mirror of https://github.com/agessaman/MeshCore.git synced 2026-10-20 10:12:13 +00:00

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agessaman f339beb22e docs: refresh observer docs and document ota commands

Add ota check/update/branch, display, and diagnostic commands to the
observer guide; condense MQTT_IMPLEMENTATION.md and ALERTS.md; fix the
nonexistent 'set bridge off' instruction; mark the T-LoRa observer envs
parked; update the SNMP build-target list; move local-testing notes to
MQTT_INTERNALS.md; drop MEMORY_MONITORING.md (its script never existed).

2026-10-18 15:00:47 -07:00

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SNMP Agent for MeshCore Observer Firmware

Observer nodes can run a read-only SNMP v2c agent so tools such as Zabbix, LibreNMS, or PRTG can poll radio, MQTT, memory, and network stats.

Protocol: SNMPv2c (read-only, no SET support)
Port: UDP 161 (standard SNMP)
Library: 0neblock/SNMP_Agent
Off by default

Quick Start

# Enable SNMP
set snmp on
reboot

# Verify from a host on the same network
snmpwalk -v2c -c public <device-ip> 1.3.6.1.4.1.99999

CLI Commands

Command	Description
`get snmp`	Show SNMP agent status (`on` / `off`)
`set snmp on`	Enable SNMP agent (restart required)
`set snmp off`	Disable SNMP agent (restart required)
`get snmp.community`	Show SNMP community string
`set snmp.community <string>`	Set community string (restart required, default: `public`)

OID Reference

All OIDs are under the private enterprise subtree 1.3.6.1.4.1.99999 (.iso.org.dod.internet.private.enterprises.99999).

System (.1.x.0)

OID	Type	Description
`.1.1.0`	INTEGER	System uptime (seconds)
`.1.2.0`	STRING	Firmware version
`.1.3.0`	STRING	Node name

Radio (.2.x.0)

OID	Type	Description
`.2.1.0`	INTEGER	Total packets received
`.2.2.0`	INTEGER	Total packets sent
`.2.3.0`	INTEGER	Receive errors (CRC failures, etc.)
`.2.4.0`	INTEGER	Noise floor (dBm)
`.2.5.0`	INTEGER	Last RSSI (dBm)
`.2.6.0`	INTEGER	Last SNR (dB x 4)
`.2.7.0`	INTEGER	Flood packets sent
`.2.8.0`	INTEGER	Direct packets sent
`.2.9.0`	INTEGER	Flood packets received
`.2.10.0`	INTEGER	Direct packets received
`.2.11.0`	INTEGER	Total air time (seconds)

MQTT (.3.x.0)

OID	Type	Description
`.3.1.0`	INTEGER	Connected MQTT slot count
`.3.2.0`	INTEGER	Packet queue depth
`.3.3.0`	INTEGER	Skipped publishes (memory pressure)

Memory (.4.x.0)

OID	Type	Description
`.4.1.0`	INTEGER	Free heap (bytes)
`.4.2.0`	INTEGER	Max allocatable block (bytes)
`.4.3.0`	INTEGER	Free internal RAM (bytes)
`.4.4.0`	INTEGER	Free PSRAM (bytes, 0 if no PSRAM)

Network (.5.x.0)

OID	Type	Description
`.5.1.0`	INTEGER	WiFi RSSI (dBm)

Example Output

$ snmpwalk -v2c -c public 192.168.50.95 1.3.6.1.4.1.99999

SNMPv2-SMI::enterprises.99999.1.1.0 = INTEGER: 18        # uptime 18s
SNMPv2-SMI::enterprises.99999.1.2.0 = STRING: "v1.14.1"  # firmware
SNMPv2-SMI::enterprises.99999.1.3.0 = STRING: "Heltec Repeater"
SNMPv2-SMI::enterprises.99999.2.1.0 = INTEGER: 3         # 3 packets received
SNMPv2-SMI::enterprises.99999.2.4.0 = INTEGER: -96       # noise floor -96 dBm
SNMPv2-SMI::enterprises.99999.2.5.0 = INTEGER: -25       # last RSSI -25 dBm
SNMPv2-SMI::enterprises.99999.4.1.0 = INTEGER: 199612    # ~195 KB free heap
SNMPv2-SMI::enterprises.99999.4.2.0 = INTEGER: 188404    # ~184 KB max alloc
SNMPv2-SMI::enterprises.99999.5.1.0 = INTEGER: -22       # WiFi RSSI -22 dBm

Architecture

The SNMP agent runs inside the existing MQTT FreeRTOS task on Core 0 (the WiFi/network core). No additional task is created.

Radio stats are pushed from Core 1 (mesh task) every 2 seconds via updateRadioStats()
MQTT stats are updated from Core 0 each MQTT task loop iteration
Memory and WiFi stats are read directly in the SNMP loop on Core 0

The agent starts once the network connects with SNMP enabled, and uses about 2-3 KB of RAM.

Build Configuration

WITH_SNMP=1 is set on most ESP32 observer environments. Check a board with grep -n WITH_SNMP variants/<board>/platformio.ini. To add it to another observer env:

build_flags =
  ...
  -D WITH_SNMP=1

build_src_filter =
  ...
  +<helpers/SNMPAgent.cpp>

lib_deps =
  ...
  0neblock/SNMP_Agent

Files

File	Description
`src/helpers/SNMPAgent.h`	SNMP agent wrapper class declaration
`src/helpers/SNMPAgent.cpp`	OID registration and stats update implementation
`src/helpers/CommonCLI.h`	`MQTTPrefs` (`snmp_enabled`, `snmp_community`)
`src/helpers/CommonCLI_Observer.cpp`	CLI commands
`src/helpers/bridges/MQTTBridge.cpp`	SNMP loop integration in `mqttTaskLoop()`
`examples/simple_repeater/MyMesh.cpp`	Radio stats push and agent initialization

Private Enterprise Number

The OIDs use 99999, a placeholder. A real Private Enterprise Number is free from IANA.

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