forked from extern/shorewall_code
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git-svn-id: https://shorewall.svn.sourceforge.net/svnroot/shorewall/trunk@2698 fbd18981-670d-0410-9b5c-8dc0c1a9a2bb
407 lines
16 KiB
XML
407 lines
16 KiB
XML
<?xml version="1.0" encoding="UTF-8"?>
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<!DOCTYPE article PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
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"http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
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<article lang="en" status="">
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<!--$Id$-->
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<articleinfo>
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<title>Macros</title>
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<authorgroup>
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<author>
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<firstname>Tom</firstname>
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<surname>Eastep</surname>
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</author>
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<author>
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<firstname>Cristian</firstname>
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<surname>Rodríguez</surname>
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</author>
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</authorgroup>
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<pubdate>2005-09-12</pubdate>
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<copyright>
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<year>2005</year>
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<holder>Thomas M. Eastep</holder>
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</copyright>
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<legalnotice>
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<para>Permission is granted to copy, distribute and/or modify this
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document under the terms of the GNU Free Documentation License, Version
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1.2 or any later version published by the Free Software Foundation; with
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no Invariant Sections, with no Front-Cover, and with no Back-Cover
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Texts. A copy of the license is included in the section entitled
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<quote><ulink url="GnuCopyright.htm">GNU Free Documentation
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License</ulink></quote>.</para>
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</legalnotice>
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</articleinfo>
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<caution>
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<para><emphasis role="bold">This article applies to Shorewall 3.0 and
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later. If you are running a version of Shorewall earlier than Shorewall
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3.0.0 then please see the documentation for that
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release.</emphasis></para>
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</caution>
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<section>
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<title>What are Shorewall Macros?</title>
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<para>Shorewall macros allow a symbolic name to be associated with a
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series of one or more iptables rules. The symbolic name may appear in the
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ACTION column of an <filename><ulink
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url="Documentation.htm#Rules">/etc/shorewall/rules</ulink></filename> file
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entry and in the TARGET column of an action in which case, the traffic
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matching that rules file entry will be passed to the series of iptables
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rules named by the macro.</para>
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<para>Macros can be thought of as templates. When a macro is invoked in an
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<filename>/etc/shorewall/rules</filename> entry, it may be qualified by a
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logging specification (log level and optionally a log tag). The presence
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of the log level/tag causes a modified series of rules to be generated in
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which each packet/rule match within the macro causes a log message to be
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generated.</para>
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<para>There are two types of Shorewall macros:</para>
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<orderedlist>
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<listitem>
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<para>Standard Macros. These macros are released as part of Shorewall.
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They are defined in macros.* files in <filename
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class="directory">/usr/share/shorewall</filename>. Each
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<filename>macros.*</filename> file has a comment at the beginning of
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the file that describes what the macro does. As an example, here is
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the definition of the <firstterm>SMB</firstterm> standard
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macro.</para>
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<programlisting>#
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# Shorewall 2.2 /usr/share/shorewall/macro.AllowSMB
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#
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# Allow Microsoft SMB traffic. You need to invoke this macro in
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# both directions.
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#
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######################################################################################
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#TARGET SOURCE DEST PROTO DEST SOURCE RATE USER/
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# PORT PORT(S) LIMIT GROUP
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PARAM - - udp 135,445
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PARAM - - udp 137:139
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PARAM - - udp 1024: 137
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PARAM - - tcp 135,139,445
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#LAST LINE -- ADD YOUR ENTRIES BEFORE THIS ONE -- DO NOT REMOVE</programlisting>
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<para>If you wish to modify one of the standard macros, do not modify
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the definition in /usr/share/shorewall. Rather, copy the file to
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<filename class="directory">/etc/shorewall</filename> (or somewhere
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else on your CONFIG_PATH) and modify the copy.</para>
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</listitem>
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<listitem>
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<para>User-defined Macros. These macros are created by end-users. They
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are defined in macros.* files in /etc/shorewall or in another
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directory listed in your CONFIG_PATH (defined in <ulink
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url="Documentation.htm#Conf">/etc/shorewall/shorewall.conf</ulink>).</para>
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</listitem>
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</orderedlist>
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</section>
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<section>
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<title>Defining your own Macros</title>
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<para>To define a new macro:</para>
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<orderedlist>
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<listitem>
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<para>Macro names must be valid shell variable names ((must begin with
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a letter and be composed of letters, digits and underscore characters)
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as well as valid Netfilter chain names.</para>
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</listitem>
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<listitem>
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<para>Copy /usr/share/shorewall/macro.template to
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<filename>/etc/shorewall/macro.ActionName</filename> (for example, if
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your new macro name is <quote>Foo</quote> then copy
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<filename>/usr/share/shorewall/macro.template</filename> to
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<filename>/etc/shorewall/macro.Foo</filename>).</para>
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</listitem>
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<listitem>
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<para>Now modify the new file to define the new macro.</para>
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</listitem>
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</orderedlist>
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<para>Columns in the macro.template file are as follows:</para>
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<itemizedlist>
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<listitem>
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<para>ACTION - ACCEPT, DROP, REJECT, DNAT, DNAT-, REDIRECT, CONTINUE,
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LOG, QUEUE, PARAM or an action name.</para>
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<simplelist>
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<member>ACCEPT - allow the connection request</member>
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<member>ACCEPT+ - like ACCEPT but also excludes the connection from
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any subsequent DNAT[-] or REDIRECT[-] rules.</member>
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<member>NONAT - Excludes the connection from any subsequent DNAT[-]
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or REDIRECT[-] rules but doesn't generate a rule to accept the
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traffic.</member>
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<member>DROP - ignore the request</member>
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<member>REJECT - disallow the request and return an icmp unreachable
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or an RST packet.</member>
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<member>DNAT - Forward the request to another address (and
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optionally another port).</member>
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<member>DNAT- - Advanced users only. Like DNAT but only generates
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the DNAT iptables rule and not the companion ACCEPT rule.</member>
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<member>SAME - Similar to DNAT except that the port may not be
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remapped and when multiple server addresses are listed, all requests
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from a given remote system go to the same server.</member>
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<member>SAME- - Advanced users only. Like SAME but only generates
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the SAME iptables rule and not the companion ACCEPT rule.</member>
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<member>REDIRECT - Redirect the request to a local port on the
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firewall.</member>
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<member>REDIRECT- - Advanced users only. Like REDIRECT but only
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generates the REDIRECT iptables rule and not the companion ACCEPT
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rule.</member>
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<member>CONTINUE - (For experts only). Do not process any of the
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following rules for this (source zone,destination zone). If The
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source and/or destination If the address falls into a zone defined
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later in /etc/shorewall/zones, this connection request will be
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passed to the rules defined for that (those) zone(s).</member>
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<member>LOG - Simply log the packet and continue.</member>
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<member>QUEUE - Queue the packet to a user-space application such as
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ftwall (http://p2pwall.sf.net).</member>
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</simplelist>
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<para>The ACTION may optionally be followed by ":" and a syslog log
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level (e.g, REJECT:info or DNAT:debug). This causes the packet to be
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logged at the specified level.</para>
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<para>(<ulink
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url="http://www.gnumonks.org/projects/ulogd">http://www.gnumonks.org/projects/ulogd</ulink>).</para>
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</listitem>
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<listitem>
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<para>SOURCE - Source hosts to which the rule applies. A
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comma-separated list of subnets and/or hosts. Hosts may be specified
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by IP or MAC address; mac addresses must begin with <quote>~</quote>
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and must use <quote>-</quote> as a separator.</para>
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<para>Alternatively, clients may be specified by interface name. For
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example, eth1 specifies a client that communicates with the firewall
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system through eth1. This may be optionally followed by another colon
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(<quote>:</quote>) and an IP/MAC/subnet address as described above
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(e.g. eth1:192.168.1.5).</para>
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</listitem>
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<listitem>
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<para>DEST - Location of Server. Same as above with the exception that
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MAC addresses are not allowed.</para>
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<para>Unlike in the SOURCE column, you may specify a range of up to
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256 IP addresses using the syntax <<emphasis>first
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ip</emphasis>>-<<emphasis>last ip</emphasis>>.</para>
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</listitem>
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<listitem>
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<para>PROTO - Protocol - Must be <quote>tcp</quote>,
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<quote>udp</quote>, <quote>icmp</quote>, a number, or
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<quote>all</quote>.</para>
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</listitem>
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<listitem>
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<para>DEST PORT(S) - Destination Ports. A comma-separated list of Port
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names (from <filename>/etc/services</filename>), port numbers or port
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ranges; if the protocol is <quote>icmp</quote>, this column is
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interpreted as the destination icmp-type(s).</para>
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<para>A port range is expressed as <<emphasis>low
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port</emphasis>>:<<emphasis>high port</emphasis>>.</para>
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<para>This column is ignored if PROTOCOL = all but must be entered if
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any of the following fields are supplied. In that case, it is
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suggested that this field contain <quote>-</quote>.</para>
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<para>If your kernel contains multi-port match support, then only a
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single Netfilter rule will be generated if in this list and in the
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CLIENT PORT(S) list below:</para>
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<orderedlist>
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<listitem>
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<para>There are 15 or less ports listed.</para>
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</listitem>
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<listitem>
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<para>No port ranges are included.</para>
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</listitem>
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</orderedlist>
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<para>Otherwise, a separate rule will be generated for each
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port.</para>
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</listitem>
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<listitem>
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<para>SOURCE PORT(S) - Port(s) used by the client. If omitted, any
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source port is acceptable. Specified as a comma-separated list of port
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names, port numbers or port ranges.</para>
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<para>If you don't want to restrict client ports but need to specify
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an ADDRESS in the next column, then place "-" in this column.</para>
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<para>If your kernel contains multi-port match support, then only a
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single Netfilter rule will be generated if in this list and in the
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DEST PORT(S) list above:</para>
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<orderedlist>
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<listitem>
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<para>There are 15 or less ports listed.</para>
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</listitem>
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<listitem>
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<para>No port ranges are included.</para>
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</listitem>
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</orderedlist>
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<para>Otherwise, a separate rule will be generated for each
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port.</para>
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</listitem>
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<listitem>
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<para>RATE LIMIT - You may rate-limit the rule by placing a value in
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this column:</para>
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<para><programlisting> <<emphasis>rate</emphasis>>/<<emphasis>interval</emphasis>>[:<<emphasis>burst</emphasis>>]</programlisting>where
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<<emphasis>rate</emphasis>> is the number of connections per
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<<emphasis>interval</emphasis>> (<quote>sec</quote> or
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<quote>min</quote>) and <<emphasis>burst</emphasis>> is the
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largest burst permitted. If no <<emphasis>burst</emphasis>> is
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given, a value of 5 is assumed. There may be no whitespace embedded in
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the specification.</para>
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<para><programlisting> Example: 10/sec:20</programlisting></para>
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</listitem>
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<listitem>
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<para>USER/GROUP - For output rules (those with the firewall as their
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source), you may control connections based on the effective UID and/or
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GID of the process requesting the connection. This column can contain
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any of the following:</para>
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<simplelist>
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<member>[!]<<emphasis>user number</emphasis>>[:]</member>
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<member>[!]<<emphasis>user name</emphasis>>[:]</member>
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<member>[!]:<<emphasis>group number</emphasis>></member>
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<member>[!]:<<emphasis>group name</emphasis>></member>
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<member>[!]<<emphasis>user
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number</emphasis>>:<<emphasis>group
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number</emphasis>></member>
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<member>[!]<<emphasis>user
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name</emphasis>>:<<emphasis>group
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number</emphasis>></member>
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<member>[!]<<emphasis>user
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inumber</emphasis>>:<<emphasis>group
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name</emphasis>></member>
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<member>[!]<<emphasis>user
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name</emphasis>>:<<emphasis>group name</emphasis>></member>
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</simplelist>
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</listitem>
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</itemizedlist>
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<para>Omitted column entries should be entered using a dash ("-:).</para>
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<para>Example:</para>
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<para><phrase><filename>/etc/shorewall/macro.LogAndAccept</filename></phrase><programlisting> LOG:info
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ACCEPT</programlisting></para>
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<para>To use your macro, in <filename>/etc/shorewall/rules</filename> you
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might do something like:</para>
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<programlisting>#ACTION SOURCE DEST PROTO DEST PORT(S)
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LogAndAccept loc $FW tcp 22</programlisting>
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</section>
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<section>
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<title>Macros and Logging</title>
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<para>Specifying a log level in a rule that invokes a user- or
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Shorewall-defined action will cause each rule in the macro to be logged
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with the specified level (and tag).</para>
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<para>The extent to which logging of macro rules occur is governed by the
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following:</para>
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<orderedlist>
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<listitem>
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<para>When you invoke a macro and specify a log level, only those
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rules in the macro that have no log level will be changed to log at
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the level specified at the action invocation.</para>
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<para>Example:</para>
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<para>/etc/shorewall/macro.foo</para>
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<programlisting>#ACTION SOURCE DEST PROTO DEST PORT(S)
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ACCEPT - - tcp 22
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bar:info</programlisting>
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<para>/etc/shorewall/rules:</para>
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<programlisting>#ACTION SOURCE DEST PROTO DEST PORT(S)
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foo:debug $FW net</programlisting>
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<para>Logging in the invoked 'foo' macro will be as if foo had been
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defined as:</para>
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<programlisting>#ACTION SOURCE DEST PROTO DEST PORT(S)
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ACCEPT:debug - - tcp 22
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bar:info</programlisting>
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</listitem>
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<listitem>
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<para>If you follow the log level with "!" then logging will be at
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that level for all rules recursively invoked by the macro.</para>
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<para>Example:</para>
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<para>/etc/shorewall/macro.foo</para>
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<programlisting>#ACTION SOURCE DEST PROTO DEST PORT(S)
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ACCEPT - - tcp 22
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bar:info</programlisting>
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<para>/etc/shorewall/rules:</para>
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<programlisting>#ACTION SOURCE DEST PROTO DEST PORT(S)
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foo:debug! $FW net</programlisting>
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<para>Logging in the invoked 'foo' macro will be as if foo had been
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defined as:</para>
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<programlisting>#ACTION SOURCE DEST PROTO DEST PORT(S)
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ACCEPT:debug - - tcp 22
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bar:debug</programlisting>
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</listitem>
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</orderedlist>
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</section>
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</article> |