xref: /linux/Documentation/admin-guide/cgroup-v1/net_cls.rst (revision c532de5a67a70f8533d495f8f2aaa9a0491c3ad0)
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