NAME

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

SYNOPSIS

         LoadPlugin snmp
         # ...
         <Plugin snmp>
           <Data "powerplus_voltge_input">
             Type "voltage"
             Table false
             Instance "input_line1"
             Scale 0.1
             Values "SNMPv2-SMI::enterprises.6050.5.4.1.1.2.1"
           </Data>
           <Data "hr_users">
             Type "users"
             Table false
             Instance ""
             Shift -1
             Values "HOST-RESOURCES-MIB::hrSystemNumUsers.0"
           </Data>
           <Data "std_traffic">
             Type "if_octets"
             Table true
             Instance "IF-MIB::ifDescr"
             Values "IF-MIB::ifInOctets" "IF-MIB::ifOutOctets"
           </Data>

           <Host "some.switch.mydomain.org">
             Address "192.168.0.2"
             Version 1
             Community "community_string"
             Collect "std_traffic"
             Interval 120
           </Host>
           <Host "some.server.mydomain.org">
             Address "192.168.0.42"
             Version 2
             Community "another_string"
             Collect "std_traffic" "hr_users"
           </Host>
           <Host "some.ups.mydomain.org">
             Address "192.168.0.3"
             Version 1
             Community "more_communities"
             Collect "powerplus_voltge_input"
             Interval 300
           </Host>
         </Plugin>

DESCRIPTION

       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.

CONFIGURATION

       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 details.

       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 false:

           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.

SEE ALSO

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

AUTHOR

       Florian Forster <octo@verplant.org>