PRTG P18 – Monitor Ubuntu Server Using PRTG (CPU, RAM, Disk, Load)

Proper monitoring is essential for maintaining a stable Linux infrastructure. In this tutorial, you will learn how to Monitor Ubuntu Server using PRTG with SNMP, covering CPU usage, memory consumption, disk space, and system load.

This setup is lightweight, production-ready, and suitable for environments running services like UniFi Controller, web servers, databases, or internal applications.

We will configure:

• SNMP on Ubuntu

• Core health sensors in PRTG

• Threshold recommendations

• Disk monitoring best practices

Let’s begin.

🛠 Step 0 – Enabling SNMP on Ubuntu

Before you can Monitor Ubuntu Server in PRTG, SNMP must be installed and configured.

Install SNMP Service

Run:

Edit SNMP Configuration

Open the configuration file:

Remove all internal configurations and configure concisely for LAN monitoring:

Explanation:

• agentAddress udp:161 → SNMP listens on UDP port 161

• rocommunity public 127.0.0.1 → Local SNMP access

• rocommunity public 192.168.16.0/24 → Allow LAN monitoring

Make sure your PRTG server IP belongs to this subnet.

Restart and Enable SNMP Service

After saving the configuration, restart SNMP:

Your Ubuntu Server is now ready for SNMP-based monitoring.

🖥 Add Ubuntu Device in PRTG

Inside PRTG:

• Add a new device

• Enter Ubuntu Server IP

• Configure SNMP credentials:

  • Version: SNMP v2c

  • Community: public

Once added successfully, proceed to sensor configuration.

📡 Core Sensors to Monitor Ubuntu Server

To properly Monitor Ubuntu Server, you need essential health sensors. Avoid over-monitoring. Focus only on critical system metrics.

🟢 1. Ping v2

Purpose:

→ Check if the server is online

This sensor verifies basic availability.

If Ping fails:

• Server may be down

• Network connectivity issue

• Firewall blocking ICMP

No complex threshold required.

🟢 2. SNMP CPU Load

Add the SNMP CPU Load sensor.

This monitors overall CPU utilization.

Recommended Threshold

Set threshold based on workload:

• Warning: > 70–80%

• Error: > 90%

Why monitor CPU?

High CPU may indicate:

• Heavy service load

• Infinite loops or runaway processes

• DDoS attempts (if public-facing)

• Database overload

Sustained high CPU (not short spikes) should trigger investigation.

🟢 3. SNMP Memory v2

Add SNMP Memory v2 sensor.

This tracks:

• Available memory

• Used memory

• Cached memory

Linux uses aggressive caching. It is normal to see memory usage above 60–70%.

Recommended Threshold

Configure based on real behavior:

• Warning: Available memory < 15%

• Error: Available memory < 5%

Important:

Linux memory ≠ Windows memory behavior.
High usage does not automatically mean a problem.

Investigate only if:

• Memory remains critically low

• Swap usage increases heavily

• Services become unstable

Monitoring memory is critical when running:

• UniFi Controller

• Database services

• Web servers

• Docker containers

🟢 4. SNMP Disk Free v2

Add SNMP Disk Free v2 sensor.

This is extremely important.

Especially monitor:

• / (root partition)

• Partition containing UniFi data

• Any mounted data partition

If disk becomes full:

• Services may crash

• Logs cannot be written

• System may become unstable

Recommended Disk Threshold

For production environments:

• Warning: Free space < 20%

• Error: Free space < 10%

For small partitions (e.g., 20–40GB):

Consider absolute thresholds:

• Warning: < 5 GB

• Error: < 2 GB

Always monitor the partition storing application data.

🎯 Best Practices to Monitor Ubuntu Server

When you Monitor Ubuntu Server with PRTG:

✅ Keep configuration simple
✅ Use SNMP v2c for internal networks
✅ Set realistic thresholds
✅ Avoid adding unnecessary sensors

Do NOT enable every SNMP option blindly.

Focus only on:

• Availability

• CPU

• Memory

• Disk

This keeps PRTG lightweight and scalable.

🚀 Final Thoughts

Monitoring is not about collecting every metric. It is about collecting the right metrics.

With this configuration, you now have a clean and production-ready setup to Monitor Ubuntu Server using PRTG covering:

• CPU load

• RAM usage

• Disk space

• Server availability

This structure ensures stability, early detection of resource exhaustion, and proactive infrastructure management.

Your Ubuntu monitoring is now simple, effective, and enterprise-ready.