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       smokeping_master_slave - How run multiple distributed instances of


       Normally smokeping probes run their tests from the host where smokeping
       runs to some target host and monitor the latency of the connection
       between the two.

       The Master/Slave concept enables all smokeping probes to run remotely.
       The use case for this is to measure the overall connectivity in a
       network. If you are interested in checking that your central DNS server
       or your file server works for everyone, you could setup several
       smokeping instances checking up on on the two servers from multiple
       locations within your network. With the Master/Slave smokeping
       configuration this process becomes much simpler, as one smokeping
       master server can control multiple slaves.

       All monitoring data is stored and presented on the server, but
       collected by the slaves. The slaves will also get their configuration
       information from the master, so that you just have to maintain the
       master server configuration file and the rest is taken care of


       The slaves communicate with the master smokeping server via the normal
       smokeping web interface. On initial startup each slave connects to the
       master server and asks for its assignments. When the slave has done a
       round of probing it connects to the master again to deliver the

       If the assignment for a slave changes, the master will tell the slave
       after the slave has delivered its results.

       The master and the slaves sign their messages by supplying an HMAC-MD5
       code (RFC 2104) of the message and a shared secret. Optionally the
       whole communication can run over ssl.

           [slave 1]     [slave 2]      [slave 3]
               |             |              |
               +-------+     |     +--------+
                       |     |     |
                       v     v     v
                     |    master     |

       The slave is a normal smokeping instance setup where the configuration
       comes from the master instead of a local configuration file. The slave
       tries to contact the master server after every round of probing,
       supplying its results. If the master server can not be reached, the
       results will be sent to the server together with the next round of
       results. Results will be stored in a perl storable so that they survive
       a restart of the smokeping instance.

   Master Configuration
       To configure a master/slave setup, add a slaves section to your
       smokeping configuration file. Each slave has a section in the slaves
       part of the master configuration file. The section name must match the
       hostname of the slave. If some configuration parameter must be set to a
       special value for the slave, use an override section to configure this.

       The slave names must be the names the hosts think they have not their
       outside hostnames or ip addresses or anything like that. When the slave
       calls the master to get its config or report its measurements it will
       tell the master its ’hostname’. This together with the shared secret is
       used to authenticate and identify who is who.

        *** Slaves ***


        Probes.FPing.binary = /usr/bin/fping

       Then in the targets section you can define slaves at every level. Again
       the settings get inherited by lower order targets and can be
       overwritten anywhere in the tree.

       A slave will then get the appropriate configuration assigned by the

        *** Targets ***
        slaves = slave1 slave2
        slaves =
        slaves = slave1

       The data from the slaves will be stored in TargetName~SlaveName.rrd. So
       the example above would create the following files:


   Slave Configuration
       A smokeping slave setup has no configuration file. It just needs to
       know that it runs in slave-mode and its secret. The secret is stored in
       a file for optimal protection. By default the persistent data cache
       will be located in /tmp/smokeping.$USER.cache.

        ./smokeping --master-url=http://smokeping/smokeping.cgi \
                    --cache-dir=/var/smokeping/ \


       The master effectively has full access to slave hosts as the user the
       slave smokeping instance is run as. The configuration is transferred as
       Perl code that is evaluated on the slave. While this is done inside a
       restricted "Safe" compartment, there are various ways that a malicious
       master could use to embed arbitrary commands in the configuration and
       get them to run when the slave probes its targets.

       The strength of the shared secret is thus of paramount importance.
       Brute forcing the secret would enable a man-in-the-middle to inject a
       malicious new configuration and compromise the slave.


       Copyright (c) 2007 by Tobias Oetiker, OETIKER+PARTNER AG. All right


       This program is free software; you can redistribute it and/or modify it
       under the terms of the GNU General Public License as published by the
       Free Software Foundation; either version 2 of the License, or (at your
       option) any later version.

       This program is distributed in the hope that it will be useful, but
       WITHOUT ANY WARRANTY; without even the implied warranty of
       General Public License for more details.

       You should have received a copy of the GNU General Public License along
       with this program; if not, write to the Free Software Foundation, Inc.,
       675 Mass Ave, Cambridge, MA 02139, USA.


       Tobias Oetiker <>