Monitor a device with SNMP

NetLock RMM can monitor an SNMP-capable device — a switch, firewall, NAS, UPS, printer, or access point — without installing an agent on it. Instead, an installed NetLock RMM agent on the same network polls the SNMP target on your behalf.

The chain has four parts: an SNMP device (the target definition — address and credentials), an SNMP sensor (what to poll and, optionally, when to alert), a policy the sensor is attached to, and an automation that routes that policy to the agent doing the polling.

Note: The SNMP target itself never runs NetLock RMM software. The polling is done by an ordinary managed device — a Windows, Linux, or macOS machine with the agent installed — that can reach the target on UDP port 161.

Before you start

• A managed device with the NetLock RMM agent installed, on a network from which it can reach the SNMP target on UDP port 161.
• The SNMP target's IP address and access details: the community string for SNMP v1 / v2c, or the username and auth / privacy credentials for SNMP v3.
• Console permissions for Sensors (collections_sensors_enabled, plus collections_sensors_add) — the same permission also governs SNMP device management.

Step 1 — Register the SNMP device

The SNMP device is the target definition. Open Devices (/devices), switch the view to SNMP, and choose Add.

In the Add SNMP Device dialog, fill in:

• Tenant and Location — the tenant and location the device belongs to.
• Name — a label for the device.
• IP Address — the target's address.
• Port — the SNMP port, 161 by default.
• SNMP Version — v1, v2c, or v3.
• For v1 / v2c: Community String (often public for read access).
• For v3: Username, an Auth Protocol (MD5 or SHA) with its password, and optionally a Privacy Protocol (DES or AES) with its password.
• Device Type — router, switch, firewall, printer, UPS, server, access point, or other.
• Notes — optional free text.

Save. The device now appears in the SNMP view, where you can edit or delete it later.

Step 2 — Create an SNMP sensor

The sensor decides what to poll on the target. Open Collections → Sensors, choose Add, and set Category to SNMP. Then pick the SNMP Type — this is the most important choice:

For every type, select the SNMP Device you registered in Step 1 — the sensor takes the target's address and credentials from it.

For SNMP GET and SNMP Walk:

• OID — the object identifier to query. The MIB Browser (the tree icon) helps you locate one.
• OID name — an optional friendly label.
• Condition and Threshold value — when the sensor should trigger (equals, greater than, less than, contains, regex match, and so on).
• Max Walk Results — for Walk only, a cap on how many returned values are evaluated.
• Notification and action thresholds, and an optional action script — these behave the same as for any other sensor (see Chapter 8.3).

For SNMP Monitor:

• Add the OIDs to collect — each with a method (get or walk), the OID, and a display name. The preset buttons (System Info, Interfaces, Storage) add common OID sets in one click.
• There are no thresholds or actions; Monitor sensors only gather data.

Set the sensor's Platform to match the agent that will do the polling, then save.

Note: A sensor copies the SNMP device's address and credentials when it is created. If you later change those details on the SNMP device, re-open and save each sensor that targets it so the change is picked up.

Step 3 — Attach the sensor to a policy

A sensor only runs when a policy carries it. Open the policy assigned to your polling agent, go to the Sensors tab, and enable the SNMP sensor. See Chapter 6 for the policy editor.

Step 4 — Route the policy to the polling agent

A policy only reaches a device through an automation. Make sure an automation routes the policy from Step 3 to the managed device that will poll the SNMP target. See Chapter 5 for the automation model.

Once the policy is assigned, the agent polls the SNMP target on the sensor's schedule.

Verify it worked

• For a GET or Walk sensor: when the condition is met, an event is raised and any configured notification or action runs — check Events (see Chapter 12).
• For a Monitor sensor: the collected readings appear on the SNMP device's detail panel in the SNMP view of the Devices page, and the device's status and last-seen time update automatically.

Ad-hoc checks with SNMP Tools

Separate from sensors, SNMP Tools runs a one-off SNMP query through an agent — useful for testing an OID or confirming reachability before building a sensor. Open a managed device's detail view, choose SNMP Tools, and run a GET or Walk against any target IP.

SNMP Tools requires the devices_snmp_tools permission and the SNMP Tools toggle on the policy's Agent tab (which depends on remote service being enabled — see Chapter 6). It supports SNMP v1 and v2c only.

Troubleshooting

• No data and no events. Confirm the polling agent can reach the target on UDP port 161 — a firewall between them is the most common cause. The SNMP Tools check above is the quickest way to test reachability.
• Authentication failures. Re-check the community string (v1 / v2c) or the v3 username and auth / privacy settings. The target must also permit SNMP read access from the agent's IP.
• The sensor never runs. Confirm the sensor is enabled on a policy and that an automation routes that policy to the polling agent — both are required.
• Wrong OID. Use the MIB Browser when building the sensor, or SNMP Tools to walk the target, to confirm the OID returns the value you expect.

Related

• Chapter 8.3 — Sensors — the sensor library, thresholds, and action scripts.
• Chapter 6 — Policies — attaching sensors to a policy.
• Chapter 5 — Automations — routing a policy to a device.
• Chapter 12 — Events & Audit — where sensor alerts appear.