
||
<li><b> <a href="#Masq">masq</a></b>
|
||
- This file also describes IP masquerading under Shorewall
|
||
and is installed in /etc/shorewall.</li>
|
||
<li><b><a
|
||
href="shorewall_firewall_structure.htm">firewall</a></b> -- a shell
|
||
program that reads the configuration files in /etc/shorewall
|
||
and configures your firewall. This file is installed
|
||
in your init.d directory (/etc/rc.d/init.d ) where it
|
||
is renamed <i>shorewall.</i> /etc/shorewall/firewall (/var/lib/shorewall/firewall
|
||
in versions 1.3.2-1.3.8 and /usr/lib/shorewall/firewall in 1.3.9
|
||
and later) is a symbolic link to this program.</li>
|
||
<li><b> <a href="#NAT">nat</a></b>
|
||
-- a parameter file in /etc/shorewall used to define <a
|
||
href="#NAT"> static NAT</a> .</li>
|
||
<li><b> <a href="#ProxyArp">proxyarp</a></b>
|
||
-- a parameter file in /etc/shorewall used to define <a
|
||
href="#ProxyArp"> Proxy Arp</a> .</li>
|
||
<li><b><a href="#rfc1918">rfc1918</a></b>
|
||
-- a parameter file in /etc/shorewall used to define the treatment
|
||
of packets under the <a href="#Interfaces">norfc1918 interface
|
||
option</a>.</li>
|
||
<li><b><a href="#Routestopped">routestopped</a></b>
|
||
-- a parameter file in /etc/shorewall used to define those
|
||
hosts that can access the firewall when Shorewall is stopped.</li>
|
||
<li><a
|
||
href="traffic_shaping.htm#tcrules"><b>tcrules</b> </a>--
|
||
a parameter file in /etc/shorewall used to define rules for classifying
|
||
packets for <a href="traffic_shaping.htm">Traffic Shaping/Control</a>.</li>
|
||
<li><b> <a href="#Tunnels">tunnels</a></b>
|
||
-- a parameter file in /etc/shorewall used to define
|
||
IPSec tunnels.</li>
|
||
<li><b> <a href="#Starting">shorewall</a>
|
||
</b> -- a shell program (requiring a Bourne shell or
|
||
derivative) used to control and monitor
|
||
the firewall. This should be placed in /sbin or in /usr/sbin
|
||
(the install.sh script and the rpm install this file
|
||
in /sbin).</li>
|
||
<li><b> version</b> -- a file created
|
||
in /etc/shorewall/ (/var/lib/shorewall in version
|
||
1.3.2-1.3.8 and /usr/lib/shorewall beginning in version 1.3.9)
|
||
that describes the version of Shorewall installed
|
||
on your system.</li>
|
||
|
||
</ul>
|
||
|
||
|
||
<h2><a name="Variables"></a> /etc/shorewall/params</h2>
|
||
|
||
|
||
<p>You may use the file /etc/shorewall/params file to set shell variables
|
||
that you can then use in some of the other configuration
|
||
files.</p>
|
||
|
||
|
||
<p>It is suggested that variable names begin with an upper case letter<font
|
||
size="1"> </font>to distinguish them from variables used internally
|
||
within the Shorewall programs</p>
|
||
|
||
|
||
<p>Example:</p>
|
||
|
||
|
||
<pre><font face="Courier"> NET_IF=eth0<br> NET_BCAST=130.252.100.255<br> NET_OPTIONS=blacklist,norfc1918</font></pre>
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||
|
||
<p>Example (/etc/shorewall/interfaces record):</p>
|
||
|
||
<pre> <font face="Courier">net $NET_IF $NET_BCAST $NET_OPTIONS</font></pre>
|
||
|
||
<p>The result will be the same as if the record had been written</p>
|
||
|
||
<pre> <font face="Courier">net eth0 130.252.100.255 blacklist,norfc1918</font></pre>
|
||
|
||
<p>Variables may be used anywhere in the other configuration
|
||
files.</p>
|
||
|
||
|
||
<h2><b><a name="Zones"></a> </b>/etc/shorewall/zones</h2>
|
||
|
||
|
||
<p>This file is used to define the network zones. There is one entry
|
||
in /etc/shorewall/zones for each zone; Columns in an entry
|
||
are:</p>
|
||
|
||
|
||
<ul>
|
||
<li><b> ZONE</b> - short name for the
|
||
zone. The name should be 5 characters or less in length
|
||
and consist of lower-case letters or numbers. Short names must
|
||
begin with a letter and the name assigned to the firewall is
|
||
reserved for use by Shorewall itself. Note that the output produced
|
||
by iptables is much easier to read if you select short names
|
||
that are three characters or less in length. The name "all"
|
||
may not be used as a zone name nor may the zone name assigned to
|
||
the firewall itself via the FW variable in <a href="#Conf">/etc/shorewall/shorewall.conf</a>.</li>
|
||
<li><b> DISPLAY</b> - The name of the
|
||
zone as displayed during Shorewall startup.</li>
|
||
<li><b> COMMENTS</b> - Any comments
|
||
that you want to make about the zone. Shorewall ignores
|
||
these comments.</li>
|
||
|
||
</ul>
|
||
|
||
|
||
<p>The /etc/shorewall/zones file released with Shorewall is as follows:</p>
|
||
|
||
|
||
<table border="1" style="border-collapse: collapse;" cellpadding="2">
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||
<tbody>
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||
<tr>
|
||
<td><b> ZONE</b></td>
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||
<td><b> DISPLAY</b></td>
|
||
<td><b> COMMENTS</b></td>
|
||
</tr>
|
||
<tr>
|
||
<td>net</td>
|
||
<td>Net</td>
|
||
<td>Internet</td>
|
||
</tr>
|
||
<tr>
|
||
<td>loc</td>
|
||
<td>Local</td>
|
||
<td>Local networks</td>
|
||
</tr>
|
||
<tr>
|
||
<td>dmz</td>
|
||
<td>DMZ</td>
|
||
<td>Demilitarized zone</td>
|
||
</tr>
|
||
|
||
|
||
|
||
</tbody>
|
||
|
||
</table>
|
||
|
||
|
||
<p>You may add, delete and modify entries in the /etc/shorewall/zones file
|
||
as desired so long as you have at least one zone defined.</p>
|
||
|
||
|
||
<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
|
||
stop; shorewall start" to install the change rather than
|
||
"shorewall restart".</font></b></p>
|
||
|
||
|
||
<p><b><font size="5" color="#ff0000">Warning 2: </font><font
|
||
color="#ff0000">The order of entries in the /etc/shorewall/zones file is
|
||
significant <a href="#Nested">in some cases</a>.</font></b></p>
|
||
|
||
|
||
<h2><font color="#660066"><a name="Interfaces"></a> </font>/etc/shorewall/interfaces</h2>
|
||
|
||
|
||
<p>This file is used to tell the firewall which of your firewall's network
|
||
interfaces are connected to which zone. There will be
|
||
one entry in /etc/shorewall/interfaces for each of your interfaces.
|
||
Columns in an entry are:</p>
|
||
|
||
<ul>
|
||
<li><b> ZONE</b> - A zone defined in
|
||
the <a href="#Zones">/etc/shorewall/zones</a> file or
|
||
"-". If you specify "-", you must use the <a href="#Hosts">
|
||
/etc/shorewall/hosts</a> file to define the zones
|
||
accessed via this interface.</li>
|
||
<li><b> INTERFACE</b> - the name of
|
||
the interface (examples: eth0, ppp0, ipsec+). Each interface
|
||
can be listed on only one record in this file. <font
|
||
color="#ff0000"><b>D</b><b>O NOT INCLUDE THE LOOPBACK INTERFACE
|
||
(lo) IN THIS FILE!!!</b></font></li>
|
||
<li><b> BROADCAST</b> - the broadcast
|
||
address(es) for the sub-network(s) attached to the interface.
|
||
This should be left empty for P-T-P interfaces (ppp*, ippp*);
|
||
if you need to specify options for such an interface, enter "-"
|
||
in this column. If you supply the special value "detect" in this
|
||
column, the firewall will automatically determine the broadcast
|
||
address. In order to use "detect":
|
||
|
||
|
||
<ul>
|
||
<li>the
|
||
interface must be up before you start your firewall</li>
|
||
<li>the interface must only be attached
|
||
to a single sub-network (i.e., there must have a single broadcast
|
||
address). </li>
|
||
|
||
|
||
|
||
</ul>
|
||
|
||
</li>
|
||
<li><b> OPTIONS</b> - a comma-separated
|
||
list of options. Possible options include:
|
||
|
||
|
||
|
||
<p> <b>tcpflags </b>(added in version 1.3.11) - This option causes Shorewall
|
||
to make sanity checks on the header flags in TCP packets arriving on this
|
||
interface. Checks include Null flags, SYN+FIN, SYN+RST and FIN+URG+PSH; these
|
||
flag combinations are typically used for "silent" port scans. Packets failing
|
||
these checks are logged according to the TCP_FLAGS_LOG_LEVEL option in<a
|
||
href="#Conf"> /etc/shorewall/shorewall.conf</a> and are disposed of according
|
||
to the TCP_FLAGS_DISPOSITION option.<br>
|
||
<b><br>
|
||
blacklist</b> - This option causes incoming packets
|
||
on this interface to be checked against the <a
|
||
href="#Blacklist">blacklist</a>.<b><br>
|
||
<br>
|
||
dhcp</b> - The interface is assigned an
|
||
IP address via DHCP or is used by a DHCP server running
|
||
on the firewall. The firewall will be configured to allow
|
||
DHCP traffic to and from the interface even when the firewall
|
||
is stopped. You may also wish to use this option if you have a
|
||
static IP but you are on a LAN segment that has a lot of Laptops
|
||
that use DHCP and you select the <b>norfc1918 </b>option
|
||
(see below).</p>
|
||
|
||
|
||
|
||
|
||
<p> <b>norfc1918</b> - Packets arriving on this interface and that
|
||
have a source address that is reserved in RFC 1918 or in other
|
||
RFCs will be dropped after being optionally logged. If <a
|
||
href="#Conf">packet mangling is enabled in /etc/shorewall/shorewall.conf</a>
|
||
, then packets arriving on this interface that have a
|
||
destination address that is reserved by one of these RFCs will
|
||
also be logged and dropped.<br>
|
||
<br>
|
||
Addresses blocked by the standard <a
|
||
href="#rfc1918"> <b>rfc1918 </b>file</a> include those
|
||
addresses reserved by RFC1918 plus other ranges reserved by
|
||
the IANA or by other RFCs.</p>
|
||
|
||
|
||
|
||
|
||
<p> Beware that as IPv4 addresses become in increasingly short supply,
|
||
ISPs are beginning to use RFC 1918 addresses within their
|
||
own infrastructure. Also, many cable and DSL "modems" have
|
||
an RFC 1918 address that can be used through a web browser for
|
||
management and monitoring functions. If you want to specify
|
||
<b>norfc1918</b> on your external interface but need to allow
|
||
access to certain addresses from the above list, see <a
|
||
href="FAQ.htm#faq14">FAQ 14.</a></p>
|
||
|
||
|
||
|
||
|
||
<p> <b> routefilter</b> - Invoke the Kernel's route filtering
|
||
(anti-spoofing) facility on this interface. The kernel
|
||
will reject any packets incoming on this interface that have
|
||
a source address that would be routed outbound through another
|
||
interface on the firewall. <font color="#ff0000">Warning:
|
||
</font>If you specify this option for an interface then
|
||
the interface must be up prior to starting the firewall.</p>
|
||
|
||
|
||
|
||
|
||
<p> <b>dropunclean</b> - Packets from this interface that
|
||
are selected by the 'unclean' match target in iptables will
|
||
be <a href="#LogUnclean">optionally logged</a> and then dropped.
|
||
<font color="#ff0000"><b>Warning: This feature
|
||
requires that UNCLEAN match support be configured in your
|
||
kernel, either in the kernel itself or as a module. UNCLEAN
|
||
support is broken in some versions of the kernel
|
||
but appears to 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 href="ftp://ftp.shorewall.net/pub/shorewall/misc/unclean.patch">available
|
||
for download</a>. I am currently running
|
||
this patch applied to kernel 2.4.16.</p>
|
||
|
||
|
||
|
||
<p><font color="#ff0000"><b>Update 12/20/2001: </b></font>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
|
||
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>.<br>
|
||
<br>
|
||
<b>maclist</b> (Added in version 1.3.10)
|
||
- If this option is specified, all connection requests from this
|
||
interface are subject to <a href="MAC_Validation.html">MAC Verification</a>.
|
||
May only be specified for ethernet interfaces.</p>
|
||
</li>
|
||
|
||
</ul>
|
||
|
||
<p>My recommendations concerning options:<br>
|
||
</p>
|
||
|
||
<ul>
|
||
<li>External Interface -- <b>tcpflags,blacklist,norfc1918,routefilter</b></li>
|
||
<li>Wireless Interface -- <b>maclist,routefilter,tcpflags</b><br>
|
||
</li>
|
||
<li>Don't use <b>dropunclean</b> -- It's broken
|
||
in my opinion</li>
|
||
<li>Use <b>logunclean</b> only when you are trying
|
||
to debug a problem</li>
|
||
<li>Use <b>dhcp </b>and <b>proxyarp</b> when needed.<br>
|
||
</li>
|
||
|
||
</ul>
|
||
|
||
<p> </p>
|
||
|
||
|
||
<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
|
||
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,norfc1918,blacklist</td>
|
||
</tr>
|
||
<tr>
|
||
<td>loc</td>
|
||
<td>eth1</td>
|
||
<td>detect</td>
|
||
<td> <br>
|
||
</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> <br>
|
||
</td>
|
||
<td> <br>
|
||
</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> <br>
|
||
</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>The only times that you need
|
||
entries in /etc/shorewall/hosts are:<br>
|
||
</b></p>
|
||
<ol>
|
||
<li><b>You have more than one zone connecting through a single interface;
|
||
or</b></li>
|
||
<li><b>You have a zone that has multiple subnetworks that connect through
|
||
a single interface and you want the Shorewall box to route traffic between
|
||
those subnetworks.</b><br>
|
||
</li>
|
||
</ol>
|
||
<b>IF YOU DON'T HAVE EITHER OF THOSE SITUATIONS THEN DON'T TOUCH THIS FILE!!</b>
|
||
<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 CIDR notation<i>
|
||
</i>(example - eth2:192.168.2.0/24)</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 option</li>
|
||
|
||
</ul>
|
||
|
||
|
||
<blockquote>
|
||
|
||
|
||
<p><b>maclist - </b>Added in version 1.3.10. If specified, connection
|
||
requests from the hosts specified in this entry are subject to
|
||
<a href="MAC_Validation.html">MAC Verification</a>. This option is only
|
||
valid for ethernet interfaces.<br>
|
||
</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: </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>Example 1:</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 </li>
|
||
<li>192.168.1.128/</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,norfc1918</td>
|
||
</tr>
|
||
<tr>
|
||
<td>-</td>
|
||
<td>eth1</td>
|
||
<td>192.168.1.127,192.168.1.255<br>
|
||
</td>
|
||
<td> <br>
|
||
</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> <br>
|
||
</td>
|
||
</tr>
|
||
<tr>
|
||
<td>loc2</td>
|
||
<td>eth1:192.168.1.128/25</td>
|
||
<td><br>
|
||
</td>
|
||
</tr>
|
||
|
||
</tbody>
|
||
</table>
|
||
</blockquote>
|
||
|
||
|
||
|
||
|
||
|
||
<p>Example 2:</p>
|
||
|
||
|
||
|
||
<p>Your local interface is eth1 and you have two groups of local hosts that
|
||
you want to consider as one zone and you want Shorewall to route between
|
||
them:</p>
|
||
|
||
|
||
<ul>
|
||
<li>192.168.1.0/25 </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,norfc1918</td>
|
||
</tr>
|
||
<tr>
|
||
<td>loc<br>
|
||
</td>
|
||
<td>eth1</td>
|
||
<td>192.168.1.127,192.168.1.255<br>
|
||
</td>
|
||
<td> <br>
|
||
</td>
|
||
</tr>
|
||
|
||
|
||
|
||
|
||
</tbody>
|
||
|
||
|
||
</table>
|
||
</blockquote>
|
||
|
||
|
||
|
||
|
||
|
||
<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>loc</td>
|
||
<td>eth1:192.168.1.0/25</td>
|
||
<td> <br>
|
||
</td>
|
||
</tr>
|
||
<tr>
|
||
<td>loc</td>
|
||
<td>eth1:192.168.1.128/25</td>
|
||
<td><br>
|
||
</td>
|
||
</tr>
|
||
|
||
</tbody>
|
||
</table>
|
||
</blockquote>
|
||
|
||
|
||
|
||
|
||
|
||
<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.</li>
|
||
<li><b>NONE</b> - (Added in version 1.4.1) - Shorewall should not set up
|
||
any infrastructure for handling traffic from the SOURCE zone to the DEST
|
||
zone. When this policy is specified, the <b>LOG LEVEL </b>and <b>BURST:LIMIT
|
||
</b>columns must be left blank.<br>
|
||
</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="#Conf">name of the firewall zone</a> 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="#Conf">name of the firewall zone</a> or "all"). Shorewall
|
||
automatically allows all traffic from the firewall to itself so
|
||
the <a href="#Conf">name of the firewall zone</a> cannot appear in both
|
||
the SOURCE and DEST columns.</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 <a
|
||
href="shorewall_logging.html">syslog level</a>.</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. </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> <br>
|
||
</td>
|
||
|
||
<td> <br>
|
||
</td>
|
||
</tr>
|
||
<tr>
|
||
<td>net</td>
|
||
<td>all</td>
|
||
<td>DROP</td>
|
||
<td>info</td>
|
||
<td> <br>
|
||
</td>
|
||
</tr>
|
||
<tr>
|
||
<td>all</td>
|
||
<td>all</td>
|
||
<td>REJECT</td>
|
||
<td>info</td>
|
||
<td> <br>
|
||
</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> 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> <br>
|
||
</td>
|
||
<td> <br>
|
||
</td>
|
||
</tr>
|
||
|
||
<tr>
|
||
<td>net</td>
|
||
<td>all</td>
|
||
<td>DROP</td>
|
||
<td>info</td>
|
||
<td> <br>
|
||
</td>
|
||
</tr>
|
||
<tr>
|
||
<td>loc</td>
|
||
<td>loc</td>
|
||
<td>REJECT</td>
|
||
<td>info</td>
|
||
<td> <br>
|
||
</td>
|
||
</tr>
|
||
|
||
|
||
|
||
|
||
|
||
</tbody>
|
||
|
||
|
||
</table>
|
||
</blockquote>
|
||
|
||
|
||
<h4><a name="IntraZone"></a>IntraZone Traffic</h4>
|
||
Shorewall allows a zone to be associated with more than one interface or
|
||
with multiple networks that interface through a single interface. Beginning
|
||
with Shorewall 1.4.1, Shorewall will ACCEPT all traffic from a zone to itself
|
||
provided that there is no explicit policy governing traffic from that zone
|
||
to itself (an explicit policy does not specify "all" in either the SOURCE
|
||
or DEST column) and that there are no rules concerning connections from that
|
||
zone to itself. If there is an explicit policy or if there are one or more
|
||
rules, then traffic within the zone is handled just like traffic between
|
||
zones is.<br>
|
||
<p>Any time that you have multiple interfaces associated with a single zone,
|
||
you should ask yourself if you really want traffic routed between those interfaces.
|
||
Cases where you might not want that behavior are:<br>
|
||
</p>
|
||
<ol>
|
||
<li>Multiple 'net' interfaces to different ISPs. You don't want to route
|
||
traffic from one ISP to the other through your firewall.</li>
|
||
<li>Multiple VPN clients. You don't necessarily want them to all be able
|
||
to communicate between themselves using your gateway/router.<br>
|
||
</li>
|
||
</ol>
|
||
<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,norfc1918</td>
|
||
</tr>
|
||
<tr>
|
||
<td>loc</td>
|
||
<td>eth1</td>
|
||
<td>detect</td>
|
||
<td><br>
|
||
</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> <br>
|
||
</td>
|
||
</tr>
|
||
|
||
<tr>
|
||
<td>sam</td>
|
||
<td>eth0:206.191.149.197</td>
|
||
<td><br>
|
||
</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> 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> <br>
|
||
</td>
|
||
</tr>
|
||
|
||
<tr>
|
||
<td>sam</td>
|
||
<td>all</td>
|
||
<td>CONTINUE</td>
|
||
<td> <br>
|
||
</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> <br>
|
||
</td>
|
||
<td> <br>
|
||
</td>
|
||
<td> <br>
|
||
</td>
|
||
<td> <br>
|
||
</td>
|
||
<td> <br>
|
||
</td>
|
||
<td> <br>
|
||
</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> <br>
|
||
</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> <br>
|
||
</td>
|
||
</tr>
|
||
<tr>
|
||
<td>...</td>
|
||
<td> <br>
|
||
</td>
|
||
<td> <br>
|
||
</td>
|
||
<td> <br>
|
||
</td>
|
||
<td> <br>
|
||
</td>
|
||
<td> <br>
|
||
</td>
|
||
<td> <br>
|
||
</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> </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> <br>
|
||
</td>
|
||
<td> <br>
|
||
</td>
|
||
<td> <br>
|
||
</td>
|
||
<td> <br>
|
||
</td>
|
||
<td> <br>
|
||
</td>
|
||
<td> <br>
|
||
</td>
|
||
<td> <br>
|
||
</td>
|
||
</tr>
|
||
<tr>
|
||
<td>...</td>
|
||
<td> <br>
|
||
</td>
|
||
<td> <br>
|
||
</td>
|
||
<td> <br>
|
||
</td>
|
||
<td> <br>
|
||
</td>
|
||
<td> <br>
|
||
</td>
|
||
<td> <br>
|
||
</td>
|
||
|
||
</tr>
|
||
<tr>
|
||
<td>DNAT</td>
|
||
<td>sam</td>
|
||
<td>fw</td>
|
||
<td>tcp</td>
|
||
<td>ssh</td>
|
||
<td>-</td>
|
||
<td> <br>
|
||
</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> <br>
|
||
</td>
|
||
</tr>
|
||
<tr>
|
||
<td>...</td>
|
||
<td> <br>
|
||
</td>
|
||
<td> <br>
|
||
</td>
|
||
<td> <br>
|
||
</td>
|
||
<td> <br>
|
||
</td>
|
||
<td> <br>
|
||
</td>
|
||
<td> <br>
|
||
</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. <br>
|
||
</p>
|
||
|
||
<p>Shorewall automatically enables firewall->firewall traffic over the
|
||
loopback interface (lo) -- that traffic cannot be regulated using
|
||
rules and any rule that tries to regulate such traffic will generate
|
||
a warning and will be ignored.<br>
|
||
</p>
|
||
|
||
|
||
|
||
<p>Entries in the file have the following columns:</p>
|
||
|
||
<ul>
|
||
<li><b>ACTION</b>
|
||
|
||
|
||
<ul>
|
||
<li>ACCEPT, DROP, REJECT, CONTINUE.
|
||
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>DNAT- -- The above ACTION (DNAT) generates
|
||
two iptables rules: 1) and header-rewriting rule in the Netfilter
|
||
'nat' table and; 2) an ACCEPT rule in the Netfilter 'filter' table.
|
||
DNAT- works like DNAT but only generates the header-rewriting rule.<br>
|
||
</li>
|
||
<li>REDIRECT -- Causes the connection
|
||
request to be redirected to a port on the local (firewall)
|
||
system.</li>
|
||
<li>LOG - Log the packet -- requires a syslog level (see below).</li>
|
||
|
||
|
||
|
||
</ul>
|
||
|
||
|
||
|
||
<p>The ACTION may optionally be followed by ":" and a <a
|
||
href="shorewall_logging.html">syslog level</a> (example: REJECT:info).
|
||
This causes the packet to be logged at the specified level prior
|
||
to being processed according to the specified ACTION. Note: if the
|
||
ACTION is LOG then you MUST specify a syslog level.<br>
|
||
<br>
|
||
The use of DNAT or REDIRECT requires
|
||
that you have <a href="#NatEnabled">NAT enabled</a>.<br>
|
||
</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,
|
||
$FW or "all". 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>
|
||
If the source is not 'all' then 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). Beginning with Shorwall 1.3.9, the interface
|
||
name may optionally be followed by a colon (":") and an IP address or
|
||
subnet (examples: loc:eth4:192.168.4.22, net:eth0:192.0.2.0/24).</li>
|
||
<li>An IP address - refers to a connection
|
||
request from the host with the specified address
|
||
(example net:155.186.235.151). If the ACTION is DNAT, this must
|
||
not be a DNS name.</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 most 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). <br>
|
||
</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>
|
||
Restrictions:<br>
|
||
|
||
<ul>
|
||
<li>MAC addresses may not be specified.</li>
|
||
<li>In DNAT rules, only an IP address may be given -- DNS names are
|
||
not permitted.</li>
|
||
<li>You may not specify both an IP address and an interface name
|
||
in the DEST column.<br>
|
||
</li>
|
||
|
||
</ul>
|
||
</li>
|
||
<li><b> PROTO</b> - Protocol. Must
|
||
be a protocol name from /etc/protocols, a number or
|
||
"all". Specifies the protocol of the connection request.</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: </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 loc<u>:192.168.1.0/24</u>
|
||
loc:192.168.1.3 tcp www - 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. </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> <br>
|
||
</td>
|
||
<td> <br>
|
||
</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> -<br>
|
||
</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> <br>
|
||
</td>
|
||
<td> <br>
|
||
</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> <br>
|
||
</td>
|
||
</tr>
|
||
|
||
<tr>
|
||
<td>ACCEPT</td>
|
||
<td>loc</td>
|
||
<td>dmz:155.186.235.222</td>
|
||
<td>tcp</td>
|
||
<td>www</td>
|
||
<td> <br>
|
||
</td>
|
||
<td> <br>
|
||
</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> <br>
|
||
</td>
|
||
<td> <br>
|
||
</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 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> <br>
|
||
</td>
|
||
<td> <br>
|
||
</td>
|
||
<td> <br>
|
||
</td>
|
||
</tr>
|
||
|
||
|
||
|
||
|
||
|
||
</tbody>
|
||
|
||
</table>
|
||
</blockquote>
|
||
|
||
|
||
<b>Example
|
||
6.</b> You wish to allow access to the SMTP server in your DMZ
|
||
from all zones.<br>
|
||
|
||
<blockquote>
|
||
|
||
<table cellpadding="2" cellspacing="0" border="1">
|
||
<tbody>
|
||
<tr>
|
||
<td valign="top"><b>ACTION</b><br>
|
||
</td>
|
||
<td valign="top"><b>SOURCE<br>
|
||
</b></td>
|
||
<td valign="top"><b>DEST<br>
|
||
</b></td>
|
||
<td valign="top"><b>PROTO<br>
|
||
</b></td>
|
||
<td valign="top"><b>DEST<br>
|
||
PORT(S)<br>
|
||
</b></td>
|
||
<td valign="top"><b>SOURCE<br>
|
||
PORT(S)<br>
|
||
</b></td>
|
||
<td valign="top"><b>ORIGINAL<br>
|
||
DEST<br>
|
||
</b></td>
|
||
</tr>
|
||
<tr>
|
||
<td valign="top">ACCEPT<br>
|
||
</td>
|
||
<td valign="top">all<br>
|
||
</td>
|
||
<td valign="top">dmz<br>
|
||
</td>
|
||
<td valign="top">tcp<br>
|
||
</td>
|
||
<td valign="top">25<br>
|
||
</td>
|
||
<td valign="top"><br>
|
||
</td>
|
||
<td valign="top"><br>
|
||
</td>
|
||
</tr>
|
||
|
||
|
||
|
||
</tbody>
|
||
|
||
</table>
|
||
<br>
|
||
Note: When 'all' is used as a source or destination,
|
||
intra-zone traffic is not affected. In this example, if there were
|
||
two DMZ interfaces then the above rule would NOT enable SMTP traffic
|
||
between hosts on these interfaces.<br>
|
||
</blockquote>
|
||
<b>Example 7 (For advanced users running Shorewall version
|
||
1.3.13 or later). </b>From the internet, you with to forward tcp
|
||
port 25 directed to 192.0.2.178 and 192.0.2.179 to host 192.0.2.177
|
||
in your DMZ. You also want to allow access from the internet directly
|
||
to tcp port 25 on 192.0.2.177. <br>
|
||
|
||
<blockquote>
|
||
<table cellpadding="2" cellspacing="0" border="1">
|
||
<tbody>
|
||
<tr>
|
||
<td valign="top"><b>ACTION</b><br>
|
||
</td>
|
||
<td valign="top"><b>SOURCE<br>
|
||
</b></td>
|
||
<td valign="top"><b>DEST<br>
|
||
</b></td>
|
||
<td valign="top"><b>PROTO<br>
|
||
</b></td>
|
||
<td valign="top"><b>DEST<br>
|
||
PORT(S)<br>
|
||
</b></td>
|
||
<td valign="top"><b>SOURCE<br>
|
||
PORT(S)<br>
|
||
</b></td>
|
||
<td valign="top"><b>ORIGINAL<br>
|
||
DEST<br>
|
||
</b></td>
|
||
</tr>
|
||
<tr>
|
||
<td valign="top">DNAT-<br>
|
||
</td>
|
||
<td valign="top">net<br>
|
||
</td>
|
||
<td valign="top">dmz:192.0.2.177<br>
|
||
</td>
|
||
<td valign="top">tcp<br>
|
||
</td>
|
||
<td valign="top">25<br>
|
||
</td>
|
||
<td valign="top">0<br>
|
||
</td>
|
||
<td valign="top">192.0.2.178<br>
|
||
</td>
|
||
</tr>
|
||
<tr>
|
||
<td valign="top">DNAT-<br>
|
||
</td>
|
||
<td valign="top">net<br>
|
||
</td>
|
||
<td valign="top">dmz:192.0.2.177<br>
|
||
</td>
|
||
<td valign="top">tcp<br>
|
||
</td>
|
||
<td valign="top">25<br>
|
||
</td>
|
||
<td valign="top">0<br>
|
||
</td>
|
||
<td valign="top">192.0.2.179<br>
|
||
</td>
|
||
</tr>
|
||
<tr>
|
||
<td valign="top">ACCEPT<br>
|
||
</td>
|
||
<td valign="top">net<br>
|
||
</td>
|
||
<td valign="top">dmz:192.0.2.177<br>
|
||
</td>
|
||
<td valign="top">tcp<br>
|
||
</td>
|
||
<td valign="top">25<br>
|
||
</td>
|
||
<td valign="top"><br>
|
||
</td>
|
||
<td valign="top"><br>
|
||
</td>
|
||
</tr>
|
||
|
||
|
||
</tbody>
|
||
</table>
|
||
</blockquote>
|
||
Using "DNAT-" rather than "DNAT" avoids two extra copies
|
||
of the third rule from being generated.<br>
|
||
|
||
<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 (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. Beginning with Shorewall version 1.3.14,
|
||
if you have set ADD_SNAT_ALIASES=Yes in <a href="#Conf">/etc/shorewall/shorewall.conf</a>,
|
||
you can cause Shorewall to create an alias <i>label </i>of the form
|
||
<i>interfacename:digit </i>(e.g., eth0:0) by placing that label
|
||
in this column. See example 5 below. Alias labels created in this way
|
||
allow the alias to be visible to the ipconfig utility. <b>THAT IS
|
||
THE ONLY THING THAT THIS LABEL IS GOOD FOR AND IT MAY NOT APPEAR ANYWHERE
|
||
ELSE IN YOUR SHOREWALL CONFIGURATION.</b></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.
|
||
<b><font color="#ff0000">When using Shorewall 1.3.13 or earlier, when
|
||
an interface name is specified, Shorewall will only masquerade traffic
|
||
from the first subnetwork on the named interface; if the interface interfaces
|
||
to more that one subnetwork, you will need to add additional entries
|
||
to this file for each of those other subnetworks. Beginning with Shorewall
|
||
1.3.14, shorewall will masquerade/SNAT traffic from any host that is routed
|
||
through the named interface.</font></b><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. If you specify an address in
|
||
this column, it must be an IP address configured on the INTERFACE or
|
||
you must have ADD_SNAT_ALIASES enabled in <a href="#Conf">/etc/shorewall/shorewall.conf.</a></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: </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> <br>
|
||
</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> <br>
|
||
</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>
|
||
|
||
|
||
<b>Example 5 (Shorewall version >= 1.3.14): </b>You have a second
|
||
IP address (206.124.146.177) assigned to you and wish to use it for
|
||
SNAT of the subnet 192.168.12.0/24. You want to give that address the
|
||
name eth0:0. You must have ADD_SNAT_ALIASES=Yes in <a href="#Conf">/etc/shorewall/shorewall.conf</a>.<br>
|
||
|
||
<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>eth0:0</td>
|
||
<td>192.168.12.0/24</td>
|
||
<td>206.124.146.177</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><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. </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> qt service ipsec stop</p>
|
||
|
||
<p>In /etc/shorewall/start, include:</p>
|
||
|
||
<p> 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. Beginning
|
||
with Shorewall version 1.3.14, if you have set ADD_IP_ALIASES=Yes in
|
||
<a href="#Conf">/etc/shorewall/shorewall.conf</a>, <20>you can specify
|
||
an alias label of the form <i>interfacename:digit </i>(e.g., eth0:0)
|
||
and Shorewall will create the alias with that label. Alias labels created
|
||
in this way allow the alias to be visible to the ipconfig utility.
|
||
<b>THAT IS THE ONLY THING THAT THIS LABEL IS GOOD FOR AND IT MAY
|
||
NOT APPEAR ANYWHERE ELSE IN YOUR SHOREWALL CONFIGURATION.</b><EFBFBD></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.</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 <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, IPIP,
|
||
<a href="http://openvpn.sourceforge.net/">OpenVPN</a> and PPTP
|
||
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. </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> <b><a href="IPIP.htm">instructions
|
||
for IPIP and GRE tunnels are here</a></b>, <b><a
|
||
href="OPENVPN.html">instructions for OpenVPN tunnels are here</a></b>, and
|
||
<b><a href="PPTP.htm">instructions for PPTP tunnels are here</a>.</b></p>
|
||
|
||
<h2><a name="Conf"></a>/etc/shorewall/shorewall.conf</h2>
|
||
|
||
|
||
|
||
<p> This file is used to set the following firewall parameters:</p>
|
||
|
||
<ul>
|
||
<li><b>CLEAR_TC</b> - Added at
|
||
version 1.3.13<br>
|
||
If this option is set to 'No' then Shorewall won't clear the
|
||
current traffic control rules during [re]start. This setting is intended
|
||
for use by people that prefer to configure traffic shaping when the
|
||
network interfaces come up rather than when the firewall is started.
|
||
If that is what you want to do, set TC_ENABLED=Yes and CLEAR_TC=No and
|
||
do not supply an /etc/shorewall/tcstart file. That way, your traffic
|
||
shaping rules can still use the 'fwmark' classifier based on packet marking
|
||
defined in /etc/shorewall/tcrules. If not specified, CLEAR_TC=Yes is assumed.<br>
|
||
</li>
|
||
<li><b>MARK_IN_FORWARD_CHAIN </b>- Added at version 1.3.12<br>
|
||
If your kernel has a FORWARD chain in the mangle table,
|
||
you may set MARK_IN_FORWARD_CHAIN=Yes to cause the marking specified
|
||
in the <a href="traffic_shaping.htm#tcrules">tcrules file</a> to
|
||
occur in that chain rather than in the PREROUTING chain. This permits
|
||
you to mark inbound traffic based on its destination address when
|
||
SNAT or Masquerading are in use. To determine if your kernel has a FORWARD
|
||
chain in the mangle table, use the "/sbin/shorewall show mangle" command;
|
||
if a FORWARD chain is displayed then your kernel will support this
|
||
option. If this option is not specified or if it is given the empty
|
||
value (e.g., MARK_IN_FORWARD_CHAIN="") then MARK_IN_FORWARD_CHAIN=No
|
||
is assumed.<br>
|
||
</li>
|
||
<li><b>RFC1918_LOG_LEVEL - </b>Added at version 1.3.12<br>
|
||
This parameter determines the level at which packets
|
||
logged under the <a href="Documentation.htm#rfc1918">'norfc1918'
|
||
mechanism </a> are logged. The value must be a valid <a
|
||
href="shorewall_logging.html">syslog level</a> and if no level is given,
|
||
then info is assumed. Prior to Shorewall version 1.3.12, these packets
|
||
are always logged at the info level.</li>
|
||
<li><b>TCP_FLAGS_DISPOSITION - </b>Added in Version
|
||
1.3.11<br>
|
||
Determines the disposition of TCP packets that fail
|
||
the checks enabled by the <a href="#Interfaces%5C">tcpflags</a>
|
||
interface option and must have a value of ACCEPT (accept the packet),
|
||
REJECT (send an RST response) or DROP (ignore the packet). If not
|
||
set or if set to the empty value (e.g., TCP_FLAGS_DISPOSITION="")
|
||
then TCP_FLAGS_DISPOSITION=DROP is assumed.</li>
|
||
<li><b>TCP_FLAGS_LOG_LEVEL - </b>Added in Version
|
||
1.3.11<br>
|
||
Determines the <a href="shorewall_logging.html">syslog
|
||
level</a> for logging packets that fail the checks enabled by the
|
||
<a href="#Interfaces">tcpflags</a> interface option.The value must
|
||
be a valid syslogd log level. If you don't want to log these packets,
|
||
set to the empty value (e.g., TCP_FLAGS_LOG_LEVEL="").<br>
|
||
</li>
|
||
<li><b>MACLIST_DISPOSITION </b>- Added in Version
|
||
1.3.10<br>
|
||
Determines the disposition of connections requests
|
||
that fail <a href="MAC_Validation.html">MAC Verification</a> and
|
||
must have the value ACCEPT (accept the connection request anyway), REJECT
|
||
(reject the connection request) or DROP (ignore the connection request).
|
||
If not set or if set to the empty value (e.g., MACLIST_DISPOSITION="")
|
||
then MACLIST_DISPOSITION=REJECT is assumed.</li>
|
||
<li><b>MACLIST_LOG_LEVEL </b>- Added in Version
|
||
1.3.10<br>
|
||
Determines the <a
|
||
href="shorewall_logging.html">syslog level</a> for logging connection
|
||
requests that fail <a href="MAC_Validation.html">MAC Verification</a>.
|
||
The value must be a valid syslogd log level. If you don't want
|
||
to log these connection requests, set to the empty value (e.g.,
|
||
MACLIST_LOG_LEVEL="").<br>
|
||
</li>
|
||
<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>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 <a href="shorewall_logging.html">syslog level</a> at which
|
||
you want the packets logged. Example: LOGNEWNOTSYN=ULOG|<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.</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></b><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>
|
||
|
||
|
||
|
||
<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>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>
|
||
LOGRATE=10/minute<br>
|
||
LOGBURST=5<br>
|
||
</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. NAT operations include:<br>
|
||
<br>
|
||
Static NAT<br>
|
||
Port Forwarding<br>
|
||
Port Redirection<br>
|
||
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>
|
||
On or on - packet forwarding
|
||
will be enabled.<br>
|
||
Off or off - packet forwarding
|
||
will be disabled.<br>
|
||
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 <a
|
||
href="shorewall_logging.html">syslog level</a>
|
||
(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> </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. 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
|
||
"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> -- 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 -- see the <a href="#Conf">RFC1918_LOG_LEVEL</a>
|
||
parameter above.</li>
|
||
|
||
|
||
|
||
|
||
</ul>
|
||
|
||
</li>
|
||
|
||
</ul>
|
||
|
||
|
||
|
||
|
||
|
||
<h2><a name="Routestopped"></a>/etc/shorewall/routestopped (Added in Version
|
||
1.3.4)</h2>
|
||
|
||
|
||
|
||
|
||
|
||
<p>This file defines the hosts that are accessible from the firewall when
|
||
the firewall is stopped. 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>
|
||
|
||
|
||
|
||
|
||
|
||
<h2><a name="Maclist"></a>/etc/shorewall/maclist (Added in Version 1.3.10)</h2>
|
||
This file is described in the <a
|
||
href="MAC_Validation.html">MAC Validation Documentation</a>.<br>
|
||
|
||
<h2><a name="ECN"></a>/etc/shorewall/ecn (Added in Version 1.4.0)</h2>
|
||
This file is described in the <a
|
||
href="ECN.html">ECN Control Documentation</a>.<br>
|
||
<br>
|
||
|
||
<p><font size="-1"> Updated 3/21/2003 - <a href="support.htm">Tom Eastep</a>
|
||
</font></p>
|
||
|
||
|
||
|
||
|
||
<p><a href="copyright.htm"><font size="2">Copyright</font> <20> <font
|
||
size="2">2001, 2002, 2003 Thomas M. Eastep.</font></a><br>
|
||
</p>
|
||
<br>
|
||
<br>
|
||
</body>
|
||
</html>
|