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Fix SVN link in PortKnocking article and copy Limit Action section to Actions article.

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git-svn-id: https://shorewall.svn.sourceforge.net/svnroot/shorewall/trunk@7071 fbd18981-670d-0410-9b5c-8dc0c1a9a2bb
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el_cubano 2007-08-06 04:19:54 +00:00
parent 81b071dc7c
commit 0d384f7575
2 changed files with 149 additions and 2 deletions
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146
docs/Actions.xml
View File

@ -188,6 +188,152 @@ Reject:REJECT #Default Action for REJECT policy</programlisting>
</warning>
</section>
<section id="Limit">
<title>Limiting Per-IP Connection Rate</title>
<important>
<para>Debian users. This feature is broken in the Debian version 3.0.7
of Shorewall (and possibly in other versions). The file
<filename>/usr/share/shorewall/Limit</filename> was inadvertently dropped
from the .deb. That file may be obtained from <ulink
url="http://shorewall.svn.sourceforge.net/viewvc/*checkout*/shorewall/tags/3.0.7/Shorewall/Limit?revision=3888">Shorewall
SVN</ulink> and installed manually.</para>
</important>
<para>Beginning with Shorewall 3.0.4, Shorewall has a 'Limit' <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 'recent' 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 limiting SSH 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 "none".</para>
</listitem>
<listitem>
<para>The name of the recent set that you want to use ("SSHA" 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 &lt;set name&gt;,&lt;max connections&gt;,&lt;interval&gt; 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 &lt;set name&gt;,&lt;max connections&gt;,&lt;interval&gt; 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-&gt;{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-&gt;{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>

5
docs/PortKnocking.xml
View File

@ -176,7 +176,8 @@ SSHKnock net loc:192.168.1.5 tcp 22 -
of Shorewall (and possibly in other versions). The file
<filename>/usr/share/shorewall/Limit</filename> was inadvertently
dropped from the .deb. That file may be obtained from <ulink
url="???">Shorewall SVN</ulink> and installed manually.</para>
url="http://shorewall.svn.sourceforge.net/viewvc/*checkout*/shorewall/tags/3.0.7/Shorewall/Limit?revision=3888">Shorewall
SVN</ulink> and installed manually.</para>
</important>
<para>Beginning with Shorewall 3.0.4, Shorewall has a 'Limit' <ulink
@ -312,4 +313,4 @@ add_rule $chainref, '-j ACCEPT';
1; </programlisting>
</section>
</section>
</article>
</article>