SNMP

A lot of Wi-Fi access points and Wi-Fi routers support the Simple Network Management Protocol (SNMP). This is a standardized method for monitoring/managing network connected devices. SNMP uses a tree-like hierarchy where each node is an object. Many of these objects contain (live) lists of instances and metrics, like network interfaces, disks and Wi-Fi registrations.

There is currently support for the following device types within Home Assistant:

• Presence detection
• Sensor
  • Finding OIDs
  • Examples
    • Printer uptime minutes
• Switch

Presence detection

The following OID examples pull the current MAC Address table from a router. This reflects all recent devices seen on the network. However, since devices are not removed until they time out, this is less effective for device tracker integration page than desirable. It is recommended to use Ping or Nmap instead.

To use the SNMP version 1 or 2c platform in your installation, add the following to your configuration.yaml file:

# Example configuration.yaml entry for SNMP version 1 or 2c
device_tracker:
  - platform: snmp
    host: 192.168.1.1
    community: public
    baseoid: 1.3.6.1.4.1.14988.1.1.1.2.1.1

If you want to use encryption, you must enable SNMP version 3 by adding auth_key and priv_key variables and enabling SNMP version 3 on your router. Currently only SHA1 is supported for authentication and AES for encryption. Example of SNMPv3 configuration:

# Example configuration.yaml entry for SNMP version 3
device_tracker:
  - platform: snmp
    host: 192.168.1.1
    community: USERNAME
    auth_key: AUTHPASS
    priv_key: PRIVPASS
    baseoid: 1.3.6.1.4.1.14988.1.1.1.2.1.1

See the device tracker integration page for instructions how to configure the people to be tracked.

Using templates

For incoming data, a value template translates incoming JSON or raw data to a valid payload. Incoming payloads are rendered with possible JSON values, so when rendering, the value_json can be used to access the attributes in a JSON based payload, otherwise the value variable can be used for non-json based data.

Additional, the this can be used as variables in the template. The this attribute refers to the current entity state of the entity. Further information about this variable can be found in the template documentation

{ "state": "ON", "temperature": 21.902 }

Sensor

The snmp sensor platform displays information available through the Simple Network Management Protocol (SNMP). SNMP uses a tree-like hierarchy where each node is an object, and is mainly supported by network-oriented devices such as routers, modems and printers.

To enable this sensor in your installation, add the following to your configuration.yaml file:

# Example configuration.yaml entry
sensor:
  - platform: snmp
    host: 192.168.1.32
    baseoid: 1.3.6.1.4.1.2021.10.1.3.1

Valid values for auth_protocol:

• none
• hmac-md5
• hmac-sha
• hmac128-sha224
• hmac192-sha256
• hmac256-sha384
• hmac384-sha512

Valid values for priv_protocol:

• none
• des
• 3des-ede
• aes-cfb-128
• aes-cfb-192
• aes-cfb-256

Finding OIDs

OIDs may vary on different systems because they are vendor-specific. Besides the device’s manual, the OID Repository is a good place to start if you are looking for OIDs. As an example, the following OIDs are for the load of a Linux system.

• 1 minute Load: 1.3.6.1.4.1.2021.10.1.3.1
• 5 minute Load: 1.3.6.1.4.1.2021.10.1.3.2
• 15 minute Load: 1.3.6.1.4.1.2021.10.1.3.3

There is a large amount of tools available to work with SNMP. snmpwalk let you easily retrieve the value of an OID.

$ snmpwalk -Os -c public -v 2c 192.168.1.32 1.3.6.1.4.1.2021.10.1.3.1
laLoad.1 = STRING: 0.19

Examples

Printer uptime minutes

According to the most common SNMP standard, the uptime of a device is accessible under OID 1.3.6.1.2.1.1.3.0. The value represented using a format called TimeTicks, in units of hundredths of a second.

To create a sensor that displays the uptime for your printer in minutes, you can use this configuration:

# Example configuration.yaml entry
sensor:
  - platform: snmp
    name: "Printer uptime"
    host: 192.168.2.21
    baseoid: 1.3.6.1.2.1.1.3.0
    accept_errors: true
    unit_of_measurement: "minutes"
    value_template: "{{((value | int) / 6000) | int}}"

The accept_errors option will allow the sensor to work even if the printer is not on when Home Assistant is first started: the sensor will just display a - instead of a minute count.

The value_template option converts the original value to minutes.

Switch

The snmp switch platform allows you to control SNMP-enabled equipment.

Currently, only SNMP OIDs that accept integer values are supported. SNMP v1, v2c and v3 are supported.

To use an SNMP switch in your installation:

# Example configuration.yaml entry:
switch:
  - platform: snmp
    host: 192.168.0.2
    baseoid: 1.3.6.1.4.1.19865.1.2.1.4.0

You should check with your device’s vendor to find out the correct BaseOID and what values turn the switch on and off.

Valid values for auth_protocol:

• none
• hmac-md5
• hmac-sha
• hmac128-sha224
• hmac192-sha256
• hmac256-sha384
• hmac384-sha512

Valid values for priv_protocol:

• none
• des
• 3des-ede
• aes-cfb-128
• aes-cfb-192
• aes-cfb-256

Valid values for vartype:

• Counter32
• Counter64
• Gauge32
• Integer32
• Integer
• IpAddress
• ObjectIdentifier
• OctetString
• Opaque
• TimeTicks
• Unsigned32

Complete examples:

switch:
  - platform: snmp
    name: SNMP v1 switch
    host: 192.168.0.2
    community: private
    baseoid: 1.3.6.1.4.1.19865.1.2.1.4.0
    payload_on: 1
    payload_off: 0

  - platform: snmp
    name: SNMP v3 switch
    host: 192.168.0.3
    version: "3"
    username: "myusername"
    auth_key: "myauthkey"
    auth_protocol: "hmac-sha"
    priv_key: "myprivkey"
    priv_protocol: "aes-cfb-128"
    baseoid: 1.3.6.1.4.1.19865.1.2.1.4.0
    payload_on: 1
    payload_off: 0

  - platform: snmp
    name: Enable PoE on Netgear switch port 2 using SNMP v3
    host: 192.168.0.4
    version: "3"
    username: "myusername"
    auth_key: "myauthkey"
    auth_protocol: "hmac-sha"
    priv_key: "myprivkey"
    priv_protocol: "des"
    baseoid: 1.3.6.1.4.1.4526.11.15.1.1.1.1.1.2
    payload_on: 15400
    payload_off: 3000
    vartype: Gauge32