=head1 NAME collectd-snmp - Documentation of collectd's C =head1 SYNOPSIS LoadPlugin snmp # ... Type "voltage" Table false Instance "input_line1" Scale 0.1 Values "SNMPv2-SMI::enterprises.6050.5.4.1.1.2.1" Type "users" Table false Instance "" Shift -1 Values "HOST-RESOURCES-MIB::hrSystemNumUsers.0" Type "if_octets" Table true Instance "IF-MIB::ifDescr" Values "IF-MIB::ifInOctets" "IF-MIB::ifOutOctets" Address "192.168.0.2" Version 1 Community "community_string" Collect "std_traffic" Interval 120 Address "192.168.0.42" Version 2 Community "another_string" Collect "std_traffic" "hr_users" Address "192.168.0.3" Version 1 Community "more_communities" Collect "powerplus_voltge_input" Interval 300 =head1 DESCRIPTION The C 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. =head1 CONFIGURATION Since the aim of the C is to provide a generic interface to SNMP, it's configuration is not trivial and may take some time. Since the C library is used you can use all the environment variables that are interpreted by that package. See L for more details. There are two types of blocks that can be contained in the CPluginEsnmpE> block: B and B: =head2 The B block The B block defines a list of values or a table of values that are to be queried. The following options can be set: =over 4 =item B I collectd's type that is to be used, e.Eg. "if_octets" for interface traffic or "users" for a user count. The types are read from the B (see L), so you may want to check for which types are defined. See L for a description of the format of this file. =item B I Define if this is a single list of values or a table of values. The difference is the following: When B
is set to B, the OIDs given to B (see below) are queried using the C SNMP command (see L) and transmitted to collectd. B value list is dispatched and, eventually, one file will be written. When B
is set to B, the OIDs given to B (see below) are queried using the C SNMP command until the subtree is left. After all the lists (think: all columns of the table) have been read B values sets will be dispatches and, eventually, several files will be written. If you configure a B (see above) which needs more than one data source (for example C which needs C and C) you will need to specify more than one (two, in the example case) OIDs with the B option. This has nothing to do with the B
setting. For example, if you want to query the number of users on a system, you can use C. This is one value and belongs to one value list, therefore B
must be set to B. 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 C, e.Eg. the bytes transmitted. There are potentially many interfaces, so you will want to set B
to B. Because the C type needs two values, received and transmitted bytes, you need to specify two OIDs in the B setting, in this case likely C and C. But, this is because of the B setting, not the B
setting. Since the semantic of B and B depends on this setting you need to set it before setting them. Doing vice verse will result in undefined behavior. =item B I Sets the type-instance of the values that are dispatched. The meaning of this setting depends on whether B
is set to I or I: If B
is set to I, I 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 C subtree. L from the SNMP distribution describes the format of OIDs. If B
is set to I and B is omitted, then "SUBID" will be used as the instance. If B
is set to I the actual string configured for I is copied into the value-list. In this case I may be empty, i.Ee. "". =item B I If B
is set to I, you may feel the need to add something to the instance of the files. If set, I is prepended to the instance as determined by querying the agent. When B
is set to I this option has no effect. The C 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,E... as instances is not enough, because the inlet voltages and outlet voltages may both have the subids 1, 2,E... You can use this setting to distinguish between the different voltages. =item B I [I ...] Configures the values to be queried from the SNMP host. The meaning slightly changes with the B
setting. L from the SNMP distribution describes the format of OIDs. If B
is set to I, each I must be the prefix of all the values to query, e.Eg. C for all the counters of incoming traffic. This subtree is walked (using C) until a value from outside the subtree is returned. If B
is set to I, each I must be the OID of exactly one value, e.Eg. C for the third counter of incoming traffic. =item B I The gauge-values returned by the SNMP-agent are multiplied by I. This is useful when values are transfered as a fixed point real number. For example, thermometers may transfer B<243> but actually mean B<24.3>, so you can specify a scale value of B<0.1> to correct this. The default value is, of course, B<1.0>. This value is not applied to counter-values. =item B I I is added to gauge-values returned by the SNMP-agent after they have been multiplied by any B value. If, for example, a thermometer returns degrees Kelvin you could specify a shift of B<273.15> here to store values in degrees Celsius. The default value is, of course, B<0.0>. This value is not applied to counter-values. =back =head2 The Host block The B block defines which hosts to query, which SNMP community and version to use and which of the defined B to query. The argument passed to the B block is used as the hostname in the data stored by collectd. =over 4 =item B
I|I Set the address to connect to. =item B B<1>|B<2> Set the SNMP version to use. When giving B<2> version C<2c> is actually used. Version 3 is not supported by this plugin. =item B I Pass I to the host. =item B I [I ...] Defines which values to collect. I refers to one of the B block above. Since the config file is read top-down you need to define the data before using it here. =item B I Collect data from this host every I seconds. This option is meant for devices with not much CPU power, e.Eg. network equipment such as switches, embedded devices, rack monitoring systems and so on. Since the B of generated RRD files depends on this setting it's wise to select a reasonable value once and never change it. =back =head1 SEE ALSO L, L, L, L, L, L =head1 AUTHOR Florian Forster Eocto@verplant.orgE =cut