1========================= 2Network classifier cgroup 3========================= 4 5The Network classifier cgroup provides an interface to 6tag network packets with a class identifier (classid). 7 8The Traffic Controller (tc) can be used to assign 9different priorities to packets from different cgroups. 10Also, Netfilter (iptables) can use this tag to perform 11actions 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 these 17values is 0xAAAABBBB; AAAA is the major handle number and BBBB 18is the minor handle number. 19Reading net_cls.classid yields a decimal result. 20 21Example:: 22 23 mkdir /sys/fs/cgroup/net_cls 24 mount -t cgroup -onet_cls net_cls /sys/fs/cgroup/net_cls 25 mkdir /sys/fs/cgroup/net_cls/0 26 echo 0x100001 > /sys/fs/cgroup/net_cls/0/net_cls.classid 27 28- setting a 10:1 handle:: 29 30 cat /sys/fs/cgroup/net_cls/0/net_cls.classid 31 1048577 32 33- configuring tc:: 34 35 tc qdisc add dev eth0 root handle 10: htb 36 tc class add dev eth0 parent 10: classid 10:1 htb rate 40mbit 37 38- creating traffic class 10:1:: 39 40 tc filter add dev eth0 parent 10: protocol ip prio 10 handle 1: cgroup 41 42configuring iptables, basic example:: 43 44 iptables -A OUTPUT -m cgroup ! --cgroup 0x100001 -j DROP 45