Traffic Shaping/ControlTomEastepArneBernin2001-2008Thomas M. Eastep2005Arne Bernin & Thomas M. EastepPermission 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
GNU Free Documentation
License.Traffic shaping is complex and the Shorewall community is not well
equiped to answer traffic shaping questions. So if you are the type of
person who needs "insert tab A into slot B" instructions for everything
that you do, then please don't try to implement traffic shaping using
Shorewall. You will just frustrate yourself and we won't be able to help
you.Said another way, reading just Shorewall documentation is not going
to give you enough background to use this material.At a minimum, you will need to refer to at least the following
additional information:The LARTC HOWTO: http://www.lartc.orgThe HTB User's Guide: http://luxik.cdi.cz/~devik/qos/htb/manual/userg.htmSome of the documents listed at http://www.netfilter.org/documentation/index.html#documentation-howto.
The tutorial by Oskar Andreasson is particularly good.The output of man iptablesIntroductionStarting with Version 2.5.5, Shorewall has builtin support for
traffic shaping and control. Before this version, the support was quite
limited. You were able to use your own tcstart script (and you still are),
but besides the tcrules file it was not possible to define classes or
queueing discplines inside the Shorewall config files.The support for traffic shaping and control still does not cover all
options available (and especially all algorithms that can be used to queue
traffic) in the Linux kernel but it should fit most needs. If you are
using your own script for traffic control and you still want to use it in
the future, you will find information on how to do this, later in this document. But for this to work,
you will also need to enable traffic shaping in the kernel and Shorewall
as covered by the next sections.Linux traffic shaping and controlThis section gives a brief introduction of how controlling traffic
with the linux kernel works. Although this might be enough for configuring
it in the Shorewall configuration files, we strongly recommend that you
take a deeper look into the Linux
Advanced Routing and Shaping HOWTO. At the time of writing this,
the current version is 1.0.0.Since kernel 2.2 Linux has extensive support for controlling
traffic. You can define different algorithms that are used to queue the
traffic before it leaves an interface. The standard one is called pfifo
and is (as the name suggests) of the type First In First out. This means,
that it does not shape anything, if you have a connection that eats up all
your bandwidth, this qeueing algorithm will not stop it from doing
so.For Shorewall traffic shaping we use two algorithms, one is called
HTB (Hierarchical Token Bucket) and SFQ (Stochastic Fairness Queuing). SFQ
is easy to explain: it just tries to track your connections (tcp or udp
streams) and balances the traffic between them. This normally works well.
HTB allows you to define a set of classes, and you can put the traffic you
want into these classes. You can define minimum and maximum bandwitdh
settings for those classes and order them hierachically (the less
priorized classes only get bandwitdth if the more important have what they
need). Shorewall builtin traffic shaping allows you to define these
classes (and their bandwidth limits), and it uses SFQ inside these classes
to make sure, that different data streams are handled equally.If you are running Shorewall-shell or if you
are running Shorewall-perl 4.1.5 or earlier:
You can only shape outgoing traffic. The
reason for this is simple, the packets were already received by your
network card before you can decide what to do with them. So
the only choice would be to drop them which normally makes no sense
(since you received the packet already, it went through the possible
bottleneck (the incoming connection). The next possible bottleneck
might come if the packet leaves on another interface, so this will be
the place where queuing might occur. So, defining queues for incoming
packets is not very useful, you just want to have it forwarded to the
outgoing interface as fast as possible.There is one exception, though. Limiting incoming traffic to a
value a bit slower than your actual line speed will avoid queueing on
the other end of that connection. This is mostly useful if you don't
have access to traffic control on the other side and if this other
side has a faster network connection than you do (the line speed
between the systems is the bottleneck, e.g. a DSL or Cable Modem
connection to your provider's router, the router itself is normally
connected to a much faster backbone). So, if you drop packets that are
coming in too fast, the underlying protocol might recognize this and
slow down the connection. TCP has a builtin mechanism for this, UDP
has not (but the protocol over UDP might recognize it , if there is
any).The reason why queing is bad in these cases is, that you might
have packets which need to be priorized over others, e.g. VoIP or ssh.
For this type of connections it is important that packets arrive in a
certain amount of time. For others like http downloads, it does not
really matter if it takes a few seconds more.If you have a large queue on the other side and the router there
does not care about QoS or the QoS bits are not set properly, your
important packets will go into the same queue as your less
timecritical download packets which will result in a large
delay.
If you are running Shorewall-perl 4.1.6 or
later:
You can shape incoming traffic through use of an
Intermediate Frame Block (IFB) device. See below. But beware:
using an IFB can result in queues building up both at your ISPs router
and at your own.
You shape and control outgoing traffic by assigning the traffic to
classes. Each class is associated with exactly one
network interface and has a number of attributes:PRIORITY - Used to give preference to one class over another
when selecting a packet to send. The priority is a numeric value with
1 being the highest priority, 2 being the next highest, and so
on.RATE - The minimum bandwidth this class should get, when the
traffic load rises. Classes with a higher priority (lower PRIORITY
value) are served even if there are others that have a guaranteed
bandwith but have a lower priority (higher PRIORITY value).CEIL - The maximum bandwidth the class is allowed to use when
the link is idle.MARK - Netfilter has a facility for
marking packets. Packet marks have a numeric
value which is limited in Shorewall to the values 1-255. You assign
packet marks to different types of traffic using entries in the
/etc/shorewall/tcrules file.One class for each interface must be designated as the
default class. This is the class to which unmarked
traffic (packets to which you have not assigned a mark value in
/etc/shorewall/tcrules) is assigned.Netfilter also supports a mark value on each connection. You can
assign connection mark values in
/etc/shorewall/tcrules, you can copy the current
packet's mark to the connection mark (SAVE), or you can copy the
connection mark value to the current packet's mark (RESTORE).Linux Kernel ConfigurationYou will need at least kernel 2.4.18 for this to work, please take a
look at the following screenshot for what settings you need to enable. For
builtin support, you need the HTB scheduler, the Ingress scheduler, the
PRIO pseudoscheduler and SFQ queue. The other scheduler or queue
algorithms are not needed.This screen shot shows how I configured QoS in a 2.6.16
Kernel:And here's my recommendation for a 2.6.21 kernel:Enable TC support in ShorewallYou need this support whether you use the builtin support or whether
you provide your own tcstart script.To enable the builtin traffic shaping and control in Shorewall, you
have to do the following:Set TC_ENABLED to "Internal" in
/etc/shorewall/shorewall.conf. Setting TC_ENABLED=Yes causes Shorewall
to look for an external tcstart file (See a
later section for details).Setting CLEAR_TC parameter in
/etc/shorewall/shorewall.conf to Yes will clear the traffic shaping
configuration during Shorewall [re]start and Shorewall stop. This is
normally what you want when using the builtin support (and also if you
use your own tcstart script)The other steps that follow depend on whether you use your own
script or the builtin solution. They will be explained in the
following sections.Using builtin traffic shaping/controlShorewall's builtin traffic shaping feature provides a thin layer on
top of the ingress qdesc, HTB and SFQ. That translation layer allows you
to:Define HTB classes using Shorewall-style column-oriented
configuration files.Integrate the reloading of your traffic shaping configuration
with the reloading of your packet-filtering and marking
configuration.Assign traffic to HTB classes by TOS value.Assign outgoing TCP ACK packets to an HTB class.Assign traffic to HTB classes based on packet mark value.Shorewall's builtin traffic shaping feature is limited to ten (10)
devices.Those few features are really all that builtin traffic
shaping/control provides; consequently, you need to understand HTB and
Linux traffic shaping as well as Netfilter packet marking in order to use
the facility. Again, please see the links at top of this article.For defining bandwidths (for either devices or classes) please use
kbit or kbps(for Kilobytes per second) and make sure there is NO space between the number and the unit (it is
100kbit not 100 kbit). Using mbit, mbps
or a raw number (which means bytes) could be used, but note that only
integer numbers are supported (0.5 is not
valid).To properly configure the settings for your devices you might need
to find out the real up- and downstream rates you have. This is especially
the case, if you are using a DSL connection or one of another type that do
not have a guaranteed bandwidth. Don't trust the values your provider
tells you for this; especially measuring the real download speed is
important! There are several online tools that help you find out; search
for "dsl speed test" on google (For Germany you can use arcor speed
check). Be sure to choose a test located near you./etc/shorewall/tcdevicesThis file allows you to define the incoming and outgoing bandwidth
for the devices you want traffic shaping to be enabled. That means, if
you want to use traffic shaping for a device, you have to define it
here.Columns in the file are as follows:INTERFACE - Name of interface. Each interface may be listed
only once in this file. You may NOT specify the name of an alias
(e.g., eth0:0) here; see FAQ #18.
You man NOT specify wildcards here, e.g. if you have multiple ppp
interfaces, you need to put them all in here! With Shorewall
versions prior to 3.0.8 and 3.2.0 Beta 8, the device named in this
column must exist at the time that Shorewall is started, restarted
or refreshed. Beginning with Shorewall 3.0.8 and 3.2.0 Beta 8,
Shorewall will determine if the device exists and will only
configure the device if it does exist. If it doesn't exist, the
following warning is issued:WARNING: Device <device name> not
found -- traffic-shaping configuration skippedShorewall assigns a sequential interface
number to each interface (the first entry in
/etc/shorewall/tcdevices is interface 1, the
second is interface 2 and so on) Beginning with Shorewall-perl
4.1.6, you can explicitly specify the interface number by prefixing
the interface name with the number and a colon (":"). Example:
1:eth0.IN-BANDWIDTH - The incoming Bandwidth of that interface.
Please note that when you use this column, you are not traffic
shaping incoming traffic, as the traffic is already received before
you could do so. This Column allows you to define the maximum
traffic allowed for this interface in total, if the rate is
exceeded, the packets are dropped. You want this mainly if you have
a DSL or Cable Connection to avoid queuing at your providers side.
If you don't want any traffic to be dropped set this to a value
faster than your interface maximum rate (or to 0 (zero), if you are
running Shorewall 3.2.6 or later).To determine the optimum value for this setting, we recommend
that you start by setting it significantly below your measured
download bandwidth (20% or so). While downloading, measure the
ping response time from the firewall to the
upstream router as you gradually increase the setting.The optimal
setting is at the point beyond which the ping
time increases sharply as you increase the setting.OUT-BANDWIDTH - Specifiy the outgoing bandwidth of that
interface. This is the maximum speed your connection can handle. It
is also the speed you can refer as "full" if you define the tc
classes. Outgoing traffic above this rate will be dropped.OPTIONS (Added in Shorewall-perl 4.1.4) — A comma-separated
list of options from the following list:classifyIf specified, classification of traffic into the various
classes is done by CLASSIFY entries in
/etc/shorewall/tcrules or by entries in
/etc/shorewall/tcfilters. No MARK value
will be associated with classes on this interface.REDIRECTED INTERFACES (Added in Shorewall-perl 4.1.6) —
Entries are appropriate in this column only if the device in the
INTERFACE column names a Intermediate Frame
Block (IFB). It lists the physical interfaces that will have
their input shaped using classes defined on the IFB. Neither the IFB
nor any of the interfaces listed in this column may have an
IN-BANDWIDTH specified. You may specify zero (0) or a dash ("-:) in
the IN-BANDWIDTH column.IFB devices automatically get the classify option.Suppose you are using PPP over Ethernet (DSL) and ppp0 is the
interface for this. The device has an outgoing bandwidth of 500kbit
and an incoming bandwidth of 6000kbit#INTERFACE IN-BANDWITH OUT-BANDWIDTH
ppp0 6000kbit 500kbit/etc/shorewall/tcclassesThis file allows you to define the actual classes that are used to
split the outgoing traffic.INTERFACE - Name of interface. Users of Shorewall-perl 4.1.6
or later may also specify the interface number. Must match the name
(or number) of an interface with an entry in
/etc/shorewall/tcdevices. If the interface has
the classify option in
/etc/shorewall/tcdevices, then the interface
name or number must be followed by a colon and a class
number. Examples: eth0:1, 4:9. Class numbers must be
unique for a given interface.MARK - The mark value which is an integer in the range 1-255.
You define these marks in the tcrules file, marking the traffic you
want to go into the queueing classes defined in here. You can use
the same marks for different Interfaces. You must specify "-' in
this column if the device specified in the INTERFACE column has the
classify option in
/etc/shorewall/tcdevices.RATE - The minimum bandwidth this class should get, when the
traffic load rises. Please note that first the classes which equal
or a lesser priority value are served even if there are others that
have a guaranteed bandwith but a lower priority. If the sum of the RATEs for all classes assigned to an
INTERFACE exceed that interfaces's OUT-BANDWIDTH, then the
OUT-BANDWIDTH limit will not be honored.CEIL - The maximum bandwidth this class is allowed to use when
the link is idle. Useful if you have traffic which can get full
speed when more important services (e.g. interactive like ssh) are
not used. You can use the value "full" in here for setting the
maximum bandwidth to the defined output bandwidth of that
interface.PRIORITY - you have to define a priority for the class.
packets in a class with a higher priority (=lesser value) are
handled before less priorized onces. You can just define the mark
value here also, if you are increasing the mark values with lesser
priority.OPTIONS - A comma-separated list of options including the
following:default - this is the default class for that interface
where all traffic should go, that is not classified
otherwise.defining default for exactly one class per interface is
mandatory!tos-<tosname> - this lets you define a filter for
the given <tosname> which lets you define a value of the
Type Of Service bits in the ip package which causes the package
to go in this class. Please note, that this filter overrides all
mark settings, so if you define a tos filter for a class all
traffic having that mark will go in it regardless of the mark on
the package. You can use the following for this option:
tos-minimize-delay (16) tos-maximize-throughput (8)
tos-maximize-reliability (4) tos-minimize-cost (2)
tos-normal-service (0)Each of this options is only valid for one class per interface.tcp-ack - if defined causes an tc filter to be created
that puts all tcp ack packets on that interface that have an
size of <=64 Bytes to go in this class. This is useful for
speeding up downloads. Please note that the size of the ack
packets is limited to 64 bytes as some applications (p2p for
example) use to make every package an ack package which would
cause them all into here. We want only packets WITHOUT payload
to match, so the size limit. Bigger packets just take their
normal way into the classes.This option is only valid for class per interface./etc/shorewall/tcrulesUnlike rules in the shorewall-rules(5) file,
evaluation of rules in this file will continue after a match. So the
final mark for each packet will be the one assigned by the LAST tcrule
that matches.The fwmark classifier provides a convenient way to classify
packets for traffic shaping. The /etc/shorewall/tcrules
file is used for specifying these marks in a tabular fashion. For an
in-depth look at the packet marking facility in Netfilter/Shorewall,
please see this article.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. You can cause packet marking to occur in the FORWARD chain
by using the MARK_IN_FORWARD_CHAIN option in shorewall.conf.Columns in the file are as follows:MARK or CLASSIFY - MARK specifies the mark value is to be
assigned in case of a match. This is an integer in the range 1-255.
This value may be optionally followed by : and either
F, P or "T" to designate that the
marking will occur in the FORWARD, PREROUTING or POSTROUTING chains
respectively. If this additional specification is omitted, the chain
used to mark packets will be determined as follows:If the SOURCE is
$FW[:<address>], then the rule is
inserted in the OUTPUT chain.Otherwise, the chain is determined by the setting of the
MARK_IN_FORWARD_CHAIN option in shorewall.conf.The "T" qualifier was added in Shorewall version 3.3.6 and
is not available in earlier versions.Normally, the mark is applied to the packet. If you follow the
mark value with ":" and "C", then the mark is applied to the
connection. "C" can be combined with "F", "P" or "T" to designate
that the connection should be marked in a particular chain (e.g.,
"CF", "CP", "CT").There are additional special values available:RESTORE[/mask] --
restore the packet's mark from the connection's mark using the
supplied mask if any. Your kernel and iptables must include
CONNMARK support.As above, may be followed by :P, :F
or :T.SAVE[/mask] -- save
the packet's mark to the connection's mark using the supplied
mask if any. Your kernel and iptables must include CONNMARK
support.As above, may be followed by :P, :F
or :T.CONTINUE Don't process
any more marking rules in the table.As above, may be followed by :P, :F
or :T.COMMENT (Added in
Shorewall version 3.3.3) -- the rest of the line will be
attached as a comment to the Netfilter rule(s) generated by the
following entries. The comment will appear delimited by "/* ...
*/" in the output of shorewall show
mangleTo stop the comment from being attached to further rules,
simply include COMMENT on a line by itself.To use CLASSIFY, your kernel and iptables must include
CLASSIFY target support. In that case, this column contains a
classification (classid) of the form <major>:<minor>
where <major> and <minor> are integers. Corresponds to
the 'class' specification in these traffic shaping modules:atmcbqdsmarkpfifo_fasthtbprioWith Shorewall versions prior to 3.2.3, classify rules are
always placed in the POSTROUTING chain. Beginning with Shorewall
3.2.3, classification occurs in the POSTROUTING chain except when the SOURCE contains
$FW[:<address>] in which case, the
classify action takes place in the OUTPUT chain. When used with the
builtin traffic shaper, the <major> class is the interface
number and the <minor> class is either a) the MARK value of
the class preceded by the number "1" (MARK value 1 is <minor>
class 11, MARK value 22 is <minor> class 122, and so on) or b)
The class number (if the classify
option was specified in for the interface
/etc/shorewall/interfaces)SOURCE - Source of the packet. A comma-separated list of
interface names, IP addresses, MAC addresses and/or subnets for
packets being routed through a common path. List elements may also
consist of an interface name followed by ":" and an address (e.g.,
eth1:192.168.1.0/24). For example, all packets for connections
masqueraded to eth0 from other interfaces can be matched in a single
rule with several alternative SOURCE criteria. However, a connection
whose packets gets to eth0 in a different way, e.g., direct from the
firewall itself, needs a different rule.Accordingly, use $FW in its own separate rule for packets
originating on the firewall. In such a rule, the MARK column may NOT
specify either ":P" or ":F" because marking for firewall-originated
packets always occurs in the OUTPUT chain.MAC addresses must be prefixed with "~" and use "-" as a
separator.Example: ~00-A0-C9-15-39-78DEST - Destination of the packet. Comma separated list of IP
addresses and/or subnets. If your kernel and iptables include
iprange match support, IP address ranges are also allowed. List
elements may also consist of an interface name followed by ":" and
an address (e.g., eth1:192.168.1.0/24). If the MARK column
specificies a classification of the form <major>:<minor>
then this column may also contain an interface name.PROTO - Protocol - Must be "tcp", "udp", "icmp", "ipp2p",
"ipp2p:udp", "ipp2p:all" a number, or "all". "ipp2p" requires ipp2p
match support in your kernel and iptables.PORT(S) - Destination Ports. A comma-separated list of Port
names (from /etc/services), port numbers or port ranges; if the
protocol is "icmp", this column is interpreted as the destination
icmp-type(s).If the protocol is ipp2p, this column is interpreted as an
ipp2p option without the leading "--" (example "bit" for
bit-torrent). If no PORT is given, "ipp2p" is assumed.This column is ignored if PROTOCOL = all but must be entered
if any of the following field is supplied. In that case, it is
suggested that this field contain "-"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.USER/GROUP (Added in Shorewall version 1.4.10) - (Optional)
This column may only be non-empty if the SOURCE is the firewall
itself. When this column is non-empty, the rule applies only if the
program generating the output is running under the effective user
and/or group. It may contain :[!][<user name or number>]:[<group name or
number>][+<program name>]The colon is optionnal when specifying only a user.Examples:joe #program must be run by joe
:kids #program must be run by a member of the 'kids' group
!:kids #program must not be run by a member of the 'kids' group
+upnpd #program named upnpd (This feature was removed from Netfilter in kernel version 2.6.14).TEST - Defines a test on the existing packet or connection
mark. The rule will match only if the test returns true. Tests have
the format [!]<value>[/<mask>][:C]Where:! Inverts the test (not equal)<value> Value of the packet or connection
mark.<mask> A mask to be applied to the mark before
testing:C Designates a connection mark. If omitted, the packet
mark's value is tested.LENGTH (Optional, added in Shorewall version 3.2.0) Packet
Length - This field, if present, allows you to match the length of a
packet against a specific value or range of values. A range is
specified in the form <min>:<max> where either
<min> or <max> (but not both) may be omitted. If
<min> is omitted, then 0 is assumed; if <max> is
omitted, than any packet that is <min> or longer will
match.You must have iptables length support for this to work. If you
let it empy or place an "-" here, no length match will be
done.Examples: 1024, 64:1500, :100TOS (Optional, added in Shorewall version 3.2.0 Beta 6) Type
of Service. Either a standard name, or a numeric value to
match.
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.#MARK SOURCE DESTINATION PROTOCOL PORT(S)
1 eth1 0.0.0.0/0 all
2 eth2 0.0.0.0/0 all
2 eth3 0.0.0.0/0 all
3 $FW 0.0.0.0/0 allAll GRE (protocol 47) packets not originating on the firewall
and destined for 155.186.235.151 should be marked with 12.#MARK SOURCE DESTINATION PROTOCOL PORT(S)
12 0.0.0.0/0 155.182.235.151 47All SSH request packets originating in 192.168.1.0/24 and
destined for 155.186.235.151 should be marked with 22.#MARK SOURCE DESTINATION PROTOCOL PORT(S)
22 192.168.1.0/24 155.182.235.151 tcp 22All SSH packets packets going out of the first device in in
/etc/shorewall/tcdevices should be assigned to the class with mark
value 10.#MARK SOURCE DESTINATION PROTOCOL PORT(S) CLIENT
# PORT(S)
1:110 0.0.0.0/0 0.0.0.0/0 tcp 22
1:110 0.0.0.0/0 0.0.0.0/0 tcp - 22Mark all ICMP echo traffic with packet mark 1. Mark all peer to
peer traffic with packet mark 4.This is a little more complex than otherwise expected. Since the
ipp2p module is unable to determine all packets in a connection are
P2P packets, we mark the entire connection as P2P if any of the
packets are determined to match. We assume packet/connection mark 0 to
means unclassified.#MARK SOURCE DESTINATION PROTOCOL PORT(S) CLIENT USER/ TEST
# PORT(S) GROUP
1 0.0.0.0/0 0.0.0.0/0 icmp echo-request
1 0.0.0.0/0 0.0.0.0/0 icmp echo-reply
RESTORE 0.0.0.0/0 0.0.0.0/0 all - - - 0
CONTINUE 0.0.0.0/0 0.0.0.0/0 all - - - !0
4 0.0.0.0/0 0.0.0.0/0 ipp2p:all
SAVE 0.0.0.0/0 0.0.0.0/0 all - - - !0The last four rules can be translated as:
"If a packet hasn't been classifed (packet mark is 0), copy
the connection mark to the packet mark. If the packet mark is set,
we're done. If the packet is P2P, set the packet mark to 4. If the
packet mark has been set, save it to the connection mark."
ppp devicesIf you use ppp/pppoe/pppoa) to connect to your internet provider
and you use traffic shaping you need to restart shorewall traffic
shaping. The reason for this is, that if the ppp connection gets
restarted (and it usally does this at least daily), all
tc filters/qdiscs related to that interface are
deleted.The easiest way to achieve this, is just to restart shorewall once
the link is up. To achieve this add a small executable script
to/etc/ppp/ip-up.d.#! /bin/sh
/sbin/shorewall refreshReal life examplesConfiguration to replace WondershaperYou are able to fully replace the wondershaper script by using
the buitin traffic control.You can find example configuration files at
"http://www1.shorewall.net/pub/shorewall/Samples/tc4shorewall/.
Please note that they are just examples and need to be adjusted to
work for you. In this example it is assumed that your interface for
you internet connection is ppp0 (for DSL), if you use another
connection type, you have to change it. You also need to change the
settings in the tcdevices.wondershaper file to reflect your line
speed. The relevant lines of the config files follow here. Please note
that this is just a 1:1 replacement doing exactly what wondershaper
should do. You are free to change it...tcdevices file#INTERFACE IN-BANDWITH OUT-BANDWIDTH
ppp0 5000kbit 500kbittcclasses file#INTERFACE MARK RATE CEIL PRIORITY OPTIONS
ppp0 1 5*full/10 full 1 tcp-ack,tos-minimize-delay
ppp0 2 3*full/10 9*full/10 2 default
ppp0 3 2*full/10 8*full/10 2tcrules file#MARK SOURCE DEST PROTO PORT(S) CLIENT USER
# PORT(S)
1:F 0.0.0.0/0 0.0.0.0/0 icmp echo-request
1:F 0.0.0.0/0 0.0.0.0/0 icmp echo-reply
# mark traffic which should have a lower priority with a 3:
# mldonkey
3 0.0.0.0/0 0.0.0.0/0 udp - 4666Wondershaper allows you to define a set of hosts and/or ports
you want to classify as low priority. To achieve this , you have to
add these hosts to tcrules and set the mark to 3 (true if you use
the example configuration files).Setting hosts to low prioritylets assume the following settings from your old wondershaper
script (don't assume these example values are really useful, they
are only used for demonstrating ;-):
# low priority OUTGOING traffic - you can leave this blank if you want
# low priority source netmasks
NOPRIOHOSTSRC="192.168.1.128/25 192.168.3.28"
# low priority destination netmasks
NOPRIOHOSTDST=60.0.0.0/24
# low priority source ports
NOPRIOPORTSRC="6662 6663"
# low priority destination ports
NOPRIOPORTDST="6662 6663" This would result in the following additional settings to the
tcrules file:3 192.168.1.128/25 0.0.0.0/0 all
3 192.168.3.28 0.0.0.0/0 all
3 0.0.0.0/0 60.0.0.0/24 all
3 0.0.0.0/0 0.0.0.0/0 udp 6662,6663
3 0.0.0.0/0 0.0.0.0/0 udp - 6662,6663
3 0.0.0.0/0 0.0.0.0/0 tcp 6662,6663
3 0.0.0.0/0 0.0.0.0/0 tcp - 6662,6663A simple setupThis is a simple setup for people sharing an internet connection
and using different computers for this. It just basically shapes
between 2 hosts which have the ip addresses 192.168.2.23 and
192.168.2.42tcdevices file#INTERFACE IN-BANDWITH OUT-BANDWIDTH
ppp0 6000kbit 700kbitWe have 6mbit down and 700kbit upstream.tcclasses file#INTERFACE MARK RATE CEIL PRIORITY OPTIONS
ppp0 1 10kbit 50kbit 1 tcp-ack
ppp0 2 300kbit full 2
ppp0 3 300kbit full 2
ppp0 4 90kbit 200kbit 3 defaultWe add a class for tcp ack packets with highest priority, so
that downloads are fast. The following 2 classes share most of the
bandwidth between the 2 hosts, if the connection is idle, they may
use full speed. As the hosts should be treated equally they have the
same priority. The last class is for the remaining traffic.tcrules file#MARK SOURCE DEST PROTO PORT(S) CLIENT USER
# PORT(S)
1:F 0.0.0.0/0 0.0.0.0/0 icmp echo-request
1:F 0.0.0.0/0 0.0.0.0/0 icmp echo-reply
2:F 192.168.2.23 0.0.0.0/0 all
3:F 192.168.2.42 0.0.0.0/0 allWe mark icmp ping and replies so they will go into the fast
interactive class and set a mark for each host.A Warning to Xen UsersIf you are running traffic shaping in your dom0 and traffic shaping
doesn't seem to be limiting outgoing traffic properly, it may be due to
"checksum offloading" in your domU(s). Check the output of "shorewall show
tc". Here's an excerpt from the output of that command:class htb 1:130 parent 1:1 leaf 130: prio 3 quantum 1500 rate 76000bit ceil 230000bit burst 1537b/8 mpu 0b overhead 0b cburst 1614b/8 mpu 0b overhead 0b level 0
Sent 559018700 bytes 75324 pkt (dropped 0, overlimits 0 requeues 0)
rate 299288bit 3pps backlog 0b 0p requeues 0
lended: 53963 borrowed: 21361 giants: 90174
tokens: -26688 ctokens: -14783There are two obvious problems in the above output:The rate (299288) is considerably larger than the ceiling
(230000).There are a large number (90174) of giants reported.This problem will be corrected by disabling "checksum offloading" in
your domU(s) using the ethtool utility. See the one of the Xen articles for
instructions.Intermediate Frame Block (IFB) DevicesBeginning with Shorewall 4.1.6, Shorewall-perl includes support for
IFBs. The principles behind an IFB is fairly simple:It looks like a network interface although it is never given an
IPv4 configuration.Because it is a network interface, queuing disciplines can be
associated with an IFB.The magic of an IFB comes in the fact that a filter may be defined
on a real network interface such that each packet that arrives on that
interface is queued for the IFB! In that way, the IFB provides a means for
shaping input traffic.To use an IFB, you must have IFB support in your kernel
(configuration option CONFIG_IFB). Assuming that you have a modular
kernel, the name of the IFB module is 'ifb' and may be loaded using the
command modprobe ifb (if you have modprobe installed)
or insmod /path/to/module/ifb.By default, two IFB devices (ifb0 and ifb1) are created. You can
control that using the numifbs option (e.g., modprobe ifb
numifbs=1).To create a single IFB when Shorewall starts, place the following
two commands in /etc/shorewall/init:modprobe ifb numifbs=1
ip link set ifb0 upEntries in /etc/shorewall/tcrules have no
effect on shaping traffic through an IFB. To allow classification of such
traffic, the /etc/shorewall/tcfilters file has been added. Entries in that
file create u32
classification rules./etc/shorewall/tcfiltersWhile this file was created to allow shaping of traffic through an
IFB, the file may be used for general traffic classification as well.
The file is similar to shorewall-tcrules(5) with the
following key exceptions:The first match determines the classification, whereas in the
tcrules file, the last match determines the classification.ipsets are not supportedDNS Names are not supportedfilters are applied to packets as they appear on the
wire. So incoming packets will not have DNAT applied yet
(the destination IP address will be the external address) and
outgoing packets will have had SNAT applied.The last point warrants elaboration. When looking at traffic being
shaped by an IFB, there are two cases to consider:Requests — packets being sent from remote clients to local
servers. These packets may undergo subsequent DNAT, either as a
result of entries in /etc/shorewall/nat or as a
result of DNAT or REDIRECT rules.Example: /etc/shorewall/rules:#ACTION SOURCE DEST PROTO DEST SOURCE ORIGINAL
# PORT(S) PORT(S) DEST
DNAT net dmz:192.168.4.5 tcp 80 - 206.124.146.177Requests redirected by this rule will have destination IP
address 206.124.146.177 and destination port 80.Responses — packets being sent from remote servers to local
clients. These packets may undergo subsequent DNAT as a result of
entries in /etc/shorewall/nat or in
/etc/shorewall/masq. The packet's destination
IP address will be the external address specified in the
entry.Example:
/etc/shorewall/masq:#INTERFACE SOURCE ADDRESS
eth0 192.168.1.0/24 206.124.146.179HTTP response packets corresponding to requests that fall
under that rule will have destination IP address 206.124.146.179 and
source port 80.Columns in the file are as follow. As in all Shorewall
configuration files, a hyphen ("-") may be used to indicate that no
value is supplied in the column.CLASSThe interface name or number followed by a colon (":") and
the class number.SOURCESOURCE IP address (host or network). DNS names are not
allowed.DESTDESTINATION IP address (host or network). DNS names are not
allowed.PROTOProtocol name or number.DEST PORT(S)Comma-separated list of destination port names or numbers.
May only be specified if the protocol is TCP, UDP, SCTP or ICMP.
Port ranges are supported except for ICMP.SOURCE PORTComma-separated list of source port names or numbers. May
only be specified if the protocol is TCP, UDP or SCTP. Port ranges
are supported.Example:I've used this configuration on my own firewall. The IFB portion
is more for test purposes rather than to serve any well-reasoned QOS
strategy./etc/shorewall/init:qt modprobe ifb numifbs=1
qt ip link set dev ifb0 up/etc/shorewall/tcdevices:#INTERFACE IN-BANDWITH OUT-BANDWIDTH OPTIONS REDIRECTED
# INTERFACES
1:eth0 - 384kbit classify
2:ifb0 - 1300kbit - eth0/etc/shorewall/tcclasses:#INTERFACE MARK RATE CEIL PRIORITY OPTIONS
1:110 - 5*full/10 full 1 tcp-ack,tos-minimize-delay
1:120 - 2*full/10 6*full/10 2 default
1:130 - 2*full/10 6*full/10 3
2:110 - 5*full/10 full 1 tcp-ack,tos-minimize-delay
2:120 - 2*full/10 6*full/10 2 default
2:130 - 2*full/10 6*full/10 3/etc/shorewall/tcfilters:#INTERFACE: SOURCE DEST PROTO DEST SOURCE
#CLASS PORT(S) PORT(S)
#
# OUTGOING TRAFFIC
#
1:130 206.124.146.178 - tcp - 49441,49442 #BITTORRENT on wookie
1:110 206.124.146.178 #wookie
1:110 206.124.146.179 #SNAT of internal systems
1:110 206.124.146.180 #Work Laptop
1:110 - - icmp echo-request,echo-reply
1:110 - - icmp echo-reply
1:130 206.124.146.177 - tcp - 873,25 #Bulk Traffic
#
# INCOMING TRAFFIC
#
2:110 - 206.124.146.178 #Wookie
2:110 - 206.124.146.179 #SNAT Responses
2:110 - 206.124.146.180 #Work Laptop
2:130 - 206.124.146.177 tcp 25 #Incoming Email.You can examine the installed filters with the shorewall
show filters command. What follows shows the output for
eth0 with the filters shown
above. Bold font are comments
explaining the rules.gateway:~ # shorewall-lite show filters
Shorewall Lite 4.1.6 Clasifiers at gateway - Fri Mar 21 08:06:47 PDT 2008
Device eth1:
Device eth2:
Device eth0:
filter parent 1: protocol ip pref 10 u32
filter parent 1: protocol ip pref 10 u32 fh 3: ht divisor 1 <========= Start of table 3. parses TCP header
filter parent 1: protocol ip pref 10 u32 fh 3::800 order 2048 key ht 3 bkt 0 flowid 1:130 (rule hit 102 success 0)
match 03690000/ffff0000 at nexthdr+0 (success 0 ) <========= SOURCE PORT 873 goes to class 1:130
filter parent 1: protocol ip pref 10 u32 fh 2: ht divisor 1 <========= Start of table 2. parses ICMP header
filter parent 1: protocol ip pref 10 u32 fh 2::800 order 2048 key ht 2 bkt 0 flowid 1:110 (rule hit 0 success 0)
match 08000000/ff000000 at nexthdr+0 (success 0 ) <========= ICMP Type 8 goes to class 1:110
filter parent 1: protocol ip pref 10 u32 fh 2::801 order 2049 key ht 2 bkt 0 flowid 1:110 (rule hit 0 success 0)
match 00000000/ff000000 at nexthdr+0 (success 0 ) <========= ICMP Type 0 goes to class 1:110
filter parent 1: protocol ip pref 10 u32 fh 1: ht divisor 1 <========= Start of table 1. parses TCP header
filter parent 1: protocol ip pref 10 u32 fh 1::800 order 2048 key ht 1 bkt 0 flowid 1:130 (rule hit 0 success 0)
match c1210000/ffff0000 at nexthdr+0 (success 0 ) <========= SOURCE PORT 49441 goes to class 1:130
filter parent 1: protocol ip pref 10 u32 fh 1::801 order 2049 key ht 1 bkt 0 flowid 1:130 (rule hit 0 success 0)
match c1220000/ffff0000 at nexthdr+0 (success 0 ) <========= SOURCE PORT 49442 goes to class 1:130
filter parent 1: protocol ip pref 10 u32 fh 800: ht divisor 1 <========= Start of Table 800. Packets start here!=============== The following 2 rules are generated by the class definition in /etc/shorewall/classes ==================
filter parent 1: protocol ip pref 10 u32 fh 800::800 order 2048 key ht 800 bkt 0 flowid 1:110 (rule hit 2204 success 138)
match 00060000/00ff0000 at 8 (success 396 ) <========= TCP
match 05000000/0f00ffc0 at 0 (success 250 ) <========= Header length 20 and Packet Length < 64
match 00100000/00ff0000 at 32 (success 138 ) <========= ACK
filter parent 1: protocol ip pref 10 u32 fh 800::801 order 2049 key ht 800 bkt 0 flowid 1:110 (rule hit 2066 success 0)
match 00100000/00100000 at 0 (success 0 ) <========= Minimize-delay goes to class 1:110 =============== Jump to Table 1 if the matches are met ==================
filter parent 1: protocol ip pref 10 u32 fh 800::802 order 2050 key ht 800 bkt 0 link 1: (rule hit 2066 success 0)
match ce7c92b2/ffffffff at 12 (success 1039 ) <========= SOURCE 206.124.146.178
match 00060000/00ff0000 at 8 (success 0 ) <========= PROTO TCP
offset 0f00>>6 at 0 eat
filter parent 1: protocol ip pref 10 u32 fh 800::803 order 2051 key ht 800 bkt 0 flowid 1:110 (rule hit 2066 success 1039)
match ce7c92b2/ffffffff at 12 (success 1039 ) <========= SOURCE 206.124.146.178 goes to class 1:110
filter parent 1: protocol ip pref 10 u32 fh 800::804 order 2052 key ht 800 bkt 0 flowid 1:110 (rule hit 1027 success 132)
match ce7c92b3/ffffffff at 12 (success 132 ) <========= SOURCE 206.124.146.179 goes to class 1:110
filter parent 1: protocol ip pref 10 u32 fh 800::805 order 2053 key ht 800 bkt 0 flowid 1:110 (rule hit 895 success 603)
match ce7c92b4/ffffffff at 12 (success 603 ) <========= SOURCE 206.124.146.180 goes to class 1:110 =============== Jump to Table 2 if the matches are met ==================
filter parent 1: protocol ip pref 10 u32 fh 800::806 order 2054 key ht 800 bkt 0 link 2: (rule hit 292 success 0)
match 00010000/00ff0000 at 8 (success 0 ) <========= PROTO ICMP
offset 0f00>>6 at 0 eat
=============== Jump to Table 3 if the matches are met ==================
filter parent 1: protocol ip pref 10 u32 fh 800::807 order 2055 key ht 800 bkt 0 link 3: (rule hit 292 success 0)
match ce7c92b1/ffffffff at 12 (success 265 ) <========= SOURCE 206.124.146.177
match 00060000/00ff0000 at 8 (success 102 ) <========= PROTO TCP
offset 0f00>>6 at 0 eat Understanding the output of 'shorewall show tc'The shorewall show tc (shorewall-lite
show tc) command displays information about the current state of
traffic shaping. For each device, it executes the following
commands: echo Device $device:
tc -s -d qdisc show dev $device
echo
tc -s -d class show dev $device
echo So, the traffic-shaping output is generated entirely by the
tc utility.Here's the output of for eth0. The configuration is the one shown in
the preceding section (the output was obtained almost 24 hours later than
the shorewall show filters output shown above).Device eth0:
============== The primary queuing discipline is HTB (Hierarchical Token Bucket) ====================
qdisc htb 1: r2q 10 default 120 direct_packets_stat 9 ver 3.17
Sent 2133336743 bytes 4484781 pkt (dropped 198, overlimits 4911403 requeues 21) <=========== Note the overlimits and dropped counts
rate 0bit 0pps backlog 0b 8p requeues 21
============== The ingress filter. If you specify IN-BANDWIDTH, you can see the 'dropped' count here. =========In this case, the packets are being sent to the IFB for shaping
qdisc ingress ffff: ----------------
Sent 4069015112 bytes 4997252 pkt (dropped 0, overlimits 0 requeues 0)
rate 0bit 0pps backlog 0b 0p requeues 0
============ Each of the leaf HTB classes has an SFQ qdisc to ensure that each flow gets its turn ============
qdisc sfq 110: parent 1:110 limit 128p quantum 1514b flows 128/1024 perturb 10sec
Sent 613372519 bytes 2870225 pkt (dropped 0, overlimits 0 requeues 6)
rate 0bit 0pps backlog 0b 0p requeues 6
qdisc sfq 120: parent 1:120 limit 128p quantum 1514b flows 128/1024 perturb 10sec
Sent 18434920 bytes 60961 pkt (dropped 0, overlimits 0 requeues 0)
rate 0bit 0pps backlog 0b 0p requeues 0
qdisc sfq 130: parent 1:130 limit 128p quantum 1514b flows 128/1024 perturb 10sec
Sent 1501528722 bytes 1553586 pkt (dropped 198, overlimits 0 requeues 15)
rate 0bit 0pps backlog 11706b 8p requeues 15
============= Class 1:110 -- the high-priority class ===========
Note the rate and ceiling calculated from 'full'
class htb 1:110 parent 1:1 leaf 110: prio 1 quantum 4800 rate 192000bit ceil 384000bit burst 1695b/8 mpu 0b overhead 0b cburst 1791b/8 mpu 0b overhead 0b level 0
Sent 613372519 bytes 2870225 pkt (dropped 0, overlimits 0 requeues 0)
rate 195672bit 28pps backlog 0b 0p requeues 0 <=========== Note the current rate of traffic. There is no queuing (no packet backlog)
lended: 2758458 borrowed: 111773 giants:
tokens: 46263 ctokens: 35157
============== The root class ============
class htb 1:1 root rate 384000bit ceil 384000bit burst 1791b/8 mpu 0b overhead 0b cburst 1791b/8 mpu 0b overhead 0b level 7
Sent 2133276316 bytes 4484785 pkt (dropped 0, overlimits 0 requeues 0) <==== Total output traffic since last 'restart'
rate 363240bit 45pps backlog 0b 0p requeues 0
lended: 1081936 borrowed: 0 giants: 0
tokens: -52226 ctokens: -52226
============= Bulk Class (outgoing rsync, email and bittorrent) ============
class htb 1:130 parent 1:1 leaf 130: prio 3 quantum 1900 rate 76000bit ceil 230000bit burst 1637b/8 mpu 0b overhead 0b cburst 1714b/8 mpu 0b overhead 0b level 0
Sent 1501528722 bytes 1553586 pkt (dropped 198, overlimits 0 requeues 0)
rate 162528bit 14pps backlog 0b 8p requeues 0 <======== Queuing is occurring (8 packet backlog). The rate is still below the ceiling.
lended: 587134 borrowed: 966459 giants: 0 During peak activity, the rate tops out at around 231000 (just above ceiling).
tokens: -30919 ctokens: -97657
================= Default class (mostly serving web pages) ===============
class htb 1:120 parent 1:1 leaf 120: prio 2 quantum 1900 rate 76000bit ceil 230000bit burst 1637b/8 mpu 0b overhead 0b cburst 1714b/8 mpu 0b overhead 0b level 0
Sent 18434920 bytes 60961 pkt (dropped 0, overlimits 0 requeues 0)
rate 2240bit 2pps backlog 0b 0p requeues 0
lended: 57257 borrowed: 3704 giants: 0
tokens: 156045 ctokens: 54178
Using your own tc scriptReplacing builtin tcstart fileIf you prefer your own tcstart file, just install it in
/etc/shorewall/tcstart.In your tcstart script, 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.Set TC_ENABLED=Yes and CLEAR_TC=YesSupply an /etc/shorewall/tcstart script to configure your
traffic shaping rules.Optionally supply an /etc/shorewall/tcclear script to stop
traffic shaping. That is usually unnecessary.If your tcstart script uses the fwmark
classifier, you can mark packets using entries in
/etc/shorewall/tcrules.Traffic control outside ShorewallTo 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:Set TC_ENABLED=No and CLEAR_TC=NoIf your script uses the fwmark classifier, you
can mark packets using entries in /etc/shorewall/tcrules.Testing ToolsAt least one Shorewall user has found this tool helpful: http://e2epi.internet2.edu/network-performance-toolkit.html