forked from extern/shorewall_code
4812805e77
git-svn-id: https://shorewall.svn.sourceforge.net/svnroot/shorewall/trunk@8687 fbd18981-670d-0410-9b5c-8dc0c1a9a2bb
759 lines
30 KiB
XML
759 lines
30 KiB
XML
<?xml version="1.0" encoding="UTF-8"?>
|
||
<!DOCTYPE article PUBLIC "-//OASIS//DTD DocBook XML V4.4//EN"
|
||
"http://www.oasis-open.org/docbook/xml/4.4/docbookx.dtd">
|
||
<article>
|
||
<!--$Id$-->
|
||
|
||
<articleinfo>
|
||
<title>Actions</title>
|
||
|
||
<authorgroup>
|
||
<author>
|
||
<firstname>Tom</firstname>
|
||
|
||
<surname>Eastep</surname>
|
||
</author>
|
||
</authorgroup>
|
||
|
||
<pubdate><?dbtimestamp format="Y/m/d"?></pubdate>
|
||
|
||
<copyright>
|
||
<year>2005</year>
|
||
|
||
<year>2007</year>
|
||
|
||
<year>2008</year>
|
||
|
||
<holder>Thomas M. Eastep</holder>
|
||
</copyright>
|
||
|
||
<legalnotice>
|
||
<para>Permission is granted to copy, distribute and/or modify this
|
||
document under the terms of the GNU Free Documentation License, Version
|
||
1.2 or any later version published by the Free Software Foundation; with
|
||
no Invariant Sections, with no Front-Cover, and with no Back-Cover
|
||
Texts. A copy of the license is included in the section entitled
|
||
<quote><ulink url="GnuCopyright.htm">GNU Free Documentation
|
||
License</ulink></quote>.</para>
|
||
</legalnotice>
|
||
</articleinfo>
|
||
|
||
<caution>
|
||
<para>This article applies to Shorewall 4.0 and later. If you are running
|
||
a version of Shorewall earlier than Shorewall 4.0.0 then please see the
|
||
documentation for that release.</para>
|
||
</caution>
|
||
|
||
<section id="Intro">
|
||
<title>What are Shorewall Actions?</title>
|
||
|
||
<para>Shorewall actions allow a symbolic name to be associated with a
|
||
series of one or more iptables rules. The symbolic name may appear in the
|
||
ACTION column of an <filename><ulink
|
||
url="manpages/shorewall-rules.html">/etc/shorewall/rules</ulink></filename>
|
||
file entry, in which case the traffic matching that rules file entry will
|
||
be passed to the series of iptables rules named by the action.</para>
|
||
|
||
<para>Actions can be thought of as templates. When an action is invoked in
|
||
an <filename>/etc/shorewall/rules</filename> entry, it may be qualified by
|
||
a logging specification (log level and optionally a log tag). The presence
|
||
of the log level/tag causes a modified series of rules to be generated in
|
||
which each packet/rule match within the action causes a log message to be
|
||
generated.</para>
|
||
|
||
<para>There are three types of Shorewall actions:</para>
|
||
|
||
<orderedlist>
|
||
<listitem>
|
||
<para>Built-in Actions. These actions are known by the Shorewall code
|
||
itself. They are listed in the comments at the top of the file
|
||
<filename>/usr/share/shorewall/actions.std</filename>.</para>
|
||
</listitem>
|
||
|
||
<listitem>
|
||
<para>Standard Actions. These actions are released as part of
|
||
Shorewall. They are listed in the file
|
||
<filename>/usr/share/shorewall/actions.std</filename> and are defined
|
||
in the corresponding action.* files in <filename
|
||
class="directory">/usr/share/shorewall</filename>. Each
|
||
<filename>action.*</filename> file has a comment at the beginning of
|
||
the file that describes what the action does. As an example, here is
|
||
the definition of the <firstterm>AllowSMB</firstterm> standard action
|
||
from Shorewall version 2.2.</para>
|
||
|
||
<programlisting>#
|
||
# Shorewall 2.2 /usr/share/shorewall/action.AllowSMB
|
||
#
|
||
# Allow Microsoft SMB traffic. You need to invoke this action in
|
||
# both directions.
|
||
#
|
||
######################################################################################
|
||
#TARGET SOURCE DEST PROTO DEST SOURCE RATE USER/
|
||
# PORT PORT(S) LIMIT GROUP
|
||
ACCEPT - - udp 135,445
|
||
ACCEPT - - udp 137:139
|
||
ACCEPT - - udp 1024: 137
|
||
ACCEPT - - tcp 135,139,445
|
||
#LAST LINE -- ADD YOUR ENTRIES BEFORE THIS ONE -- DO NOT REMOVE</programlisting>
|
||
|
||
<para>If you wish to modify one of the standard actions, do not modify
|
||
the definition in <filename
|
||
class="directory">/usr/share/shorewall</filename>. Rather, copy the
|
||
file to <filename class="directory">/etc/shorewall</filename> (or
|
||
somewhere else on your CONFIG_PATH) and modify the copy.</para>
|
||
|
||
<para>Standard Actions were largely replaced by <ulink
|
||
url="Macros.html">macros</ulink> in Shorewall 3.0 and later major
|
||
versions.</para>
|
||
</listitem>
|
||
|
||
<listitem>
|
||
<para>User-defined Actions. These actions are created by end-users.
|
||
They are listed in the file
|
||
<filename>/etc/shorewall/actions</filename> and are defined in
|
||
<filename>action.*</filename> files in <filename
|
||
class="directory">/etc/shorewall</filename> or in another directory
|
||
listed in your CONFIG_PATH (defined in <filename><ulink
|
||
url="manpages/shorewall.conf.html">/etc/shorewall/shorewall.conf</ulink></filename>).</para>
|
||
</listitem>
|
||
</orderedlist>
|
||
</section>
|
||
|
||
<section id="Enabling">
|
||
<title>Enabling the Use of Actions</title>
|
||
|
||
<para>In Shorewall version 3.4 and later, to make use of any of the three
|
||
types of actions you must set the USE_ACTIONS option to Yes in
|
||
<filename>/etc/shorewall/shorewall.conf</filename>.</para>
|
||
</section>
|
||
|
||
<section id="Default">
|
||
<title>Default Actions (Formerly Common Actions)</title>
|
||
|
||
<para>Shorewall allows the association of a <firstterm>default
|
||
action</firstterm> with policies. A separate default action may be
|
||
associated with ACCEPT, DROP and REJECT policies. Default actions provide
|
||
a way to invoke a set of common rules just before the policy is enforced.
|
||
Default actions accomplish two goals:</para>
|
||
|
||
<orderedlist>
|
||
<listitem>
|
||
<para>Relieve log congestion. Default actions typically include rules
|
||
to silently drop or reject traffic that would otherwise be logged when
|
||
the policy is enforced.</para>
|
||
</listitem>
|
||
|
||
<listitem>
|
||
<para>Ensure correct operation. Default actions can also avoid common
|
||
pitfalls like dropping connection requests on port TCP port 113. If
|
||
these connections are dropped (rather than rejected) then you may
|
||
encounter problems connecting to Internet services that utilize the
|
||
AUTH protocol of client authentication<footnote>
|
||
<para>AUTH is actually pretty silly on today's Internet but it's
|
||
amazing how many servers still employ it.</para>
|
||
</footnote>.</para>
|
||
</listitem>
|
||
</orderedlist>
|
||
|
||
<para>Shorewall supports default actions for the ACCEPT, REJECT, DROP,
|
||
QUEUE and NFQUEUE policies. These default actions are specified in the
|
||
<filename>/etc/shorewall/shorewall.conf</filename> file using the
|
||
ACCEPT_DEFAULT, REJECT_DEFAULT, DROP_DEFAULT, QUEUE_DEFAULT and
|
||
NFQUEUE_DEFAULT options respectively. Policies whose default is set to a
|
||
value of <quote>none</quote> have no default action.</para>
|
||
|
||
<para>In addition, the default specified in
|
||
<filename>/etc/shorewall/shorewall.conf</filename> may be overridden by
|
||
specifying a different default in the POLICY column of <filename><ulink
|
||
url="manpages/shorewall-policy.html">/etc/shorewall/policy</ulink></filename>.</para>
|
||
|
||
<warning>
|
||
<para>Entries in the DROP and REJECT default actions <emphasis
|
||
role="bold">ARE NOT THE CAUSE OF CONNECTION PROBLEMS</emphasis>.
|
||
Remember — default actions are only invoked immediately before the
|
||
packet is going to be dropped or rejected anyway!!!</para>
|
||
</warning>
|
||
</section>
|
||
|
||
<section id="Limit">
|
||
<title>Limiting Per-IP Connection Rate</title>
|
||
|
||
<para>Beginning with Shorewall 3.0.4, Shorewall has a <quote>Limit</quote>
|
||
<ulink url="Actions.html">action</ulink>. Limit is invoked with a
|
||
comma-separated list in place of a logging tag. The list has three
|
||
elements:</para>
|
||
|
||
<orderedlist>
|
||
<listitem>
|
||
<para>The name of a <quote>recent</quote> set; you select the set name
|
||
which must conform to the rules for a valid chain name. Different
|
||
rules that specify the same set name will use the same set of
|
||
counters.</para>
|
||
</listitem>
|
||
|
||
<listitem>
|
||
<para>The number of connections permitted in a specified time
|
||
period.</para>
|
||
</listitem>
|
||
|
||
<listitem>
|
||
<para>The time period, expressed in seconds.</para>
|
||
</listitem>
|
||
</orderedlist>
|
||
|
||
<para>Connections that exceed the specified rate are dropped.</para>
|
||
|
||
<para>For example, to use a recent set name of <emphasis
|
||
role="bold">SSHA</emphasis>, and to limit SSH connections to 3 per minute,
|
||
use this entry in <filename>/etc/shorewall/rules</filename>:</para>
|
||
|
||
<programlisting>#ACTION SOURCE DEST PROTO DEST PORT(S)
|
||
Limit:none:SSHA,3,60 net $FW tcp 22</programlisting>
|
||
|
||
<para>If you want dropped connections to be logged at the info level, use
|
||
this rule instead:</para>
|
||
|
||
<programlisting>#ACTION SOURCE DEST PROTO DEST PORT(S)
|
||
Limit:info:SSHA,3,60 net $FW tcp 22</programlisting>
|
||
|
||
<para>To summarize, you pass four pieces of information to the Limit
|
||
action:</para>
|
||
|
||
<itemizedlist>
|
||
<listitem>
|
||
<para>The log level. If you don't want to log, specify <quote>none</quote>.</para>
|
||
</listitem>
|
||
|
||
<listitem>
|
||
<para>The name of the recent set that you want to use
|
||
(<quote>SSHA</quote> in this example).</para>
|
||
</listitem>
|
||
|
||
<listitem>
|
||
<para>The maximum number of connections to accept (3 in this
|
||
example).</para>
|
||
</listitem>
|
||
|
||
<listitem>
|
||
<para>The number of seconds over which you are willing to accept that
|
||
many connections (60 in this example).</para>
|
||
</listitem>
|
||
</itemizedlist>
|
||
|
||
<section id="LimitImp">
|
||
<title>How Limit is Implemented</title>
|
||
|
||
<para>For those who are curious, the Limit action is implemented in
|
||
Shorewall 3.0 and Shorewall 3.2 as follows:</para>
|
||
|
||
<itemizedlist>
|
||
<listitem>
|
||
<para>The file
|
||
<filename>/usr/share/shorewall/action</filename>. Limit is
|
||
empty.</para>
|
||
</listitem>
|
||
|
||
<listitem>
|
||
<para>The file <filename>/usr/share/shorewall/Limit</filename> is as
|
||
follows:</para>
|
||
|
||
<programlisting>set -- $(separate_list $TAG)
|
||
|
||
[ $# -eq 3 ] || fatal_error "Rule must include <set name>,<max connections>,<interval> as the log tag"
|
||
|
||
run_iptables -A $CHAIN -m recent --name $1 --set
|
||
|
||
if [ -n "$LEVEL" ]; then
|
||
run_iptables -N $CHAIN%
|
||
log_rule_limit $LEVEL $CHAIN% $1 DROP "" "" -A
|
||
run_iptables -A $CHAIN% -j DROP
|
||
run_iptables -A $CHAIN -m recent --name $1 --update --seconds $3 --hitcount $(( $2 + 1 )) -j $CHAIN%
|
||
else
|
||
run_iptables -A $CHAIN -m recent --update --name $1 --seconds $3 --hitcount $(( $2 + 1 )) -j DROP
|
||
fi
|
||
|
||
run_iptables -A $CHAIN -j ACCEPT</programlisting>
|
||
</listitem>
|
||
</itemizedlist>
|
||
|
||
<para>In Shorewall 3.3, Limit is made into a built-in action; basically
|
||
that means that the above code now lives inside of Shorewall rather than
|
||
in a separate file.</para>
|
||
|
||
<para>For completeness, here's the above
|
||
<filename>/usr/share/shorewall/Limit</filename> for use with
|
||
Shorewall-perl:</para>
|
||
|
||
<programlisting>my @tag = split /,/, $tag;
|
||
|
||
fatal_error 'Limit rules must include <set name>,<max connections>,<interval> as the log tag (' . join( ':', 'Limit', $level eq '' ? 'none' : $level , $tag ) . ')'
|
||
unless @tag == 3;
|
||
|
||
my $set = $tag[0];
|
||
|
||
for ( @tag[1,2] ) {
|
||
fatal_error 'Max connections and interval in Limit rules must be numeric (' . join( ':', 'Limit', $level eq '' ? 'none' : $level, $tag ) . ')' unless /^\d+$/
|
||
}
|
||
|
||
my $count = $tag[1] + 1;
|
||
|
||
add_rule $chainref, "-m recent --name $set --set";
|
||
|
||
if ( $level ) {
|
||
my $xchainref = new_chain 'filter' , "$chainref->{name}%";
|
||
log_rule_limit $level, $xchainref, $tag[0], 'DROP', '', '', 'add', '';
|
||
add_rule $xchainref, '-j DROP';
|
||
add_rule $chainref, "-m recent --name $set --update --seconds $tag[2] --hitcount $count -j $xchainref->{name}";
|
||
} else {
|
||
add_rule $chainref, "-m recent --update --name $set --seconds $tag[2] --hitcount $count -j DROP";
|
||
}
|
||
|
||
add_rule $chainref, '-j ACCEPT';
|
||
|
||
1; </programlisting>
|
||
</section>
|
||
</section>
|
||
|
||
<section id="Defining">
|
||
<title>Defining your own Actions</title>
|
||
|
||
<para>Before defining a new action, you should evaluate whether your goal
|
||
can be best accomplished using an action or a
|
||
<firstterm>macro</firstterm>. See <ulink url="Macros.html">this
|
||
article</ulink> for details.</para>
|
||
|
||
<para>To define a new action:</para>
|
||
|
||
<orderedlist>
|
||
<listitem>
|
||
<para>Add a line to
|
||
<filename>/etc/shorewall/actions</filename> that
|
||
names your new action. Action names must be valid shell variable names
|
||
(must begin with a letter and be composed of letters, digits and
|
||
underscore characters) as well as valid Netfilter chain names. If you
|
||
intend to log from the action, the name must have a maximum of 11
|
||
characters. It is recommended that the name you select for a new
|
||
action begins with a capital letter; that way, the name won't conflict
|
||
with a Shorewall-defined chain name.</para>
|
||
|
||
<para>The name of the action may be optionally followed by a colon
|
||
(<quote>:</quote>) and ACCEPT, DROP or REJECT. When this is done, the
|
||
named action will become the <emphasis>default action</emphasis> for
|
||
policies of type ACCEPT, DROP or REJECT, respectively. The default
|
||
action is applied immediately before the policy is enforced (before
|
||
any logging is done under that policy) and is used mainly to suppress
|
||
logging of uninteresting traffic which would otherwise clog your logs.
|
||
The same policy name can appear in multiple actions; the last such
|
||
action for each policy name is the one which Shorewall will
|
||
use.</para>
|
||
|
||
<para>Shorewall includes pre-defined actions for DROP and REJECT --
|
||
see above.</para>
|
||
</listitem>
|
||
|
||
<listitem>
|
||
<para>Once you have defined your new action name (ActionName), then
|
||
copy <filename>/usr/share/shorewall/action.template</filename> to
|
||
<filename>/etc/shorewall/action.ActionName</filename> (for example, if
|
||
your new action name is <quote>Foo</quote> then copy
|
||
<filename>/usr/share/shorewall/action.template</filename> to
|
||
<filename>/etc/shorewall/action.Foo</filename>).</para>
|
||
</listitem>
|
||
|
||
<listitem>
|
||
<para>Now modify the new file to define the new action.</para>
|
||
</listitem>
|
||
</orderedlist>
|
||
|
||
<para>Columns in the <filename>action.template</filename> file are as
|
||
follows:</para>
|
||
|
||
<itemizedlist>
|
||
<listitem>
|
||
<para>TARGET - Must be ACCEPT, DROP, REJECT, LOG, CONTINUE, QUEUE or
|
||
<<emphasis>action</emphasis>> where
|
||
<<emphasis>action</emphasis>> is a previously-defined action
|
||
(that is, it must precede the action being defined in this file in
|
||
your <filename>/etc/shorewall/actions</filename> file). These actions
|
||
have the same meaning as they do in the
|
||
<filename>/etc/shorewall/rules</filename> file (CONTINUE terminates
|
||
processing of the current action and returns to the point where that
|
||
action was invoked). The TARGET may optionally be followed by a colon
|
||
(<quote>:</quote>) and a syslog log level (e.g, REJECT:info or
|
||
ACCEPT:debugging). This causes the packet to be logged at the
|
||
specified level. You may also specify ULOG (must be in upper case) as
|
||
a log level. This will log to the ULOG target for routing to a
|
||
separate log through use of ulogd (<ulink
|
||
url="http://www.netfilter.org/projects/ulogd/index.html">http://www.netfilter.org/projects/ulogd/index.html</ulink>).</para>
|
||
|
||
<para>You may also use a <ulink url="Macros.html">macro</ulink> in
|
||
your action provided that the macro's expansion only results in the
|
||
ACTIONs ACCEPT, DROP, REJECT, LOG, CONTINUE, or QUEUE. See
|
||
<filename>/usr/share/shorewall/Drop</filename> for an example of an
|
||
action that users macros extensively.</para>
|
||
</listitem>
|
||
|
||
<listitem>
|
||
<para>SOURCE - Source hosts to which the rule applies. A
|
||
comma-separated list of subnets and/or hosts. Hosts may be specified
|
||
by IP or MAC address; MAC addresses must begin with <quote>~</quote>
|
||
and must use <quote>-</quote> as a separator.</para>
|
||
|
||
<para>Alternatively, clients may be specified by interface name. For
|
||
example, eth1 specifies a client that communicates with the firewall
|
||
system through eth1. This may be optionally followed by another colon
|
||
(<quote>:</quote>) and an IP/MAC/subnet address as described above
|
||
(e.g., eth1:192.168.1.5).</para>
|
||
</listitem>
|
||
|
||
<listitem>
|
||
<para>DEST - Location of Server. Same as above with the exception that
|
||
MAC addresses are not allowed.</para>
|
||
|
||
<para>Unlike in the SOURCE column, you may specify a range of up to
|
||
256 IP addresses using the syntax <<emphasis>first
|
||
ip</emphasis>>-<<emphasis>last ip</emphasis>>.</para>
|
||
</listitem>
|
||
|
||
<listitem>
|
||
<para>PROTO - Protocol - Must be <quote>tcp</quote>,
|
||
<quote>udp</quote>, <quote>icmp</quote>, a protocol number, or
|
||
<quote>all</quote>.</para>
|
||
</listitem>
|
||
|
||
<listitem>
|
||
<para>DEST PORT(S) - Destination Ports. A comma-separated list of Port
|
||
names (from <filename>/etc/services</filename>), port numbers or port
|
||
ranges; if the protocol is <quote>icmp</quote>, this column is
|
||
interpreted as the destination icmp-type(s).</para>
|
||
|
||
<para>A port range is expressed as <<emphasis>low
|
||
port</emphasis>>:<<emphasis>high port</emphasis>>.</para>
|
||
|
||
<para>This column is ignored if PROTO = <quote>all</quote>, but must be
|
||
entered if any of the following fields are supplied. In that case, it
|
||
is suggested that this field contain <quote>-</quote>.</para>
|
||
|
||
<para>If your kernel contains multi-port match support, then only a
|
||
single Netfilter rule will be generated if in this list and in the
|
||
CLIENT PORT(S) list below:</para>
|
||
|
||
<orderedlist>
|
||
<listitem>
|
||
<para>There are 15 or less ports listed.</para>
|
||
</listitem>
|
||
|
||
<listitem>
|
||
<para>No port ranges are included.</para>
|
||
</listitem>
|
||
</orderedlist>
|
||
|
||
<para>Otherwise, a separate rule will be generated for each
|
||
port.</para>
|
||
</listitem>
|
||
|
||
<listitem>
|
||
<para>SOURCE PORT(S) - Port(s) used by the client. If omitted, any
|
||
source port is acceptable. Specified as a comma-separated list of port
|
||
names, port numbers or port ranges.</para>
|
||
|
||
<para>If you don't want to restrict client ports but need to specify
|
||
any of the subsequent fields, then place <quote>-</quote> in this
|
||
column.</para>
|
||
|
||
<para>If your kernel contains multi-port match support, then only a
|
||
single Netfilter rule will be generated if in this list and in the
|
||
DEST PORT(S) list above:</para>
|
||
|
||
<orderedlist>
|
||
<listitem>
|
||
<para>There are 15 or less ports listed.</para>
|
||
</listitem>
|
||
|
||
<listitem>
|
||
<para>No port ranges are included.</para>
|
||
</listitem>
|
||
</orderedlist>
|
||
|
||
<para>Otherwise, a separate rule will be generated for each
|
||
port.</para>
|
||
</listitem>
|
||
|
||
<listitem>
|
||
<para>RATE LIMIT - You may rate-limit the rule by placing a value in
|
||
this column:</para>
|
||
|
||
<para><programlisting> <<emphasis>rate</emphasis>>/<<emphasis>interval</emphasis>>[:<<emphasis>burst</emphasis>>]</programlisting>where
|
||
<<emphasis>rate</emphasis>> is the number of connections per
|
||
<<emphasis>interval</emphasis>> (<quote>sec</quote> or
|
||
<quote>min</quote>) and <<emphasis>burst</emphasis>> is the
|
||
largest burst permitted. If no <<emphasis>burst</emphasis>> is
|
||
given, a value of 5 is assumed. There may be no whitespace embedded in
|
||
the specification.</para>
|
||
|
||
<para><programlisting> Example: 10/sec:20</programlisting></para>
|
||
</listitem>
|
||
|
||
<listitem>
|
||
<para>USER/GROUP - For output rules (those with the firewall as their
|
||
source), you may control connections based on the effective UID and/or
|
||
GID of the process requesting the connection. This column can contain
|
||
any of the following:</para>
|
||
|
||
<simplelist>
|
||
<member>[!]<<emphasis>user number</emphasis>>[:]</member>
|
||
|
||
<member>[!]<<emphasis>user name</emphasis>>[:]</member>
|
||
|
||
<member>[!]:<<emphasis>group number</emphasis>></member>
|
||
|
||
<member>[!]:<<emphasis>group name</emphasis>></member>
|
||
|
||
<member>[!]<<emphasis>user
|
||
number</emphasis>>:<<emphasis>group
|
||
number</emphasis>></member>
|
||
|
||
<member>[!]<<emphasis>user
|
||
name</emphasis>>:<<emphasis>group
|
||
number</emphasis>></member>
|
||
|
||
<member>[!]<<emphasis>user
|
||
inumber</emphasis>>:<<emphasis>group
|
||
name</emphasis>></member>
|
||
|
||
<member>[!]<<emphasis>user
|
||
name</emphasis>>:<<emphasis>group name</emphasis>></member>
|
||
|
||
<member>[!]+<<emphasis>program name</emphasis>> (Note: support
|
||
for this form was removed from Netfilter in kernel version
|
||
2.6.14).</member>
|
||
</simplelist>
|
||
</listitem>
|
||
|
||
<listitem>
|
||
<para>MARK (Added in Shorewall 3.4.4)</para>
|
||
|
||
<para><simplelist>
|
||
<member>[!]<<emphasis>value</emphasis>>[/<<emphasis>mask</emphasis>>][:C]</member>
|
||
</simplelist></para>
|
||
|
||
<para>Defines a test on the existing packet or connection mark. The
|
||
rule will match only if the test returns true.</para>
|
||
|
||
<para>If you don’t want to define a test but need to specify anything
|
||
in the subsequent columns, place a <quote>-</quote> in this field.<simplelist>
|
||
<member>! — Inverts the test (not equal)</member>
|
||
|
||
<member><<emphasis>value</emphasis>> — Value of the packet
|
||
or connection mark.</member>
|
||
|
||
<member><<emphasis>mask</emphasis>> —A mask to be applied to
|
||
the mark before testing.</member>
|
||
|
||
<member>:C — Designates a connection mark. If omitted, the packet
|
||
mark’s value is tested. This option is only supported by
|
||
Shorewall-perl</member>
|
||
</simplelist></para>
|
||
</listitem>
|
||
</itemizedlist>
|
||
|
||
<para>Omitted column entries should be entered using a dash
|
||
(<quote>-</quote>).</para>
|
||
|
||
<para>Example:</para>
|
||
|
||
<para><filename>/etc/shorewall/actions</filename>:</para>
|
||
|
||
<para><programlisting> #ACTION COMMENT (place '# ' below the 'C' in comment followed by
|
||
# v a comment describing the action)
|
||
LogAndAccept # LOG and ACCEPT a connection</programlisting><emphasis
|
||
role="bold">Note:</emphasis> If your
|
||
<filename>/etc/shorewall/actions</filename> file doesn't have an
|
||
indication where to place the comment, put the <quote>#</quote> in column
|
||
21.</para>
|
||
|
||
<para><phrase><filename>/etc/shorewall/action.LogAndAccept</filename></phrase><programlisting> LOG:info
|
||
ACCEPT</programlisting></para>
|
||
|
||
<para>Placing a comment on the line causes the comment to appear in the
|
||
output of the <command>shorewall show actions</command> command.</para>
|
||
|
||
<para>To use your action, in <filename>/etc/shorewall/rules</filename> you
|
||
might do something like:</para>
|
||
|
||
<programlisting>#ACTION SOURCE DEST PROTO DEST PORT(S)
|
||
LogAndAccept loc $FW tcp 22</programlisting>
|
||
</section>
|
||
|
||
<section id="Logging">
|
||
<title>Actions and Logging</title>
|
||
|
||
<para>Specifying a log level in a rule that specifies a user-defined or
|
||
Shorewall-defined action will cause each rule in the action to be logged
|
||
with the specified level (and tag).</para>
|
||
|
||
<para>The extent to which logging of action rules occur is governed by the
|
||
following:</para>
|
||
|
||
<orderedlist>
|
||
<listitem>
|
||
<para>When you invoke an action and specify a log level, only those
|
||
rules in the action that have no log level will be changed to log at
|
||
the level specified at the action invocation.</para>
|
||
|
||
<para>Example:</para>
|
||
|
||
<para>/etc/shorewall/action.foo</para>
|
||
|
||
<programlisting>#TARGET SOURCE DEST PROTO DEST PORT(S)
|
||
ACCEPT - - tcp 22
|
||
bar:info</programlisting>
|
||
|
||
<para>/etc/shorewall/rules:</para>
|
||
|
||
<programlisting>#ACTION SOURCE DEST PROTO DEST PORT(S)
|
||
foo:debug $FW net</programlisting>
|
||
|
||
<para>Logging in the invoke <quote>foo</quote> action will be as if foo
|
||
had been defined as:</para>
|
||
|
||
<programlisting>#TARGET SOURCE DEST PROTO DEST PORT(S)
|
||
ACCEPT:debug - - tcp 22
|
||
bar:info</programlisting>
|
||
</listitem>
|
||
|
||
<listitem>
|
||
<para>If you follow the log level with <quote>!</quote> then logging
|
||
will be set at that level for all rules recursively invoked by the
|
||
action.</para>
|
||
|
||
<para>Example:</para>
|
||
|
||
<para>/etc/shorewall/action.foo</para>
|
||
|
||
<programlisting>#TARGET SOURCE DEST PROTO DEST PORT(S)
|
||
ACCEPT - - tcp 22
|
||
bar:info</programlisting>
|
||
|
||
<para>/etc/shorewall/rules:</para>
|
||
|
||
<programlisting>#ACTION SOURCE DEST PROTO DEST PORT(S)
|
||
foo:debug! $FW net</programlisting>
|
||
|
||
<para>Logging in the invoke <quote>foo</quote> action will be as if foo
|
||
had been defined as:</para>
|
||
|
||
<programlisting>#TARGET SOURCE DEST PROTO DEST PORT(S)
|
||
ACCEPT:debug - - tcp 22
|
||
bar:debug</programlisting>
|
||
</listitem>
|
||
</orderedlist>
|
||
|
||
<para>If you define an action <quote>acton</quote> and you have an
|
||
<filename>/etc/shorewall/acton</filename> script, when that script is
|
||
invoked, the following three variables will be set for use by the
|
||
script:</para>
|
||
|
||
<itemizedlist>
|
||
<listitem>
|
||
<para>$CHAIN = the name of the chain where your rules are to be
|
||
placed. When logging is used on an action invocation, Shorewall
|
||
creates a chain with a slightly different name from the action
|
||
itself.</para>
|
||
</listitem>
|
||
|
||
<listitem>
|
||
<para>$LEVEL = Log level. If empty, no logging was specified.</para>
|
||
</listitem>
|
||
|
||
<listitem>
|
||
<para>$TAG = Log Tag.</para>
|
||
</listitem>
|
||
</itemizedlist>
|
||
|
||
<para>Example:</para>
|
||
|
||
<para><filename>/etc/shorewall/rules</filename>:</para>
|
||
|
||
<programlisting>#ACTION SOURCE DEST
|
||
acton:info:test $FW net</programlisting>
|
||
|
||
<para>Your <filename>/etc/shorewall/acton</filename> file will be run
|
||
with:</para>
|
||
|
||
<itemizedlist>
|
||
<listitem>
|
||
<para>$CHAIN=<quote>%acton1</quote></para>
|
||
</listitem>
|
||
|
||
<listitem>
|
||
<para>$LEVEL=<quote>info</quote></para>
|
||
</listitem>
|
||
|
||
<listitem>
|
||
<para>$TAG=<quote>test</quote></para>
|
||
</listitem>
|
||
</itemizedlist>
|
||
|
||
<para>Shorewall-perl sets lexical variables as follows:</para>
|
||
|
||
<itemizedlist>
|
||
<listitem>
|
||
<para><emphasis role="bold">$chainref</emphasis> is a reference to the
|
||
chain-table entry for the chain where your rules are to be
|
||
placed.</para>
|
||
</listitem>
|
||
|
||
<listitem>
|
||
<para><emphasis role="bold">$level</emphasis> is the log level. If
|
||
false, no logging was specified.</para>
|
||
</listitem>
|
||
|
||
<listitem>
|
||
<para><emphasis role="bold">$tag</emphasis> is the log tag.</para>
|
||
</listitem>
|
||
</itemizedlist>
|
||
|
||
<para>For an example of how to use these variables in both Shorewall-shell
|
||
and Shorewall-perl, see <ulink url="PortKnocking.html">this
|
||
article</ulink>.</para>
|
||
</section>
|
||
|
||
<section id="Extension">
|
||
<title>Creating an Action using an Extension Script</title>
|
||
|
||
<para>There may be cases where you wish to create a chain with rules that
|
||
can't be constructed using the tools defined in the
|
||
<filename>action.template</filename>. In that case, you can use an <ulink
|
||
url="shorewall_extension_scripts.htm">extension script</ulink>.<note>
|
||
<para>If you actually need an action to drop broadcast packets, use
|
||
the <command>dropBcast</command> standard action rather than create
|
||
one like this.</para>
|
||
</note></para>
|
||
|
||
<example id="Example">
|
||
<title>An action to drop all broadcast packets</title>
|
||
|
||
<para>/etc/shorewall/actions<programlisting>DropBcasts</programlisting></para>
|
||
|
||
<para>/etc/shorewall/action.DropBcasts<programlisting># This file is empty</programlisting>When
|
||
using Shorewall-shell:</para>
|
||
|
||
<para><blockquote>
|
||
<para>/etc/shorewall/DropBcasts<programlisting>[ -n "$LEVEL" ] && log_rule_limit $LEVEL $CHAIN DropBcasts DROP "" "$TAG" -A
|
||
run_iptables -A DropBcasts -m pkttype --pkttype broadcast -j DROP</programlisting></para>
|
||
</blockquote>When using Shorewall-Perl:<blockquote>
|
||
<para>/etc/shorewall/DropBcasts<programlisting>use Shorewall::Chains;
|
||
|
||
log_rule_limit( $level, $chainref, 'DropBcasts', 'DROP', '', $tag, 'add', '' ) if $level ne '';
|
||
add_rule( $chainref, '-m pkttype --pkttype broadcast -j DROP' );
|
||
|
||
1;</programlisting></para>
|
||
</blockquote></para>
|
||
</example>
|
||
|
||
<para>For a richer example, see <ulink url="PortKnocking.html">this
|
||
article</ulink>.</para>
|
||
</section>
|
||
</article>
|