collectd-snmp - Documentation of collectd's
Values "IF-MIB::ifInOctets" "IF-MIB::ifOutOctets"
Collect "std_traffic" "hr_users"
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.
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
<Pluginsnmp> block: Data and Host:
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
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
if_octets which needs
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
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::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
- 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
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.
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
- Scale Value
The gauge-values returned by the SNMP-agent are multiplied by Value. This
is useful when values are transferred 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,
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.
- Ignore Value [, Value ...]
The ignore values allows to ignore Instances based on their name and the patterns
specified by the various values you've entered. The match is a glob-type shell
- InvertMatch true|false(default)
The invertmatch value should be use in combination of the Ignore option.
It changes the behaviour of the Ignore option, from a blacklist behaviour
when InvertMatch is set to false, to a whitelist when specified to true.
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|3
Set the SNMP version to use. When giving 2 version
2c is actually used.
- Community Community
Pass Community to the host. (Ignored for SNMPv3).
- Username Username
Sets the Username to use for SNMPv3 security.
- SecurityLevel authPriv|authNoPriv|noAuthNoPriv
Selects the security level for SNMPv3 security.
- Context Context
Sets the Context for SNMPv3 security.
- AuthProtocol MD5|SHA
Selects the authentication protocol for SNMPv3 security.
- AuthPassphrase Passphrase
Sets the authentication passphrase for SNMPv3 security.
- PrivacyProtocol AES|DES
Selects the privacy (encryption) protocol for SNMPv3 security.
- PrivacyPassphrase Passphrase
Sets the privacy (encryption) passphrase for SNMPv3 security.
- 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.
Florian Forster <firstname.lastname@example.org>
Michael Pilat <email@example.com>