Agentless Monitoring with PRTG

Agentless monitoring is a method of overseeing the performance, availability, and overall health of IT infrastructure, applications, and networks without requiring the installation of dedicated software agents on the monitored devices or systems. This approach contrasts with agent-based monitoring, which necessitates deploying a software agent on each monitored device to collect and report data.

Here are some key aspects of agentless monitoring:

• Remote data collection: Data is gathered using standard protocols such as SNMP (Simple Network Management Protocol), WMI (Windows Management Instrumentation), SSH (Secure Shell), or HTTP/S (Hypertext Transfer Protocol Secure). The network monitoring tool communicates directly with the devices or systems over the network to collect performance metrics, logs, and status information.
• Ease of deployment: Agentless monitoring simplifies the setup process as there is no need to install and maintain for example SNMP agents on each device. It also reduces the overhead associated with software installation, updates, and compatibility issues.
• Reduced system impact: Agentless monitoring minimizes the resource consumption on the monitored devices since there is no additional agent software running locally. It is suitable for environments where installing agents might be impractical or impossible, such as legacy systems or third-party managed devices.
• Scalability: Agentless monitoring is often easier to scale as new devices can be added to the monitoring system without the need for individual agent deployments. Centralized configuration and management make it straightforward to expand monitoring capabilities across large and diverse environments.

Choosing between agent-based and agentless monitoring depends on the specific needs of the IT environment:

• Agent-Based Monitoring is suitable for environments requiring detailed, real-time monitoring and where the overhead of managing agents is acceptable.
• Agentless Monitoring is ideal for environments where ease of deployment and minimal system impact are priorities, and where less granular data is sufficient.

Agentless monitoring offers several benefits and limitations that make it suitable for certain environments and less ideal for others.

Benefits of agentless monitoring:

• Quick setup: Since there's no need to install agents on each device, setup is straightforward and faster.
• No installation required: Simplifies the process, especially in environments with numerous devices or where installing software agents is impractical.
• Resource efficiency: Does not consume local system resources such as CPU and memory on the monitored devices.
• No local footprint: Avoids potential performance degradation or conflicts caused by running additional software on the devices.
• Lower maintenance overhead: Eliminates the need for ongoing agent updates, compatibility checks, and troubleshooting.
• Centralized management: Configuration and updates are handled centrally, reducing the operational burden on IT staff.

Limitations of agentless monitoring:

• Connectivity reliance: Heavily dependent on network availability and quality. If the network is down or experiencing issues, data collection can be interrupted.
• Latency and bandwidth: May experience higher latency in data collection and potential bandwidth usage concerns, especially in large environments.
• Exposure: Remote monitoring might expose the system to potential security risks if the protocols used are not properly secured.
• Access controls: Requires careful configuration of access controls and permissions to ensure that only authorized monitoring tools can collect data.
• Network load: In very large environments, the sheer volume of data collected over the network can become a burden, potentially affecting network performance.

Agent-based monitoring always requires an intermediary, or a so-called “agent” that is preinstalled by the manufacturer or IT administrator on the system whose performance is to be monitored.

This agent is usually a small piece of software that records then sends monitoring data to the IT monitoring tool. On the other hand, with agentless monitoring data is sent to the monitoring tool directly via built-in protocols or APIs.

In PRTG, “sensors” are the basic monitoring elements. One sensor usually monitors one measured value in your network, for example the traffic of a switch port, the CPU load of a server, or the free space on a disk drive. On average, you need about 5-10 sensors per device or one sensor per switch port.