SNMP Trap Input Plugin

The SNMP Trap plugin is a service input plugin that receives SNMP notifications (traps and inform requests).

Notifications are received on plain UDP. The port to listen is configurable.

Prerequisites

This plugin uses the snmptranslate programs from the net-snmp project. These tools will need to be installed into the PATH in order to be located. Other utilities from the net-snmp project may be useful for troubleshooting, but are not directly used by the plugin.

These programs will load available MIBs on the system. Typically the default directory for MIBs is /usr/share/snmp/mibs, but if your MIBs are in a different location you may need to make the paths known to net-snmp. The location of these files can be configured in the snmp.conf or via the MIBDIRS environment variable. See man 1 snmpcmd for more information.

Configuration

[[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"
  ## Timeout running snmptranslate command
  # timeout = "5s"
  ## Snmp version
  # version = "2c"
  ## SNMPv3 authentication and encryption options.
  ##
  ## Security Name.
  # sec_name = "myuser"
  ## Authentication protocol; one of "MD5", "SHA" 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 = ""

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:

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)
- 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

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 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 sysUpTimeInstance=5803i,snmpTrapEnterprise.0="netSnmpNotificationPrefix" 1574109186555115459

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