# SNMP Trap Input Plugin

This service plugin listens for [SNMP][snmp] notifications like traps and inform
requests. Notifications are received on plain UDP with a configurable port.

> [!NOTE]
> The path setting is shared between all instances of all SNMP plugin types!

⭐ Telegraf v1.13.0
🏷️ hardware, network
💻 all

[snmp]: https://datatracker.ietf.org/doc/html/rfc1157

## Service Input <!-- @/docs/includes/service_input.md -->

This plugin is a service input. Normal plugins gather metrics determined by the
interval setting. Service plugins start a service to listen and wait for
metrics or events to occur. Service plugins have two key differences from
normal plugins:

1. The global or plugin specific `interval` setting may not apply
2. The CLI options of `--test`, `--test-wait`, and `--once` may not produce
   output for this plugin

## Global configuration options <!-- @/docs/includes/plugin_config.md -->

Plugins support additional global and plugin configuration settings for tasks
such as modifying metrics, tags, and fields, creating aliases, and configuring
plugin ordering. See [CONFIGURATION.md][CONFIGURATION.md] for more details.

[CONFIGURATION.md]: ../../../docs/CONFIGURATION.md#plugins

## Secret store support

This plugin supports secrets from secret stores for the `sec_name`,
`auth_password` and `priv_password` option.
See the [secret store documentation][SECRETSTORE] for more details on how
to use them.

[SECRETSTORE]: ../../../docs/CONFIGURATION.md#secret-store-secrets

## Configuration

```toml @sample.conf
# Receive SNMP traps
[[inputs.snmp_trap]]
  ## Transport, local address, and port to listen on.  Transport must
  ## be "udp://".  Omit local address to listen on all interfaces.
  ##   example: "udp://127.0.0.1:1234"
  ##
  ## Special permissions may be required to listen on a port less than
  ## 1024.  See README.md for details
  ##
  # service_address = "udp://:162"
  ##
  ## Path to mib files
  ## Used by the gosmi translator.
  ## To add paths when translating with netsnmp, use the MIBDIRS environment variable
  # path = ["/usr/share/snmp/mibs"]
  ##
  ## Timeout running snmptranslate command
  ## Used by the netsnmp translator only
  # timeout = "5s"
  ## Snmp version; one of "1", "2c" or "3".
  # version = "2c"
  ## SNMPv3 authentication and encryption options.
  ##
  ## Security Name.
  # sec_name = "myuser"
  ## Authentication protocol; one of "MD5", "SHA", "SHA224", "SHA256", "SHA384", "SHA512" or "".
  # auth_protocol = "MD5"
  ## Authentication password.
  # auth_password = "pass"
  ## Security Level; one of "noAuthNoPriv", "authNoPriv", or "authPriv".
  # sec_level = "authNoPriv"
  ## Privacy protocol used for encrypted messages; one of "DES", "AES", "AES192", "AES192C", "AES256", "AES256C" or "".
  # priv_protocol = ""
  ## Privacy password used for encrypted messages.
  # priv_password = ""
```

### SNMP backend: `gosmi` vs `netsnmp`

This plugin supports two backends to translate SNMP objects. By default,
Telegraf will use `netsnmp`, however, this option is deprecated and it is
encouraged to migrate to `gosmi`. If users find issues with `gosmi` that do not
occur with `netsnmp` please open a project issue on GitHub.

The SNMP backend setting is a global-level setting that applies to all use of
SNMP in Telegraf. Users can set this option in the `[agent]` configuration via
the `snmp_translator` option. See the [agent configuration][agent] for more
details.

[agent]: /docs/CONFIGURATION.md#agent

### Using a Privileged Port

On many operating systems, listening on a privileged port (a port
number less than 1024) requires extra permission.  Since the default
SNMP trap port 162 is in this category, using telegraf to receive SNMP
traps may need extra permission.

Instructions for listening on a privileged port vary by operating
system. It is not recommended to run telegraf as superuser in order to
use a privileged port. Instead follow the principle of least privilege
and use a more specific operating system mechanism to allow telegraf to
use the port.  You may also be able to have telegraf use an
unprivileged port and then configure a firewall port forward rule from
the privileged port.

To use a privileged port on Linux, you can use setcap to enable the
CAP_NET_BIND_SERVICE capability on the telegraf binary:

```shell
setcap cap_net_bind_service=+ep /usr/bin/telegraf
```

On Mac OS, listening on privileged ports is unrestricted on versions
10.14 and later.

## Metrics

- snmp_trap
  - tags:
    - source (string, IP address of trap source)
    - name (string, value from SNMPv2-MIB::snmpTrapOID.0 PDU)
    - mib (string, MIB from SNMPv2-MIB::snmpTrapOID.0 PDU)
    - oid (string, OID string from SNMPv2-MIB::snmpTrapOID.0 PDU)
    - version (string, "1" or "2c" or "3")
    - context_name (string, value from v3 trap)
    - engine_id (string, value from v3 trap)
    - community (string, value from 1 or 2c trap)
  - fields:
    - Fields are mapped from variables in the trap. Field names are
      the trap variable names after MIB lookup. Field values are trap
      variable values.

## Example Output

```text
snmp_trap,mib=SNMPv2-MIB,name=coldStart,oid=.1.3.6.1.6.3.1.1.5.1,source=192.168.122.102,version=2c,community=public snmpTrapEnterprise.0="linux",sysUpTimeInstance=1i 1574109187723429814
snmp_trap,mib=NET-SNMP-AGENT-MIB,name=nsNotifyShutdown,oid=.1.3.6.1.4.1.8072.4.0.2,source=192.168.122.102,version=2c,community=public sysUpTimeInstance=5803i,snmpTrapEnterprise.0="netSnmpNotificationPrefix" 1574109186555115459
```
