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shorewall_code/Shorewall-docs/traffic_shaping.htm
teastep c2ccd7fd3d Shorewall 1.4.8 
git-svn-id: https://shorewall.svn.sourceforge.net/svnroot/shorewall/trunk@800 fbd18981-670d-0410-9b5c-8dc0c1a9a2bb
2003-12-02 23:51:46 +00:00

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<title>Traffic Shaping</title>
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<body>
<h1 style="text-align: center;">Traffic Shaping/Control<br>
</h1>
<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>
&nbsp;&nbsp;&nbsp; eth0<br>
&nbsp;&nbsp;&nbsp; 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>&nbsp;</td>
<td>&nbsp;</td>
</tr>
<tr>
<td>2</td>
<td>eth2</td>
<td>0.0.0.0/0</td>
<td>all</td>
<td>&nbsp;</td>
<td>&nbsp;</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>&nbsp;</td>
<td>&nbsp;</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>&nbsp;</td>
<td>&nbsp;</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>&nbsp;</td>
</tr>
</tbody>
</table>
<h3>My Current Setup<br>
</h3>
<p>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).<span style="font-weight: bold;"> </span>WonderShaper
DOES NOT USE THE
/etc/shorewall/tcrules file. While I currently have entries in
/etc/shorewall/tcrules, I do so for <a
href="Shorewall_Squid_Usage.html">policy routing for Squid</a> and not
for Traffic Shaping.</p>
<h3>My Old Setup<br>
</h3>
<p>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 "&nbsp;&nbsp; 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&nbsp; ceil 384kbit burst 15k quantum 1500 prio 1</pre>
<pre>echo "&nbsp;&nbsp; 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 "&nbsp;&nbsp; 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 "&nbsp;&nbsp; Defined fwmark filters"<br></pre>
</blockquote>
<p>My tcrules file that went with this tcstart file is shown in Example
1 above. When I was using these rules:<br>
</p>
<ol>
<li>I wanted to allow up to 140kbits/second for traffic outbound from
my DMZ (eth1 -- 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 (which at that time connected via eth3) and local
systems (eth2) could use up to 224kbits/second.</li>
<li>My firewall could use up to 20kbits/second.</li>
</ol>
Once www.shorewall.net was moved off-site, I no longer needed these
shaping rules and The Wonder Shaper does all that I now require.<br>
<p><font size="2">Last Updated 10/21/2003 - <a href="support.htm">Tom
Eastep</a></font></p>
<p><font face="Trebuchet MS"><a href="copyright.htm"><font size="2">Copyright</font>
<EFBFBD> <font size="2">2001, 2002, 2003 Thomas M. Eastep.</font></a></font><br>
</p>
<br>
<br>
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