Provided by: munin-node_1.4.6-3ubuntu3_all bug


       Munin::Plugin::SNMP - Net::SNMP subclass for Munin plugins


       The Munin::Plugin::SNMP module extends Net::SNMP with methods useful for Munin plugins.


       SNMP plugins (that use this module) share a common configuration interface implemented in
       the function session().  Please see the documentation for that function for complete
       instructions and examples on how to configure SNMP.  The documentation is located there to
       ensure that it is up to date and matches the code.


       Additional debugging messages can be enabled by setting $Munin::Plugin::SNMP::DEBUG,
       $Munin::Plugin::DEBUG, or by exporting the "MUNIN_DEBUG" environment variable before
       running the plugin (by passing the "--pidebug" option to "munin-run", for instance).


   config_session() - Decode environment to get the needed plugin configuration parameters
         ($host, $port, $version, $tail) = Munin::Plugin::SNMP->config_session();

       This is a convenience function for the "config" part of the plugin - it decodes the
       environment/plugin name to retrieve the information needed in the configuration phase.  It
       returns a 4 tuple consisting of:

       1) the host name
       2) the udp port to use
       3) the SNMP version to use (3 for version 3, 2 for version 1 or 2c)
       4) the tail of the plugin name: whatever is left of the plugin name after "snmp_<host>_".

       The tail can be interesting for the "fetch" part of the plugin as well.

   session([optional Net::SNMP options]) - create new Munin::Plugin::SNMP object
         $session = Munin::Plugin::SNMP->session();

       This method overrides the Net::SNMP constructor to get the connection information from the
       plugin name and/or environment.  Please note that no error string is returned.  The
       function handles errors internaly - giving a error message and calling die.  Calling die
       is the right thing to do.

       The host name is taken from the plugin symlink, which must be on the form

       The "v3" form is taken to mean that SNMPv3 is to be used.  It is also a name trick
       providing a separate "namespace" for devices that use SNMPv3 so it can be configured
       separately in munin/plugin-conf.d/ files.  E.g.:

            env.version 2

            env.v3username snmpoperator
            env.v3authpassword s3cr1tpa55w0rd

       See below for how to configure for each different case.  The first case above shows
       Munin's default configuration.

       NOTE: munin-node-configure does not yet utilize the "v3" thing.

       The following environment variables are consulted:
           If the plugin name (symlink) does not contain the host name this is used as the host
           name to connect to.

           The host name must be specified, but is usually specified in the plugin name.  If the
           hostname somehow does not resolve in DNS (or the hosts file) it is possible to do

                env.version 2c



           The port to connect to.  Default 161.

           The timeout in seconds to use. Default 5.

           The SNMP version to use for the connection. One of 1, 2, 3, snmpv1, snmpv2c or snmpv3.
           SNMP v2 is better as it supports bulk operations.  Therefore 2 is the default in
           Munin::Plugin::SNMP.  If your device supports v3 that may be even better as it
           supports proper security - but the encryption may slow things down.

           Security is handled differently for versions 1/2c and 3.  See below.
           The community name for version 1 and 2c agents. The default is 'public'.  If this
           works your device is probably very insecure and needs a security checkup.

       SNMP 3 authentication
           SNMP v3 has three security levels: "noAuthNoPriv".  If a username and password is
           given it goes up to "authNoPriv".

           If privpassword is given the security level becomes "authPriv" - the connection is
           authenticated and encrypted.

           Note: Encryption can slow down slow or heavily loaded network devices.  For most uses
           authNoPriv will be secure enough --- in SNMP v3 the password is sent over the network
           encrypted in any case.

           Munin::Plugin::SNMP does not support ContextEngineIDs and such for
           authentication/privacy.  If you see the need and know how it should be done please
           send patches!

           For further reading on SNMP v3 security models please consult RFC3414 and the
           documentation for Net::SNMP.

           If version is set to 3 or snmpv3 these variables are used to define authentication:

               SNMPv3 username.  There is no default. Empty username ('') is allowed.

               SNMPv3 authentication password.  Optional when encryption is also enabled, in
               which case defaults to the privacy password.  Authentication requires a
               v3authprotocol, but this defaults to "md5" and may therefore be left unspecified.

               The password is sent encrypted (one way hash) over the network.

               SNMPv3 authentication protocol.  One of 'md5' or 'sha' (HMAC-MD5-96, RFC1321 and
               SHA-1/HMAC-SHA-96, NIST FIPS PIB 180, RFC2264).  The default is 'md5'.

               SNMPv3 privacy password to enable encryption.  An empty ('') password is
               considered as no password and will not enable encryption.

               Privacy requires a v3privprotocol as well as a v3authprotocol and a
               v3authpassword, but all of these are defaulted (to 'des', 'md5', and the
               v3privpassword value, respectively) and may therefore be left unspecified.

               If the v3privpassword is set this setting controls what kind of encryption is used
               to achive privacy in the session.  Only the very weak 'des' encryption method is
               supported officially.  The default is 'des'.

               The implementing perl module (Net::SNMP) also supports '3des' (CBC-3DES-EDE aka
               Triple-DES, NIST FIPS 46-3) as specified in IETF draft-reeder-snmpv3-usm-3desede.
               Whether or not this works with any particular device, we do not know.

   get_hash() - retrieve a table as a hash of hashes
         $result = $session->get_hash(
                                [-callback        => sub {},]     # non-blocking
                                [-delay           => $seconds,]   # non-blocking
                                [-contextengineid => $engine_id,] # v3
                                [-contextname     => $name,]      # v3
                                -baseoid          => $oid,
                                -cols             => \%columns

       This method transforms the -baseoid and -cols to a array of -columns and calls
       "get_entries()" with all the other arguments.  It then transforms the data into a hash of
       hashes in the following manner:

       The keys of the main hash are the last element(s) of the OIDs, after $oid and the matching
       keys from %columns are removed. The values are hashes with keys corresponding to the
       values of %columns hash and values from the subtables corresonding to the keys of

       For this to work, all the keys of "-cols" must have the same number of elements.  Also,
       don't try to specify a next-to-next-to-leaf-node baseoid, the principle it breaks both
       "get_entries" and the logic in "get_hash".

       If (all) the OIDs are unavailable a defined but empty hashref is returned.


                      -baseoid => '', # IF-MIB
                      -cols    => {
                                   1 => 'index',
                                   2 => 'descr',
                                   4 => 'mtu',

       given the following SNMP table:

         IF-MIB::ifIndex.1 = INTEGER: 1
         IF-MIB::ifIndex.2 = INTEGER: 2
         IF-MIB::ifDescr.1 = STRING: lo0
         IF-MIB::ifDescr.2 = STRING: lna0
         IF-MIB::ifType.1 = INTEGER: softwareLoopback(24)
         IF-MIB::ifType.2 = INTEGER: ethernetCsmacd(6)
         IF-MIB::ifMtu.1 = INTEGER: 32768
         IF-MIB::ifMtu.2 = INTEGER: 1500

       will return a hash like this:

         '1' => {
                 'index' => '1',
                 'mtu' => '32768',
                 'descr' => 'lo0'
         '2' => {
                 'index' => '2',
                 'descr' => 'lna0',
                 'mtu' => '1500'

   get_single() - Retrieve a single value by OID
         $uptime = $session->get_single("") || 'U';

       If the call fails to get a value the above call sets $uptime to 'U' which Munin interprets
       as "Undefined" and handles accordingly.

       If you stop to think about it you should probably use "get_hash()" (it gets too much, but
       is good for arrays) or "get_entries()" - it gets exactly what you want, so you mus

   get_by_regex() - Retrive table of values filtered by regex applied to the value
       This example shows the usage for a netstat plugin.

         my $tcpConnState = "";
         my $connections = $session->get_by_regex($tcpConnState, "[1-9]");

       It gets all OIDs based at $tcpConnState and only returns the ones that contain a number in
       the value.




       Ilmari wrote: "get_hash()" doesn't handle tables with sparse indices.

       Nicolai Langfeldt: Actually I think it does.




       Dagfinn Ilmari Mannsaaker, Nicolai Langfeldt Rune Nordboe Skillingstad added timeout


       Copyright (c) 2004-2009 Dagfinn Ilmari Mannsaaker and Nicolai Langfeldt.

       All rights reserved. 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; version 2 dated June, 1991.