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shorewall_code/Shorewall-docs/traffic_shaping.htm
teastep 8377f70bc7 Shorewall 1.4.1 
git-svn-id: https://shorewall.svn.sourceforge.net/svnroot/shorewall/trunk@518 fbd18981-670d-0410-9b5c-8dc0c1a9a2bb
2003-03-22 00:25:40 +00:00

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<title>Traffic Shaping</title>
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<h1 align="center"><font color="#ffffff">Traffic Shaping/Control</font></h1>
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<p align="left">Shorewall has limited support for traffic shaping/control.
In order to use traffic shaping under Shorewall, it is essential that
you get a copy of the <a href="http://ds9a.nl/lartc">Linux Advanced Routing
and Shaping HOWTO</a>, version 0.3.0 or later. It is also necessary
to be running Linux Kernel 2.4.18 or later.</p>
<p align="left">Shorewall traffic shaping support consists of the following:</p>
<ul>
<li>A new <b>TC_ENABLED</b> parameter in /etc/shorewall.conf.
Traffic Shaping also requires that you enable packet mangling.</li>
<li>A new <b>CLEAR_TC </b>parameter in /etc/shorewall.conf (Added
in Shorewall 1.3.13). When Traffic Shaping is enabled (TC_ENABLED=Yes),
the setting of this variable determines whether Shorewall clears the traffic
shaping configuration during Shorewall [re]start and Shorewall stop. <br>
</li>
<li><b>/etc/shorewall/tcrules</b> - A file where you can
specify firewall marking of packets. The firewall mark value may
be used to classify packets for traffic shaping/control.<br>
</li>
<li><b>/etc/shorewall/tcstart </b>- A user-supplied file
that is sourced by Shorewall during "shorewall start" and which
you can use to define your traffic shaping disciplines and classes.
I have provided a <a
href="ftp://ftp.shorewall.net/pub/shorewall/cbq">sample</a> that does
table-driven CBQ shaping but if you read the traffic shaping sections
of the HOWTO mentioned above, you can probably code your own
faster than you can learn how to use my sample. I personally use
<a href="http://luxik.cdi.cz/%7Edevik/qos/htb/">HTB</a> (see below).
HTB support may eventually become an integral part of Shorewall
since HTB is a lot simpler and better-documented than CBQ. As of
2.4.20, HTB is a standard part of the kernel but iproute2 must be patched
in order to use it.<br>
<br>
In tcstart, when you want to run the 'tc' utility, use
the run_tc function supplied by shorewall if you want tc errors
to stop the firewall.<br>
<br>
You can generally use off-the-shelf traffic shaping scripts by
simply copying them to /etc/shorewall/tcstart. I use <a
href="http://lartc.org/wondershaper/">The Wonder Shaper</a> (HTB version)
that way (i.e., I just copied wshaper.htb to /etc/shorewall/tcstart and
modified it according to the Wonder Shaper README). <b>WARNING: </b>If
you use use Masquerading or SNAT (i.e., you only have one external IP address)
then listing internal hosts in the NOPRIOHOSTSRC variable in the wshaper[.htb]
script won't work. Traffic shaping occurs after SNAT has already been applied
so when traffic shaping happens, all outbound traffic will have as a source
address the IP addresss of your firewall's external interface.<br>
</li>
<li><b>/etc/shorewall/tcclear</b> - A user-supplied file
that is sourced by Shorewall when it is clearing traffic shaping.
This file is normally not required as Shorewall's method of clearing
qdisc and filter definitions is pretty general.</li>
</ul>
Shorewall allows you to start traffic shaping when Shorewall itself
starts or it allows you to bring up traffic shaping when you bring up
your interfaces.<br>
<br>
To start traffic shaping when Shorewall starts:<br>
<ol>
<li>Set TC_ENABLED=Yes and CLEAR_TC=Yes</li>
<li>Supply an /etc/shorewall/tcstart script to configure your traffic
shaping rules.</li>
<li>Optionally supply an /etc/shorewall/tcclear script to stop traffic
shaping. That is usually unnecessary.</li>
<li>If your tcstart script uses the 'fwmark' classifier, you can
mark packets using entries in /etc/shorewall/tcrules.</li>
</ol>
To start traffic shaping when you bring up your network interfaces,
you will have to arrange for your traffic shaping configuration script
to be run at that time. How you do that is distribution dependent and will
not be covered here. You then should:<br>
<ol>
<li>Set TC_ENABLED=Yes and CLEAR_TC=No</li>
<li>Do not supply /etc/shorewall/tcstart or /etc/shorewall/tcclear
scripts.</li>
<li value="4">If your tcstart script uses the 'fwmark' classifier,
you can mark packets using entries in /etc/shorewall/tcrules.</li>
</ol>
<h3 align="left">Kernel Configuration</h3>
<p align="left">This screen shot show how I've configured QoS in my Kernel:</p>
<p align="center"><img border="0" src="images/QoS.png" width="590"
height="764">
</p>
<h3 align="left"><a name="tcrules"></a>/etc/shorewall/tcrules</h3>
<p align="left">The fwmark classifier provides a convenient way to classify
packets for traffic shaping. The /etc/shorewall/tcrules file provides
a means for specifying these marks in a tabular fashion.<br>
</p>
<p align="left">Normally, packet marking occurs in the PREROUTING chain before
any address rewriting takes place. This makes it impossible to mark inbound
packets based on their destination address when SNAT or Masquerading are
being used. Beginning with Shorewall 1.3.12, you can cause packet marking
to occur in the FORWARD chain by using the MARK_IN_FORWARD_CHAIN option
in <a href="Documentation.htm#Conf">shorewall.conf</a>.<br>
</p>
<p align="left">Columns in the file are as follows:</p>
<ul>
<li>MARK - Specifies the mark value is to be assigned
in case of a match. This is an integer in the range 1-255. Beginning
with Shorewall version 1.3.14, this value may be optionally followed by ":"
and either 'F' or 'P' to designate that the marking will occur in the FORWARD
or PREROUTING chains respectively. If this additional specification is omitted,
the chain used to mark packets will be determined by the setting of the
MARK_IN_FORWARD_CHAIN option in <a href="Documentation.htm#Conf">shorewall.conf</a>.<br>
<br>
Example - 5<br>
</li>
<li>SOURCE - The source of the packet. If the packet originates
on the firewall, place "fw" in this column. Otherwise, this is
a comma-separated list of interface names, IP addresses, MAC addresses
in <a href="Documentation.htm#MAC">Shorewall Format</a> and/or Subnets.<br>
<br>
Examples<br>
<20><><EFBFBD> eth0<br>
<20><><EFBFBD> 192.168.2.4,192.168.1.0/24<br>
</li>
<li>DEST -- Destination of the packet. Comma-separated
list of IP addresses and/or subnets.<br>
</li>
<li>PROTO - Protocol - Must be the name of a protocol
from /etc/protocol, a number or "all"<br>
</li>
<li>PORT(S) - Destination Ports. A comma-separated list
of Port names (from /etc/services), port numbers or port ranges
(e.g., 21:22); if the protocol is "icmp", this column is interpreted
as the destination icmp type(s).<br>
</li>
<li>CLIENT PORT(S) - (Optional) Port(s) used by the client.
If omitted, any source port is acceptable. Specified as a comma-separate
list of port names, port numbers or port ranges.</li>
</ul>
<p align="left">Example 1 - All packets arriving on eth1 should be marked
with 1. All packets arriving on eth2 and eth3 should be marked with
2. All packets originating on the firewall itself should be marked
with 3.</p>
<table border="2" cellpadding="2" style="border-collapse: collapse;">
<tbody>
<tr>
<td><b>MARK</b></td>
<td><b>SOURCE</b></td>
<td><b>DEST</b></td>
<td><b>PROTO</b></td>
<td><b>PORT(S)</b></td>
<td><b>CLIENT PORT(S)</b></td>
</tr>
<tr>
<td>1</td>
<td>eth1</td>
<td>0.0.0.0/0</td>
<td>all</td>
<td><EFBFBD></td>
<td><EFBFBD></td>
</tr>
<tr>
<td>2</td>
<td>eth2</td>
<td>0.0.0.0/0</td>
<td>all</td>
<td><EFBFBD></td>
<td><EFBFBD></td>
</tr>
<tr>
<td valign="top">2<br>
</td>
<td valign="top">eth3<br>
</td>
<td valign="top">0.0.0.0/0<br>
</td>
<td valign="top">all<br>
</td>
<td valign="top"><br>
</td>
<td valign="top"><br>
</td>
</tr>
<tr>
<td>3</td>
<td>fw</td>
<td>0.0.0.0/0</td>
<td>all</td>
<td><EFBFBD></td>
<td><EFBFBD></td>
</tr>
</tbody>
</table>
<p align="left">Example 2 - All GRE (protocol 47) packets not originating
on the firewall and destined for 155.186.235.151 should be marked
with 12.</p>
<table border="2" cellpadding="2" style="border-collapse: collapse;">
<tbody>
<tr>
<td><b>MARK</b></td>
<td><b>SOURCE</b></td>
<td><b>DEST</b></td>
<td><b>PROTO</b></td>
<td><b>PORT(S)</b></td>
<td><b>CLIENT PORT(S)</b></td>
</tr>
<tr>
<td>12</td>
<td>0.0.0.0/0</td>
<td>155.186.235.151</td>
<td>47</td>
<td><EFBFBD></td>
<td><EFBFBD></td>
</tr>
</tbody>
</table>
<p align="left">Example 3 - All SSH packets originating in 192.168.1.0/24
and destined for 155.186.235.151 should be marked with 22.</p>
<table border="2" cellpadding="2" style="border-collapse: collapse;">
<tbody>
<tr>
<td><b>MARK</b></td>
<td><b>SOURCE</b></td>
<td><b>DEST</b></td>
<td><b>PROTO</b></td>
<td><b>PORT(S)</b></td>
<td><b>CLIENT PORT(S)</b></td>
</tr>
<tr>
<td>22</td>
<td>192.168.1.0/24</td>
<td>155.186.235.151</td>
<td>tcp</td>
<td>22</td>
<td><EFBFBD></td>
</tr>
</tbody>
</table>
<h3>My Setup<br>
</h3>
<p>While I am currently using the HTB version of <a
href="http://lartc.org/wondershaper/">The Wonder Shaper</a> (I just copied
wshaper.htb to <b>/etc/shorewall/tcstart</b> and modified it as shown
in the Wondershaper README), I have also run with the following set of
hand-crafted rules in my <b>/etc/shorewall/tcstart</b> file:<br>
</p>
<blockquote>
<pre>run_tc qdisc add dev eth0 root handle 1: htb default 30<br><br>run_tc class add dev eth0 parent 1: classid 1:1 htb rate 384kbit burst 15k<br><br>echo "<22><> Added Top Level Class -- rate 384kbit"</pre>
<pre>run_tc class add dev eth0 parent 1:1 classid 1:10 htb rate 140kbit ceil 384kbit burst 15k prio 1<br>run_tc class add dev eth0 parent 1:1 classid 1:20 htb rate 224kbit ceil 384kbit burst 15k prio 0<br>run_tc class add dev eth0 parent 1:1 classid 1:30 htb rate 20kbit<69> ceil 384kbit burst 15k quantum 1500 prio 1</pre>
<pre>echo "<22><> Added Second Level Classes -- rates 140kbit, 224kbit, 20kbit"</pre>
<pre>run_tc qdisc add dev eth0 parent 1:10 pfifo limit 5<br>run_tc qdisc add dev eth0 parent 1:20 pfifo limit 10<br>run_tc qdisc add dev eth0 parent 1:30 pfifo limit 5</pre>
<pre>echo "<22><> Enabled PFIFO on Second Level Classes"</pre>
<pre>run_tc filter add dev eth0 protocol ip parent 1:0 prio 1 handle 1 fw classid 1:10<br>run_tc filter add dev eth0 protocol ip parent 1:0 prio 0 handle 2 fw classid 1:20<br>run_tc filter add dev eth0 protocol ip parent 1:0 prio 1 handle 3 fw classid 1:30</pre>
<pre>echo "<22><> Defined fwmark filters"<br></pre>
</blockquote>
<p>My tcrules file that went with this tcstart file is shown in Example 1
above. You can look at <a href="myfiles.htm">my configuration</a> to
see why I wanted shaping of this type.<br>
</p>
<ol>
<li>I wanted to allow up to 140kbits/second for traffic outbound
from my DMZ (note that the ceiling is set to 384kbit so outbound DMZ
traffic can use all available bandwidth if there is no traffic from the
local systems or from my laptop or firewall).</li>
<li>My laptop and local systems could use up to 224kbits/second.</li>
<li>My firewall could use up to 20kbits/second.</li>
</ol>
You see <a href="myfiles.htm">the rest of my Shorewall configuration</a>
to see how this fit in. <br>
<p><font size="2">Last Updated 3/19/2003 - <a href="support.htm">Tom Eastep</a></font></p>
<p><font face="Trebuchet MS"><a href="copyright.htm"><font size="2">Copyright</font>
<20> <font size="2">2001, 2002, 2003 Thomas M. Eastep.</font></a></font><br>
</p>
<br>
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