man/man8/tc-simple.8

   1 .TH "Simple action in tc" 8 "12 Jan 2015" "iproute2" "Linux"
   2
   3 .SH NAME
   4 simple - basic example action
   5 .SH SYNOPSIS
   6 .in +8
   7 .ti -8
   8 .BR tc " ... " "action simple"
   9 [
  10 .BI sdata " STRING"
  11 ] [
  12 .BI index " INDEX"
  13 ] [
  14 .I CONTROL
  15 ]
  16
  17 .ti -8
  18 .IR CONTROL " := {"
  19 .BR reclassify " | " pipe " | " drop " | " continue " | " ok " }"
  20
  21 .SH DESCRIPTION
  22 This is a pedagogical example rather than an actually useful action. Upon every access, it prints the given
  23 .I STRING
  24 which may be of arbitrary length.
  25 .SH OPTIONS
  26 .TP
  27 .BI sdata " STRING"
  28 The actual string to print.
  29 .TP
  30 .BI index " INDEX"
  31 Optional action index value.
  32 .TP
  33 .I CONTROL
  34 Indicate how
  35 .B tc
  36 should proceed after executing the action. For a description of the possible
  37 .I CONTROL
  38 values, see
  39 .BR tc-actions (8).
  40 .SH EXAMPLES
  41 The following example makes the kernel yell "Incoming ICMP!" every time it sees
  42 an incoming ICMP on eth0. Steps are:
  43 .IP 1) 4
  44 Add an ingress qdisc point to eth0
  45 .IP 2) 4
  46 Start a chain on ingress of eth0 that first matches ICMP then invokes the
  47 simple action to shout.
  48 .IP 3) 4
  49 display stats and show that no packet has been seen by the action
  50 .IP 4) 4
  51 Send one ping packet to google (expect to receive a response back)
  52 .IP 5) 4
  53 grep the logs to see the logged message
  54 .IP 6) 4
  55 display stats again and observe increment by 1
  56
  57 .EX
  58   hadi@noma1:$ tc qdisc add dev eth0 ingress
  59   hadi@noma1:$tc filter add dev eth0 parent ffff: protocol ip prio 5 \\
  60          u32 match ip protocol 1 0xff flowid 1:1 action simple sdata "Incoming ICMP"
  61
  62   hadi@noma1:$ sudo tc -s filter ls  dev eth0 parent ffff:
  63    filter protocol ip pref 5 u32
  64    filter protocol ip pref 5 u32 fh 800: ht divisor 1
  65    filter protocol ip pref 5 u32 fh 800::800 order 2048 key ht 800 bkt 0 flowid 1:1
  66      match 00010000/00ff0000 at 8
  67         action order 1: Simple <Incoming ICMP>
  68          index 4 ref 1 bind 1 installed 29 sec used 29 sec
  69          Action statistics:
  70                 Sent 0 bytes 0 pkt (dropped 0, overlimits 0 requeues 0)
  71                 backlog 0b 0p requeues 0
  72
  73
  74   hadi@noma1$ ping -c 1 www.google.ca
  75   PING www.google.ca (74.125.225.120) 56(84) bytes of data.
  76   64 bytes from ord08s08-in-f24.1e100.net (74.125.225.120): icmp_req=1 ttl=53 time=31.3 ms
  77
  78   --- www.google.ca ping statistics ---
  79   1 packets transmitted, 1 received, 0% packet loss, time 0ms
  80   rtt min/avg/max/mdev = 31.316/31.316/31.316/0.000 ms
  81
  82   hadi@noma1$ dmesg | grep simple
  83   [135354.473951] simple: Incoming ICMP_1
  84
  85   hadi@noma1$ sudo tc/tc -s filter ls  dev eth0 parent ffff:
  86   filter protocol ip pref 5 u32
  87   filter protocol ip pref 5 u32 fh 800: ht divisor 1
  88   filter protocol ip pref 5 u32 fh 800::800 order 2048 key ht 800 bkt 0 flowid 1:1
  89     match 00010000/00ff0000 at 8
  90         action order 1: Simple <Incoming ICMP>
  91          index 4 ref 1 bind 1 installed 206 sec used 67 sec
  92         Action statistics:
  93         Sent 84 bytes 1 pkt (dropped 0, overlimits 0 requeues 0)
  94         backlog 0b 0p requeues 0
  95 .EE
  96 .SH SEE ALSO
  97 .BR tc (8)
  98 .BR tc-actions (8)