NAME | SYNOPSIS | DESCRIPTION | OPTIONS | EXAMPLES | SEE ALSO | COLOPHON

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

NAME         top

       simple - basic example action

SYNOPSIS         top

       tc ... action simple STRING

DESCRIPTION         top

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

OPTIONS         top

       STRING The actual string to print.

EXAMPLES         top

       The following example makes the kernel yell "Incoming ICMP!" every
       time it sees an incoming ICMP on eth0. Steps are:

       1)  Add an ingress qdisc point to eth0

       2)  Start a chain on ingress of eth0 that first matches ICMP then
           invokes the simple action to shout.

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

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

       5)  grep the logs to see the logged message

       6)  display stats again and observe increment by 1

         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 "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

SEE ALSO         top

       tc(8)

COLOPHON         top

       This page is part of the iproute2 (utilities for controlling TCP/IP
       networking and traffic) project.  Information about the project can
       be found at 
       ⟨http://www.linuxfoundation.org/collaborate/workgroups/networking/iproute2⟩.
       If you have a bug report for this manual page, send it to
       netdev@vger.kernel.org, shemminger@osdl.org.  This page was obtained
       from the project's upstream Git repository 
       ⟨git://git.kernel.org/pub/scm/linux/kernel/git/shemminger/iproute2.git⟩
       on 2017-03-13.  If you discover any rendering problems in this HTML
       version of the page, or you believe there is a better or more up-to-
       date source for the page, or you have corrections or improvements to
       the information in this COLOPHON (which is not part of the original
       manual page), send a mail to man-pages@man7.org

iproute2                         12 Jan 2015          Simple action in tc(8)