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       collectd-snmp - Documentation of collectd's "snmp plugin"


         LoadPlugin snmp
         # ...
         <Plugin snmp>
           <Data "powerplus_voltge_input">
             Type "voltage"
             Table false
             Instance "input_line1"
             Scale 0.1
             Values "SNMPv2-SMI::enterprises.6050."
           <Data "hr_users">
             Type "users"
             Table false
             Instance ""
             Shift -1
             Values "HOST-RESOURCES-MIB::hrSystemNumUsers.0"
           <Data "std_traffic">
             Type "if_octets"
             Table true
             Instance "IF-MIB::ifDescr"
             Values "IF-MIB::ifInOctets" "IF-MIB::ifOutOctets"

           <Host "">
             Address ""
             Version 1
             Community "community_string"
             Collect "std_traffic"
             Interval 120
           <Host "">
             Address ""
             Version 2
             Community "another_string"
             Collect "std_traffic" "hr_users"
           <Host "">
             Address ""
             Version 1
             Community "more_communities"
             Collect "powerplus_voltge_input"
             Interval 300


       The "snmp plugin" queries other hosts using SNMP, the simple network
       management protocol, and translates the value it receives to collectd's
       internal format and dispatches them. Depending on the write plugins you
       have loaded they may be written to disk or submitted to another
       instance or whatever you configured.

       Because querying a host via SNMP may produce a timeout multiple threads
       are used to query hosts in parallel. Depending on the number of hosts
       between one and ten threads are used.


       Since the aim of the "snmp plugin" is to provide a generic interface to
       SNMP, it's configuration is not trivial and may take some time.

       Since the "Net-SNMP" library is used you can use all the environment
       variables that are interpreted by that package. See snmpcmd(1) for more

       There are two types of blocks that can be contained in the
       "<Plugin snmp>" block: Data and Host:

   The Data block
       The Data block defines a list of values or a table of values that are
       to be queried. The following options can be set:

       Type type
           collectd's type that is to be used, e. g. "if_octets" for interface
           traffic or "users" for a user count. The types are read from the
           TypesDB (see collectd.conf(5)), so you may want to check for which
           types are defined. See types.db(5) for a description of the format
           of this file.

       Table true|false
           Define if this is a single list of values or a table of values. The
           difference is the following:

           When Table is set to false, the OIDs given to Values (see below)
           are queried using the "GET" SNMP command (see snmpget(1)) and
           transmitted to collectd. One value list is dispatched and,
           eventually, one file will be written.

           When Table is set to true, the OIDs given to Values (see below) are
           queried using the "GETNEXT" SNMP command until the subtree is left.
           After all the lists (think: all columns of the table) have been
           read several values sets will be dispatches and, eventually,
           several files will be written. If you configure a Type (see above)
           which needs more than one data source (for example "if_octets"
           which needs "rx" and "tx") you will need to specify more than one
           (two, in the example case) OIDs with the Values option. This has
           nothing to do with the Table setting.

           For example, if you want to query the number of users on a system,
           you can use "HOST-RESOURCES-MIB::hrSystemNumUsers.0". This is one
           value and belongs to one value list, therefore Table must be set to
           false. Please note that, in this case, you have to include the
           sequence number (zero in this case) in the OID.

           Counter example: If you want to query the interface table provided
           by the "IF-MIB", e. g. the bytes transmitted. There are potentially
           many interfaces, so you will want to set Table to true. Because the
           "if_octets" type needs two values, received and transmitted bytes,
           you need to specify two OIDs in the Values setting, in this case
           likely "IF-MIB::ifHCInOctets" and "IF-MIB::ifHCOutOctets". But,
           this is because of the Type setting, not the Table setting.

           Since the semantic of Instance and Values depends on this setting
           you need to set it before setting them. Doing vice verse will
           result in undefined behavior.

       Instance Instance
           Sets the type-instance of the values that are dispatched. The
           meaning of this setting depends on whether Table is set to true or

           If Table is set to true, Instance is interpreted as an SNMP-prefix
           that will return a list of values. Those values are then used as
           the actual type-instance. An example would be the "IF-MIB::ifDescr"
           subtree.  variables(5) from the SNMP distribution describes the
           format of OIDs.

           If Table is set to true and Instance is omitted, then "SUBID" will
           be used as the instance.

           If Table is set to false the actual string configured for Instance
           is copied into the value-list. In this case Instance may be empty,
           i. e.  "".

       InstancePrefix String
           If Table is set to true, you may feel the need to add something to
           the instance of the files. If set, String is prepended to the
           instance as determined by querying the agent. When Table is set to
           false this option has no effect.

           The "UPS-MIB" is an example where you need this setting: It has
           voltages of the inlets, outlets and the battery of an UPS. However,
           it doesn't provide a descriptive column for these voltages. In this
           case having 1, 2, ... as instances is not enough, because the inlet
           voltages and outlet voltages may both have the subids 1, 2, ... You
           can use this setting to distinguish between the different voltages.

       Values OID [OID ...]
           Configures the values to be queried from the SNMP host. The meaning
           slightly changes with the Table setting. variables(5) from the SNMP
           distribution describes the format of OIDs.

           If Table is set to true, each OID must be the prefix of all the
           values to query, e. g. "IF-MIB::ifInOctets" for all the counters of
           incoming traffic. This subtree is walked (using "GETNEXT") until a
           value from outside the subtree is returned.

           If Table is set to false, each OID must be the OID of exactly one
           value, e. g. "IF-MIB::ifInOctets.3" for the third counter of
           incoming traffic.

       Scale Value
           The gauge-values returned by the SNMP-agent are multiplied by
           Value.  This is useful when values are transfered as a fixed point
           real number. For example, thermometers may transfer 243 but
           actually mean 24.3, so you can specify a scale value of 0.1 to
           correct this. The default value is, of course, 1.0.

           This value is not applied to counter-values.

       Shift Value
           Value is added to gauge-values returned by the SNMP-agent after
           they have been multiplied by any Scale value. If, for example, a
           thermometer returns degrees Kelvin you could specify a shift of
           273.15 here to store values in degrees Celsius. The default value
           is, of course, 0.0.

           This value is not applied to counter-values.

   The Host block
       The Host block defines which hosts to query, which SNMP community and
       version to use and which of the defined Data to query.

       The argument passed to the Host block is used as the hostname in the
       data stored by collectd.

       Address IP-Address|Hostname
           Set the address to connect to.

       Version 1|2
           Set the SNMP version to use. When giving 2 version "2c" is actually
           used.  Version 3 is not supported by this plugin.

       Community Community
           Pass Community to the host.

       Collect Data [Data ...]
           Defines which values to collect. Data refers to one of the Data
           block above. Since the config file is read top-down you need to
           define the data before using it here.

       Interval Seconds
           Collect data from this host every Seconds seconds. This option is
           meant for devices with not much CPU power, e. g. network equipment
           such as switches, embedded devices, rack monitoring systems and so
           on. Since the Step of generated RRD files depends on this setting
           it's wise to select a reasonable value once and never change it.


       collectd(1), collectd.conf(5), snmpget(1), snmpgetnext(1),
       variables(5), unix(7)


       Florian Forster <>