---
type: Sensor Reference
title: "SNMP Active Sessions OID: hrSystemNumUsers Reference"
description: "The SNMP OID for active login sessions — hrSystemNumUsers (1.3.6.1.2.1.25.1.5.0), what it counts, its limits, and a snmpget example."
resource: "https://snmp-monitoring.info/sensors/ssh-sessions/"
tags: [sensors]
timestamp: 2026-07-11T00:00:00Z
---

# SNMP Active Sessions OID: hrSystemNumUsers Reference

The SNMP OID for active login sessions — hrSystemNumUsers (1.3.6.1.2.1.25.1.5.0), what it counts, its limits, and a snmpget example.

## Related concepts

- Up: [SNMP Sensors & OID Catalog: Every Metric You Can Monitor](/sensors/index.md)

## Frequently asked questions

### What OID shows active users in SNMP?

hrSystemNumUsers at 1.3.6.1.2.1.25.1.5.0 from HOST-RESOURCES-MIB. It's a Gauge32 holding the current number of active user sessions on the host, including SSH logins. It's a scalar, so read it with a GET on the .0 instance.

### Can SNMP show which usernames are logged in?

No. hrSystemNumUsers is only a count — it carries no usernames, source IPs, TTYs, or per-session detail. For identity you have to go to the host's auth logs or a SIEM. SNMP tells you how many sessions exist and that the number changed, not who is behind them.

### What type is hrSystemNumUsers?

It's a Gauge32 — a current-value snapshot that rises and falls as users log in and out, not a cumulative counter. That means you read it directly rather than diffing two polls, and you alert on its absolute value against a baseline.

### How do I baseline session counts?

Poll the OID over a few normal days to learn the typical range, then alert on meaningful deviation from it. On servers that should have no interactive logins, the simplest and strongest rule is to alert whenever the value exceeds zero, then pivot to the auth logs to see who connected.

## Source

Concept generated from https://snmp-monitoring.info/sensors/ssh-sessions/ — the SNMP Monitoring vendor-neutral knowledge base. Content is limited to what that page states (no external claims added here).