.TH "Simple action in tc" 8 "12 Jan 2015" "iproute2" "Linux"

.SH NAME

simple - basic example action

.SH SYNOPSIS

.in +8

.ti -8

.BR tc " ... " "action simple"

[

.BI sdata " STRING"

] [

.BI index " INDEX"

] [

.I CONTROL

]

.ti -8

.IR CONTROL " := {"

.BR reclassify " | " pipe " | " drop " | " continue " | " ok " }"

.SH DESCRIPTION

This is a pedagogical example rather than an actually useful action. Upon every access, it prints the given

.I STRING

which may be of arbitrary length.

.SH OPTIONS

.TP

.BI sdata " STRING"

The actual string to print.

.TP

.BI index " INDEX"

Optional action index value.

.TP

.I CONTROL

Indicate how

.B tc

should proceed after executing the action. For a description of the possible

.I CONTROL

values, see

.BR tc-actions (8).

.SH EXAMPLES

The following example makes the kernel yell "Incoming ICMP!" every time it sees

an incoming ICMP on eth0. Steps are:

.IP 1) 4

Add an ingress qdisc point to eth0

.IP 2) 4

Start a chain on ingress of eth0 that first matches ICMP then invokes the

simple action to shout.

.IP 3) 4

display stats and show that no packet has been seen by the action

.IP 4) 4

Send one ping packet to google (expect to receive a response back)

.IP 5) 4

grep the logs to see the logged message

.IP 6) 4

display stats again and observe increment by 1

.EX

  hadi@noma1:$ tc qdisc add dev eth0 ingress

  hadi@noma1:$tc filter add dev eth0 parent ffff: protocol ip prio 5 \\

	 u32 match ip protocol 1 0xff flowid 1:1 action simple sdata "Incoming ICMP"

  hadi@noma1:$ sudo tc -s filter ls  dev eth0 parent ffff:

   filter protocol ip pref 5 u32

   filter protocol ip pref 5 u32 fh 800: ht divisor 1

   filter protocol ip pref 5 u32 fh 800::800 order 2048 key ht 800 bkt 0 flowid 1:1

     match 00010000/00ff0000 at 8

	action order 1: Simple <Incoming ICMP>

	 index 4 ref 1 bind 1 installed 29 sec used 29 sec

	 Action statistics:

		Sent 0 bytes 0 pkt (dropped 0, overlimits 0 requeues 0)

		backlog 0b 0p requeues 0

  hadi@noma1$ ping -c 1 www.google.ca

  PING www.google.ca (74.125.225.120) 56(84) bytes of data.

  64 bytes from ord08s08-in-f24.1e100.net (74.125.225.120): icmp_req=1 ttl=53 time=31.3 ms

  --- www.google.ca ping statistics ---

  1 packets transmitted, 1 received, 0% packet loss, time 0ms

  rtt min/avg/max/mdev = 31.316/31.316/31.316/0.000 ms

  hadi@noma1$ dmesg | grep simple

  [135354.473951] simple: Incoming ICMP_1

  hadi@noma1$ sudo tc/tc -s filter ls  dev eth0 parent ffff:

  filter protocol ip pref 5 u32

  filter protocol ip pref 5 u32 fh 800: ht divisor 1

  filter protocol ip pref 5 u32 fh 800::800 order 2048 key ht 800 bkt 0 flowid 1:1

    match 00010000/00ff0000 at 8

	action order 1: Simple <Incoming ICMP>

	 index 4 ref 1 bind 1 installed 206 sec used 67 sec

	Action statistics:

	Sent 84 bytes 1 pkt (dropped 0, overlimits 0 requeues 0)

	backlog 0b 0p requeues 0

.EE

.SH SEE ALSO

.BR tc (8)

.BR tc-actions (8)