:plugin: snmp
:type: input
:no_codec:

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:version: %VERSION%
:release_date: %RELEASE_DATE%
:changelog_url: %CHANGELOG_URL%
:include_path: ../../../../logstash/docs/include
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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}-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}-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}-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
|=======================================================================

==== 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` 

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).

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

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`

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"`

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

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` 

The `interval` option specifies the polling interval in seconds.

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

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

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.

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

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` 

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"

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

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

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"

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

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

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).

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

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`

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.

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

*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`

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

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

[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}-priv_pass"]
===== `priv_pass`

The `priv_pass` option specifies the SNMPv3 encryption password

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

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

The `priv_protocol` option specifies the SNMPv3 privacy/encryption 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

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

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

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

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

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

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

*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"
  }
}

-----

==== More configuration examples

*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!:
