Sometimes it's necessary to limit traffic bandwidth from and to a [[container]].You can do it using ordinary <code>tc</code> tool. == Packet routes ==First of all, a few words about how packets travel from and to a [[container]].Suppose we have [[Hardware Node]] (HN) with a container (CT) on itI was really confused, and thiscontainer talks to some Remote Host (RH). HN has one "real" network interface<tt>eth0</tt> and, thanks to OpenVZ, there is also "virtual" network interface <tt>venet0</tt>.Inside the container we have interface <tt>venet0:0</tt>. <pre> venet0:0 venet0 eth0CT >------------->-------------> HN >--------->--------> RH venet0:0 venet0 eth0CT <-------------<-------------< HN <---------<--------< RH</pre> == Limiting outgoing bandwidth ==We can limit container outgoing bandwidth by setting the <tt>tc</tt> filter on <tt>eth0</tt>.<pre>DEV=eth0tc qdisc del dev $DEV roottc qdisc add dev $DEV root handle 1: cbq avpkt 1000 bandwidth 100mbittc class add dev $DEV parent 1: classid 1:1 cbq rate 256kbit allot 1500 prio 5 bounded isolatedtc filter add dev $DEV parent 1: protocol ip prio 16 u32 match ip src X.X.X.X flowid 1:1tc qdisc add dev $DEV parent 1:1 sfq perturb 10</pre>X.X.X.X is an IP address of container. == Limiting incoming bandwidth ==This can be done by setting the <code>tc</code> filter on <code>venet0</code>:<pre>DEV=venet0tc qdisc del dev $DEV roottc qdisc add dev $DEV root handle 1: cbq avpkt 1000 bandwidth 100mbittc class add dev $DEV parent 1: classid 1:1 cbq rate 256kbit allot 1500 prio 5 bounded isolatedtc filter add dev $DEV parent 1: protocol ip prio 16 u32 match ip dst X.X.X.X flowid 1:1tc qdisc add dev $DEV parent 1:1 sfq perturb 10</pre>Note that <code>X.X.X.X</code> is an IP address of container. == Limiting CT to HN talks ==As you can see, two filters above don't limit [[container]] to [[HN]] talks.I mean a [[container]] can emit as much traffic as it wishes. To make such a limitation from the [[HN]],it is necessary to use <tt>tc</tt> police on <tt>venet0</tt>:<pre>DEV=venet0tc filter add dev $DEV parent 1: protocol ip prio 20 u32 match u32 1 0x0000 police rate 2kbit buffer 10k drop flowid :1</pre> == Limiting packets per second rate from container ==To prevent dos atacks from the container you can limit packets per second rate using iptables.<source lang="bash">DEV=eth0iptables -I FORWARD 1 -o $DEV -s X.X.X.X -m limit --limit 200/sec -j ACCEPTiptables -I FORWARD 2 -o $DEV -s X.X.X.X -j DROP</source>Here <code>X.X.X.X</code> is an IP address of container. == An alternate approch using HTB == For details refer to the [http://luxik.cdi.cz/~devik/qos/htb/ HTB Home Page] <source lang="bash">#!/bin/sh## Incoming traffic control#CT_IP1=$1CT_IP2=$2DEV=venet0#tc qdisc del dev $DEV root#tc qdisc add dev $DEV root handle 1: htb default 10#tc class add dev $DEV parent 1: classid 1:1 htb rate 100mbit burst 15ktc class add dev $DEV parent 1:1 classid 1:10 htb rate 10mbit ceil 10mbit burst 15ktc class add dev $DEV parent 1:1 classid 1:20 htb rate 20mbit ceil 20mbit burst 15ktc class add dev $DEV parent 1:1 classid 1:30 htb rate 30mbit ceil 30mbit burst 15k#tc qdisc add dev $DEV parent 1:10 handle 10: sfq perturb 10tc qdisc add dev $DEV parent 1:20 handle 20: sfq perturb 10tc qdisc add dev $DEV parent 1:30 handle 30: sfq perturb 10#if [ ! -z $CT_IP1 ]; then tc filter add dev $DEV protocol ip parent 1:0 prio 1 u32 match ip dst "$CT_IP1" flowid 1:20 fiif [ ! -z $CT_IP2 ]; then tc filter add dev $DEV protocol ip parent 1:0 prio 1 u32 match ip dst "$CT_IP2" flowid 1:30 fi#echo;echo "tc configuration for $DEV:"tc qdisc show dev $DEVtc class show dev $DEVtc filter show dev $DEV## Outgoing traffic control#DEV=eth0#tc qdisc del dev $DEV root#tc qdisc add dev $DEV root handle 1: htb default 10#tc class add dev $DEV parent 1: classid 1:1 htb rate 100mbit burst 15ktc class add dev $DEV parent 1:1 classid 1:10 htb rate 10mbit ceil 10mbit burst 15ktc class add dev $DEV parent 1:1 classid 1:20 htb rate 20mbit ceil 20mbit burst 15ktc class add dev $DEV parent 1:1 classid 1:30 htb rate 30mbit ceil 30mbit burst 15k#tc qdisc add dev $DEV parent 1:10 handle 10: sfq perturb 10tc qdisc add dev $DEV parent 1:20 handle 20: sfq perturb 10tc qdisc add dev $DEV parent 1:30 handle 30: sfq perturb 10#if [ ! -z $CT_IP1 ]; then tc filter add dev $DEV protocol ip parent 1:0 prio 1 u32 match ip src "$CT_IP1" flowid 1:20fiif [ ! -z $CT_IP2 ]; then tc filter add dev $DEV protocol ip parent 1:0 prio 1 u32 match ip src "$CT_IP2" flowid 1:30fi#echo;echo "tc configuration for $DEV:"tc qdisc show dev $DEVtc class show dev $DEVtc filter show dev $DEV</source> == External links ==* [http://lartcanswered all my qeustonis.org/howto/ Linux Advanced Routing & Traffic Control HOWTO] [[Category: HOWTO]][[Category: Networking]]
