1Simple action in tc(8)               Linux              Simple action in tc(8)
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NAME

6       simple - basic example action
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SYNOPSIS

9       tc ... action simple [ sdata STRING ] [ index INDEX ] [ CONTROL ]
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11       CONTROL := { reclassify | pipe | drop | continue | ok }
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DESCRIPTION

15       This  is  a  pedagogical example rather than an actually useful action.
16       Upon every access, it prints the given STRING which may be of arbitrary
17       length.
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OPTIONS

20       sdata STRING
21              The actual string to print.
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23       index INDEX
24              Optional action index value.
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26       CONTROL
27              Indicate how tc should proceed after executing the action. For a
28              description of the possible CONTROL values, see tc-actions(8).
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EXAMPLES

31       The following example makes the kernel yell "Incoming ICMP!" every time
32       it sees an incoming ICMP on eth0. Steps are:
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34       1)  Add an ingress qdisc point to eth0
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36       2)  Start  a  chain  on  ingress  of  eth0 that first matches ICMP then
37           invokes the simple action to shout.
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39       3)  display stats and show that no packet has been seen by the action
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41       4)  Send one ping packet to google (expect to receive a response back)
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43       5)  grep the logs to see the logged message
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45       6)  display stats again and observe increment by 1
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47  hadi@noma1:$ tc qdisc add dev eth0 ingress
48  hadi@noma1:$tc filter add dev eth0 parent ffff: protocol ip prio 5 \
49      u32 match ip protocol 1 0xff flowid 1:1 action simple sdata "Incoming ICMP"
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51  hadi@noma1:$ sudo tc -s filter ls  dev eth0 parent ffff:
52   filter protocol ip pref 5 u32
53   filter protocol ip pref 5 u32 fh 800: ht divisor 1
54   filter protocol ip pref 5 u32 fh 800::800 order 2048 key ht 800 bkt 0 flowid 1:1
55     match 00010000/00ff0000 at 8
56     action order 1: Simple <Incoming ICMP>
57      index 4 ref 1 bind 1 installed 29 sec used 29 sec
58      Action statistics:
59          Sent 0 bytes 0 pkt (dropped 0, overlimits 0 requeues 0)
60          backlog 0b 0p requeues 0
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63  hadi@noma1$ ping -c 1 www.google.ca
64  PING www.google.ca (74.125.225.120) 56(84) bytes of data.
65  64 bytes from ord08s08-in-f24.1e100.net (74.125.225.120): icmp_req=1 ttl=53 time=31.3 ms
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67  --- www.google.ca ping statistics ---
68  1 packets transmitted, 1 received, 0% packet loss, time 0ms
69  rtt min/avg/max/mdev = 31.316/31.316/31.316/0.000 ms
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71  hadi@noma1$ dmesg | grep simple
72  [135354.473951] simple: Incoming ICMP_1
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74  hadi@noma1$ sudo tc/tc -s filter ls  dev eth0 parent ffff:
75  filter protocol ip pref 5 u32
76  filter protocol ip pref 5 u32 fh 800: ht divisor 1
77  filter protocol ip pref 5 u32 fh 800::800 order 2048 key ht 800 bkt 0 flowid 1:1
78    match 00010000/00ff0000 at 8
79     action order 1: Simple <Incoming ICMP>
80      index 4 ref 1 bind 1 installed 206 sec used 67 sec
81     Action statistics:
82     Sent 84 bytes 1 pkt (dropped 0, overlimits 0 requeues 0)
83     backlog 0b 0p requeues 0
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SEE ALSO

86       tc(8) tc-actions(8)
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90iproute2                          12 Jan 2015           Simple action in tc(8)
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