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1=========================2Network classifier cgroup3=========================4 5The Network classifier cgroup provides an interface to6tag network packets with a class identifier (classid).7 8The Traffic Controller (tc) can be used to assign9different priorities to packets from different cgroups.10Also, Netfilter (iptables) can use this tag to perform11actions on such packets.12 13Creating a net_cls cgroups instance creates a net_cls.classid file.14This net_cls.classid value is initialized to 0.15 16You can write hexadecimal values to net_cls.classid; the format for these17values is 0xAAAABBBB; AAAA is the major handle number and BBBB18is the minor handle number.19Reading net_cls.classid yields a decimal result.20 21Example::22 23 mkdir /sys/fs/cgroup/net_cls24 mount -t cgroup -onet_cls net_cls /sys/fs/cgroup/net_cls25 mkdir /sys/fs/cgroup/net_cls/026 echo 0x100001 > /sys/fs/cgroup/net_cls/0/net_cls.classid27 28- setting a 10:1 handle::29 30 cat /sys/fs/cgroup/net_cls/0/net_cls.classid31 104857732 33- configuring tc::34 35 tc qdisc add dev eth0 root handle 10: htb36 tc class add dev eth0 parent 10: classid 10:1 htb rate 40mbit37 38- creating traffic class 10:1::39 40 tc filter add dev eth0 parent 10: protocol ip prio 10 handle 1: cgroup41 42configuring iptables, basic example::43 44 iptables -A OUTPUT -m cgroup ! --cgroup 0x100001 -j DROP45