:plugin: snmp
:type: input
:no_codec:

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START - GENERATED VARIABLES, DO NOT EDIT!
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:version: %VERSION%
:release_date: %RELEASE_DATE%
:changelog_url: %CHANGELOG_URL%
:include_path: ../../../../logstash/docs/include
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END - GENERATED VARIABLES, DO NOT EDIT!
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[id="plugins-{type}s-{plugin}"]

=== SNMP input plugin

include::{include_path}/plugin_header.asciidoc[]

==== Description

The SNMP input polls network devices using Simple Network Management Protocol (SNMP)
to gather information related to the current state of the devices operation.

The SNMP input plugin supports SNMP v1, v2c, and v3 over UDP and TCP transport protocols.

[id="plugins-{type}s-{plugin}-ecs"]
==== Compatibility with the Elastic Common Schema (ECS)

Because SNMP data has specific field names based on OIDs, we recommend setting a <<plugins-{type}s-{plugin}-target>>.
Metadata fields follow a specific naming convention when <<plugins-{type}s-{plugin}-ecs_compatibility,ECS compatibility mode>> is enabled.

[cols="<l,<l,e,<e"]
|=======================================================================
|ECS disabled |ECS v1, v8 |Description
|[@metadata][host_protocol]    |[@metadata][input][snmp][host][protocol]    |The protocol used to retrieve data e.g. "udp"
|[@metadata][host_address]     |[@metadata][input][snmp][host][address]     |The host IP e.g. "192.168.1.1"
|[@metadata][host_port]        |[@metadata][input][snmp][host][port]        |The host's port e.g. "161"
|[@metadata][host_community]   |[@metadata][input][snmp][host][community]   |The configured community e.g. "public"
|[host]                        |[host][ip]                                  |Same as `[@metadata][host_address]`, host's IP address
|=======================================================================

[id="plugins-{type}s-{plugin}-import-mibs"]
==== Importing MIBs 

This plugin already includes the IETF MIBs (management information bases) and these do not need to be imported.

Any other MIB will need to be manually imported to provide mapping of the numeric OIDs to MIB field names in the resulting event.

To import a MIB, the OSS https://www.ibr.cs.tu-bs.de/projects/libsmi/[libsmi library] is required.
libsmi is available and installable on most operating systems.

To import a MIB, you need to first convert the ASN.1 MIB file into a `.dic` file using the libsmi `smidump` command line utility.

*Example (using `RFC1213-MIB` file)*

[source,sh]
-----
$ smidump --level=1 -k -f python RFC1213-MIB > RFC1213-MIB.dic
-----

Note that the resulting file as output by `smidump` must have the `.dic` extension.

[id="plugins-{type}s-{plugin}-locate-mibs"]
===== Preventing a `failed to locate MIB module` error 

The `smidump` function looks for mib dependencies in its pre-configured path lists.
You may need to provide the paths to locations of MIBs in your particular environment.

You can avoid  to avoid a `failed to locate MIB module` error by providing the additional path configuration information with:

* an environment variable, or 
* a config file to provide the additional path configuration.

See the "MODULE LOCATIONS" section of the https://www.ibr.cs.tu-bs.de/projects/libsmi/smi_config.html[smi_config documentation] for more info. 

[id="plugins-{type}s-{plugin}-env-var"]
===== Option 1: Use an environment variable 

Set the `SMIPATH` env var with the path to your mibs.
Be sure to include a prepended colon (`:`) for the path.

[source,sh]
-----
$ SMIPATH=":/path/to/mibs/" smidump -k -f python CISCO-PROCESS-MIB.mib > CISCO-PROCESS-MIB_my.dic <1>
-----
<1> Notice the colon that preceeds the path definition. 

[id="plugins-{type}s-{plugin}-mib-config"]
===== Option 2: Provide a coniguration file

The other approach is to create a configuration file with the `path` option. For example, you could create a file called `smi.conf`.

[source,sh]
-----
path :/path/to/mibs/
-----

Use the config with smidump:

[source,sh]
-----
$ smidump -c smi.conf -k -f python CISCO-PROCESS-MIB.mib > CISCO-PROCESS-MIB_my.dic
-----

[id="plugins-{type}s-{plugin}-options"]
==== SNMP Input Configuration Options

This plugin supports the following configuration options plus the <<plugins-{type}s-{plugin}-common-options>> described later.

[cols="<,<,<",options="header",]
|=======================================================================
|Setting |Input type|Required
| <<plugins-{type}s-{plugin}-ecs_compatibility>> |<<string,string>>|No
| <<plugins-{type}s-{plugin}-get>> |<<array,array>>|No
| <<plugins-{type}s-{plugin}-hosts>> |<<array,array>>|No
| <<plugins-{type}s-{plugin}-interval>> |<<number,number>>|No
| <<plugins-{type}s-{plugin}-mib_paths>> |<<path,path>>|No
| <<plugins-{type}s-{plugin}-oid_root_skip>> |<<number,number>>|No
| <<plugins-{type}s-{plugin}-oid_path_length>> |<<number,number>>|No
| <<plugins-{type}s-{plugin}-walk>> |<<array,array>>|No
| <<plugins-{type}s-{plugin}-tables>> |<<array,array>>|No
| <<plugins-{type}s-{plugin}-target>> |<<string,string>>|No
|=======================================================================

==== SNMPv3 Authentication Options

This plugin supports the following SNMPv3 authentication options.

[cols="<,<,<",options="header",]
|=======================================================================
|Setting |Input type|Required
| <<plugins-{type}s-{plugin}-auth_pass>> |<<password,password>>|No
| <<plugins-{type}s-{plugin}-auth_protocol>> |<<string,string>>, one of `["md5", "sha", "sha2", "hmac128sha224", "hmac192sha256", "hmac256sha384", "hmac384sha512"]`|No
| <<plugins-{type}s-{plugin}-priv_pass>> |<<password,password>>|No
| <<plugins-{type}s-{plugin}-priv_protocol>> |<<string,string>>, one of `["des", "3des", "aes", "aes128", "aes192", "aes256"]`|No
| <<plugins-{type}s-{plugin}-security_level>> |<<string,string>>, one of `["noAuthNoPriv", "authNoPriv", "authPriv"]`|No
| <<plugins-{type}s-{plugin}-security_name>> |<<string,string>>|No
|=======================================================================

==== SNMP Input Configuration Options

Also see <<plugins-{type}s-{plugin}-common-options>> for a list of options supported by all
input plugins.

[id="plugins-{type}s-{plugin}-get"]
===== `get`

  * Value type is <<array,array>>
  * There is no default value for this setting

Use the `get` option to query for scalar values for the given OID(s).
One or more OID(s) are specified as an array of strings of OID(s).

Example
[source,ruby]
-----
input {
  snmp {
    get => ["1.3.6.1.2.1.1.1.0", "1.3.6.1.2.1.1.3.0", "1.3.6.1.2.1.1.5.0"]
    hosts => [{host => "udp:127.0.0.1/161" community => "public"}]
  }
}
-----

[id="plugins-{type}s-{plugin}-hosts"]
===== `hosts`

  * Value type is <<array,array>>
  * There is no default value for this setting

The `hosts` option specifies the list of hosts to query the configured `get` and `walk` options.

Each host definition is a hash and must define the `host` key and value.
`host` must use the format `{tcp|udp}:{ip address}/{port}`, for example `host => "udp:127.0.0.1/161"`

Each host definition can optionally include the following keys and values:

* `community` the community string, default is `public`.
* `version` `1`, `2c` or `3`, default is `2c`.
* `retries` is the number of retries in case of failure, default is `2`.
* `timeout` is the timeout in milliseconds with a default value of `1000`.

*Specifying all hosts options*

[source,ruby]
-----
input {
  snmp {
    get => ["1.3.6.1.2.1.1.1.0"]
    hosts => [{host => "udp:127.0.0.1/161" community => "public" version => "2c"  retries => 2  timeout => 1000}]
  }
}
-----

*Specifying multiple hosts*

[source,ruby]
-----
input {
  snmp {
    get => ["1.3.6.1.2.1.1.1.0"]
    hosts => [{host => "udp:127.0.0.1/161" community => "public"}, {host => "udp:192.168.0.1/161" community => "private"}]
  }
}
-----

*Specifying IPv6 hosts*

[source,ruby]
-----
input {
  snmp {
    get => ["1.3.6.1.2.1.1.1.0"]
    hosts => [{host => "udp:[::1]/161" community => "public"}, {host => "udp:[2001:db8::2:1]/161" community => "private"}]
  }
}
-----

[id="plugins-{type}s-{plugin}-interval"]
===== `interval`

  * Value type is <<number,number>>
  * Default value is `30`

The `interval` option specifies the polling interval in seconds.
If polling all configured hosts takes longer than this interval, a warning will be emitted to the logs.

[id="plugins-{type}s-{plugin}-mib_paths"]
===== `mib_paths`

  * Value type is <<path,path>>
  * There is no default value for this setting

The `mib_paths` option specifies the location of one or more imported MIB files.
The value can be either a dir path containing the imported MIB `.dic` files or a
file path to a single MIB `.dic` file.

This plugin includes the IETF MIBs.
If you require other MIBs, you need to import them. See <<plugins-{type}s-{plugin}-import-mibs>>.

[id="plugins-{type}s-{plugin}-oid_root_skip"]
===== `oid_root_skip`

  * Value type is <<number,number>>
  * Default value is `0`

The `oid_root_skip` option specifies the number of OID root digits to ignore in the event field name.
For example, in a numeric OID like "1.3.6.1.2.1.1.1.0" the first 5 digits could be ignored by setting `oid_root_skip => 5`
which would result in a field name "1.1.1.0". Similarly when a MIB is used an OID such
"1.3.6.1.2.mib-2.system.sysDescr.0" would become "mib-2.system.sysDescr.0"

[id="plugins-{type}s-{plugin}-oid_path_length"]
===== `oid_path_length`

  * Value type is <<number,number>>
  * Default value is `0`

The `oid_path_length` option specifies the number of OID root digits to retain in the event field name.
For example, in a numeric OID like "1.3.6.1.2.1.1.1.0" the last 2 digits could be retained by setting `oid_path_length => 2`
which would result in a field name "1.0". Similarly when a MIB is used an OID such
"1.3.6.1.2.mib-2.system.sysDescr.0" would become "sysDescr.0"

[id="plugins-{type}s-{plugin}-walk"]
===== `walk`

  * Value type is <<array,array>>
  * There is no default value for this setting

Use the `walk` option to retrieve the subtree of information for the given OID(s).
One or more OID(s) are specified as an array of strings of OID(s).

Queries the subtree of information starting at the given OID(s).

Example
[source,ruby]
-----
  snmp {
    walk => ["1.3.6.1.2.1.1"]
    hosts => [{host => "udp:127.0.0.1/161" community => "public"}]
  }
}
-----

[id="plugins-{type}s-{plugin}-tables"]
===== `tables`

  * Value type is <<array,array>>
  * There is no default value for this setting
  * Results are returned under a field using the table name

The `tables` option is used to query for tabular values for the given column OID(s).

Each table definition is a hash and must define the name key and value and the columns to return.

*Specifying a single table*

[source,ruby]
-----
input {
  snmp {
    hosts => [{host => "udp:127.0.0.1/161" community => "public" version => "2c"  retries => 2  timeout => 1000}]
    tables => [ {"name" => "interfaces" "columns" => ["1.3.6.1.2.1.2.2.1.1", "1.3.6.1.2.1.2.2.1.2", "1.3.6.1.2.1.2.2.1.5"]} ]
  }
}
-----

*Specifying multiple tables*

[source,ruby]
-----
input {
  snmp {
    get => ["1.3.6.1.2.1.1.1.0"]
    tables => [ {"name" => "interfaces" "columns" => ["1.3.6.1.2.1.2.2.1.1", "1.3.6.1.2.1.2.2.1.2", "1.3.6.1.2.1.2.2.1.5"]}, {"name" => "ltmPoolStatTable" "columns" => ["1.3.6.1.4.1.3375.2.2.5.2.3.1.1", "1.3.6.1.4.1.3375.2.2.5.2.3.1.6"]} ]
  }
}
-----

==== SNMPv3 Authentication Options

A **single user** can be configured and will be used for all defined SNMPv3 hosts.
Multiple snmp input declarations will be needed if multiple SNMPv3 users are required.
These options are required only if you are using SNMPv3.

[id="plugins-{type}s-{plugin}-auth_pass"]
===== `auth_pass`

  * Value type is <<password,password>>
  * There is no default value for this setting

The `auth_pass` option specifies the SNMPv3 authentication passphrase or password.

[id="plugins-{type}s-{plugin}-auth_protocol"]
===== `auth_protocol`

The `auth_protocol` option specifies the SNMPv3 authentication protocol or type

* Value can be any of: `md5`, `sha`, `sha2`, `hmac128sha224`, `hmac192sha256`, `hmac256sha384`, `hmac384sha512`
* There is no default value for this setting

[id="plugins-{type}s-{plugin}-ecs_compatibility"]
===== `ecs_compatibility`

  * Value type is <<string,string>>
  * Supported values are:
    ** `disabled`: does not use ECS-compatible field names (fields might be set at the root of the event)
    ** `v1`, `v8`: avoids field names that might conflict with Elastic Common Schema (for example, the `host` field)
  * Default value depends on which version of Logstash is running:
    ** When Logstash provides a `pipeline.ecs_compatibility` setting, its value is used as the default
    ** Otherwise, the default value is `disabled`.

Controls this plugin's compatibility with the {ecs-ref}[Elastic Common Schema (ECS)].

[id="plugins-{type}s-{plugin}-priv_pass"]
===== `priv_pass`

  * Value type is <<password,password>>
  * There is no default value for this setting

The `priv_pass` option specifies the SNMPv3 encryption password.

[id="plugins-{type}s-{plugin}-priv_protocol"]
===== `priv_protocol`

  * Value can be any of: `des`, `3des`, `aes`, `aes128`, `aes192`, `aes256`
  * Note that `aes` and `aes128` are equivalent
  * There is no default value for this setting

The `priv_protocol` option specifies the SNMPv3 privacy/encryption protocol.

[id="plugins-{type}s-{plugin}-security_name"]
===== `security_name`

  * Value type is <<string,string>>
  * There is no default value for this setting

The `security_name` option specifies the SNMPv3 security name or user name.

[id="plugins-{type}s-{plugin}-security_level"]
===== `security_level`

  * Value can be any of: `noAuthNoPriv`, `authNoPriv`, `authPriv`
  * There is no default value for this setting

The `security_level` option specifies the SNMPv3 security level between
Authentication, No Privacy; Authentication, Privacy; or no Authentication, no Privacy. 

[id="plugins-{type}s-{plugin}-target"]
===== `target`

  * Value type is <<string,string>>
  * There is no default value for this setting

The name of the field under which SNMP payloads are assigned.
If not specified data will be stored in the root of the event.

Setting a target is recommended when <<plugins-{type}s-{plugin}-ecs_compatibility>> is enabled.

[id="plugins-{type}s-{plugin}-examples"]
==== Configuration examples

*Specifying SNMPv3 settings*

[source,ruby]
-----
input {
  snmp {
    hosts => [{host => "udp:127.0.0.1/161" version => "3"}]
    get => ["1.3.6.1.2.1.1.1.0"]
    security_name => "mySecurityName"
    auth_protocol => "sha"
    auth_pass => "ShaPassword"
    priv_protocol => "aes"
    priv_pass => "AesPasword"
    security_level => "authPriv"
  }
}

-----

*Using both `get` and `walk` in the same poll cycle for each host(s)*

[source,ruby]
-----
input {
  snmp {
    get => ["1.3.6.1.2.1.1.1.0", "1.3.6.1.2.1.1.3.0", "1.3.6.1.2.1.1.5.0"]
    walk => ["1.3.6.1.2.1.1"]
    hosts => [{host => "udp:127.0.0.1/161" community => "public"}]
  }
}
-----

*Specifying all global options* 

[source,ruby]
-----
input {
  snmp {
    get => ["1.3.6.1.2.1.1.1.0"]
    hosts => [{host => "udp:127.0.0.1/161"}]
    
    mib_paths => ["path/to/converted/mibfile.dic"]
    oid_root_skip => 0
    interval => 30
  }
}
-----

==== Polled host information

All the polled host information is stored in the event `@metadata`:

* `[@metadata][host_protocol]` : `udp` or `tcp`
* `[@metadata][host_address]` : host address for example `127.0.0.1`
* `[@metadata][host_port]` : host port (for example `161`)
* `[@metadata][host_community]` : community string for example `public`


By default, a `host` field is added to the event with the `[@metadata][host_address]` value.

[source,ruby]
-----
config :add_field, :validate => :hash, :default => { "host" => "%{[@metadata][host_address]}" }
-----

You can customize the format and content of the `host` field by specifying an alternate `add_field`. 

Example
[source,ruby]
-----
input {
  snmp {
    get => ["1.3.6.1.2.1.1.1.0"]
    hosts => [{host => "udp:127.0.0.1/161"}]
    
    add_field => {host => "%{[@metadata][host_protocol]}:%{[@metadata][host_address]}/%{[@metadata][host_port]},%{[@metadata][host_community]}"}
  }
}
-----

[id="plugins-{type}s-{plugin}-common-options"]
include::{include_path}/{type}.asciidoc[]

:no_codec!:
