Complete Agentless Monitoring

Monitor your entire infrastructure through protocols already running in your environment without any agent deployment

How Does Agentless Monitoring Work and Is It Right for My Infrastructure?

Agentless monitoring collects performance data from devices without installing software on them. It works through native protocols already running in your environment: SNMP for network devices, WMI for Windows servers, SSH for Linux systems, and Flow protocols for traffic analysis. Most infrastructure already supports these protocols out of the box, which is what makes the approach practical at scale.

Paessler PRTG builds on this foundation with 250+ preconfigured sensors and auto-discovery that identifies devices and creates appropriate sensors automatically. Remote probes extend coverage to distributed infrastructure without opening per-device firewall rules. In practice, you're looking at live data within minutes rather than planning a multi-week rollout across your environment.

PRTG monitors via: SNMP (v1, v2c, v3), WMI, SSH/CLI, NetFlow/sFlow/jFlow/IPFIX, HTTP/HTTPS APIs, IPMI/Redfish, Modbus, MQTT, OPC UA, POP3/IMAP/SMTP, and more.

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PRTG is compatible with all major vendors, products, and systems

Monitor Everything in Your IT-Infrastructure

Full Coverage for Every Device Type

Routers, switches, firewalls, none of them run monitoring agents. Industrial equipment, PLCs, SCADA systems, IoT sensors, either lacks an operating system entirely or prohibits third-party software installation for warranty and security reasons. Agent-based monitoring tools simply can't reach this layer. PRTG uses native protocols including SNMP, Modbus, and MQTT to monitor these devices without modification or access to an OS, which in practice covers the parts of your infrastructure that tend to go unmonitored longest.

Monitor Cisco, Juniper, HP, and other network devices via SNMP without installing software
Track industrial equipment (PLCs, SCADA systems) using Modbus, OPC UA, and MQTT protocols
Monitor IoT devices and sensors that lack operating systems or agent support
Use IPMI and Redfish for server hardware health monitoring without OS-level access
250+ device-specific sensors covering major vendors out-of-the-box

Monitoring That's Ready in Minutes, Not Weeks

Having to install agents on hundreds of servers isn't just time-consuming. It's a project: deploying software, configuring credentials, testing connectivity, coordinating with application owners, managing updates afterward. Lean IT teams don't have weeks to spend on monitoring setup, especially when something needs watching now. PRTG auto-discovery finds devices and creates sensors from preconfigured templates automatically. Enter credentials once at the group level and monitoring starts across your entire IT infrastructure without per-device configuration.

Auto-discovery identifies devices and creates sensors automatically, no manual configuration per device
250+ preconfigured device templates covering Windows, Linux, VMware, network gear, databases, and applications
Credentials entered at group level are inherited by all devices discovered beneath
Multiple auto-discovery modes adapt to different environment sizes
Schedule auto-discovery to continuously find new devices as your infrastructure grows

Keep Production Systems Running at Full Speed

Production databases, payment processing servers, and real-time OT controllers run with tight performance margins. Even modest CPU or memory overhead from a monitoring agent shows up in environments like these, and running multiple software agents simultaneously impacts performance. PRTG places all processing load on the PRTG server or remote probes, not on the monitored devices. SNMP, Flow, and Ping sensors are lightweight by design. Flow monitoring specifically uses data your routers and switches already generate, so there's no additional overhead on the device side at all.

SNMP and Ping sensors carry very low performance impact, safe for the most sensitive systems
Flow monitoring (NetFlow, sFlow, jFlow) adds no overhead to monitored devices
All data processing, storage, and alerting run on your PRTG server
For Windows systems where performance is critical, SNMP is the lighter alternative to WMI
Remote probes distribute monitoring load rather than concentrating it

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Start monitoring your infrastructure in minutes. No professional services, no complex configuration, no risk.

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PRODUCT OVERVIEW

Centralized Visibility Across All Sites and Segments

Multi-site infrastructure with network segmentation creates a specific problem: local data collection is necessary but opening dozens of firewall ports per monitored device isn't practical. Plus managing agent updates across WAN links and coordinating with distributed teams adds overhead that compounds over time. PRTG remote probes sit at each site, monitor locally using agentless protocols, and send aggregated monitoring data to your central PRTG server over a single TLS-encrypted connection. One connection per site, not one per device.

Remote probes monitor behind firewalls and transmit data to the central server via encrypted connection
Deploy probes at branch offices, manufacturing plants, or data centers for local collection
Classic remote probes run on Windows, multi-platform probes run on Linux
Each site continues monitoring autonomously if the WAN connection temporarily drops
Centralized dashboards, alerts, and reports across all locations from a single PRTG instance

Immediate Visibility When You Need It Most

Troubleshooting an active incident can't wait for change control approvals and agent deployment windows. Neither can capacity responses or evaluating new infrastructure. This agentless monitoring solution removes that dependency entirely. No software installation on production systems means no change requests, no approval delays, no service restarts required. Point PRTG at the device, enter credentials, and data collection starts within minutes. For urgent situations that's the relevant difference between agent-based approaches and agentless monitoring tools.

No change control needed for monitored systems, monitoring uses read-only protocols
Start monitoring immediately for troubleshooting, incident response, or capacity planning
Add new devices or sensors without scheduling maintenance windows
Temporary monitoring works for proof-of-concept or short-term visibility needs
Auto-discovery completes in minutes for urgent situations

How PRTG Monitors Without Agents

PRTG's agentless monitoring uses native protocols and APIs already available in your infrastructure. Here's an overview of how PRTG's monitoring capabilities work without installing software on monitored devices.

SNMP Monitoring

Most network devices speak SNMP. Routers, switches, firewalls, printers, UPS systems, and server hardware all support it, which is why it's the core protocol of almost every network monitoring tool. PRTG supports v1, v2c, and v3 (v3 with encryption) and ships with 250+ preconfigured SNMP sensors covering major vendors including Cisco, Juniper, HP, Dell, and NetApp. The right OIDs get selected automatically. Performance impact is low enough that SNMP runs safely on production nodes and endpoints where anything heavier would be a problem. Bandwidth, uptime, latency, and interface health are all covered from the start, without additional configuration.

WMI and SSH

WMI and SSH cover the two OS families you're most likely running. On Windows servers, PRTG queries performance counters, system status, and application metrics through WMI without touching the OS beyond credential access. SSH lets PRTG collect data from Linux and Unix systems using preconfigured commands for disk space, CPU load, memory, and process status. Neither method requires software installation on the monitored server. The PRTG probe handles query processing and data storage locally. Virtual machines, databases, web services, and apps stay lightweight on both platforms, which matters more in environments where agent sprawl is already a problem.

Flow Analysis

Flow data is already being generated. Your routers and switches produce it continuously, PRTG just receives and analyzes it. That's what makes flow monitoring genuinely overhead-free on the device side. PRTG supports NetFlow v5 and v9, sFlow, jFlow, and IPFIX from Cisco, Juniper, HP, and other vendors, showing bandwidth usage, top talkers, top connections, and application protocols without packet capture. Mostly useful for troubleshooting bottlenecks and chasing down which endpoints are consuming bandwidth. Also for tracking network performance and capacity planning in distributed or cloud environments where full packet inspection isn't an option.

Remote Probe Architecture

The firewall problem with agent-based monitoring is a port problem. Each monitored device needs reachability, which means firewall rules, and those multiply fast across a distributed environment. PRTG remote probes sidestep this. Each probe sits on a local network segment, monitors devices there using SNMP, WMI, SSH, and other protocols, and sends aggregated data to the central PRTG server over a single TLS-encrypted connection. One connection per site. If the WAN link drops temporarily the probe keeps monitoring locally and syncs when connectivity returns, so uptime tracking and performance metrics continue uninterrupted at branch offices, manufacturing sites, or remote data centers.

Extended Protocol Support

What doesn't fit the standard protocols gets covered here. HTTP and HTTPS sensors query REST APIs for cloud platforms like Azure, SaaS applications including Microsoft 365, and custom web services, tracking uptime, latency, and endpoint health. IPMI and Redfish go below the OS entirely, monitoring server hardware at the baseboard level: temperature, fans, and power supplies, without requiring OS access. In OT environments, Modbus, MQTT, and OPC UA sensors reach PLCs, SCADA systems, and IoT devices that have no concept of a monitoring agent. Most environments have at least one corner that standard protocols don't reach cleanly. That's what this layer is for.

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Manual Monitoring vs. Agentless PRTG Monitoring: See the Difference

Capability	Manual / Ad-Hoc Monitoring Manual / Ad-Hoc Monitoring	PRTG Agentless Monitoring PRTG Agentless Monitoring
Setup Time	Manual / Ad-Hoc Monitoring Hours per device: manual CLI or GUI checks	PRTG Agentless Monitoring Minutes for entire network: auto-discovery creates sensors automatically
Ongoing Management	Manual / Ad-Hoc Monitoring Repetitive manual checks, no alerting	PRTG Agentless Monitoring Continuous automated polling with configurable alerting
Performance Impact	Manual / Ad-Hoc Monitoring Varies (heavy if using manual scripts repeatedly)	PRTG Agentless Monitoring Very low (SNMP, Flow, Ping) to minimal (WMI, SSH)
Historical Data	Manual / Ad-Hoc Monitoring Must manually log and store	PRTG Agentless Monitoring Automatic data retention with configurable intervals
Multi-Site Visibility	Manual / Ad-Hoc Monitoring Separate checks per location	PRTG Agentless Monitoring Centralized dashboards for all remote probes

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”Adopting PRTG has been like going from being in the dark to being in the light. Before, we had limited visibility into what was happening in the infrastructure and in the network. Now, however, thanks to the comprehensive dashboard and real-time notifications, we receive constant updates on the status of facilities and services, and our way of working has gone from passive to proactive.”

Luca Meneghesso, Senior IT infrastructure and Security Specialist

Banca Profilo

”GESAC increasingly focuses on innovation to improve the quality of services offered and the experience of passengers handled every day by Naples Airport. Thanks to PRTG, we finally have unified, automatic, and continuous monitoring of the airport network and can guarantee quick and timely interventions.”

Domenico Ciervo, GESAC ICT Manager

Naples International Airport

”As an international company, PRTG is ideal for us. If something went down half way across the world, we wouldn’t be woken up – we can rely on PRTG to identify the problem and alert us before it occurs – enabling the right person, in the right time zone to resolve the problem. At the end of the day, if we’re to provide an internal network experience for our employees that meets expectations, we need a tool like PRTG to be successful.”

Barry Kelly, Systems Engineer

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Paessler PRTG Network Monitor licenses & pricing

Choose the PRTG Network Monitor subscription that's best for you.

License Name	Price	License Details	Get started	Pricing Details
PRTG 500	^$200	per month paid annually	Buy now Buy now	Enough to monitor multiple aspects of 50 devices
PRTG 1000	^$358	per month paid annually	Buy now Buy now	Enough to monitor multiple aspects of 100 devices
PRTG 2500	^$742	per month paid annually	Buy now Buy now	Enough to monitor multiple aspects of 250 devices
PRTG 5000	^$1,300	per month paid annually	Buy now Buy now	Enough to monitor multiple aspects of 500 devices
PRTG 10000	^$1,642	per month paid annually	Buy now Buy now	Enough to monitor multiple aspects of 1000 devices

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Agentless Monitoring: Frequently Asked Questions

What's the difference between agentless monitoring and agent-based monitoring?

The core difference is where the work happens. Agentless monitoring uses native protocols already present on your devices: SNMP, WMI, SSH, Flow. Nothing gets installed. Agent-based monitoring puts a software process on each device that collects and transmits data back to the monitoring server. PRTG uses agentless methods by default. That removes deployment overhead, and it also means network devices that simply can't run agents are still covered rather than left as blind spots. Performance impact on monitored systems stays minimal. For Windows servers where both approaches are technically possible, you choose based on what your environment actually needs.

Can PRTG monitor devices behind firewalls without opening many ports?

That's specifically what remote probes are for. Each probe installs at a location behind the firewall, monitors local devices using agentless protocols, and sends aggregated data back to the central PRTG server over a single outbound TLS-encrypted connection. One connection per site, not one per device. The architecture handles branch offices, DMZs, and partner networks the same way. Segmented environments with strict firewall policies are the exact scenario remote probes were built for.

Does agentless monitoring work for both IT and OT environments?

Yes, though the protocol sets are different. On the IT side PRTG uses SNMP, WMI, SSH, NetFlow, and HTTP. OT environments get covered through Modbus, MQTT, and OPC UA. Both run from the same PRTG instance, so you're not maintaining separate monitoring systems for the server room and the factory floor. Worth noting that OT device behavior can differ from IT expectations around polling intervals and response times, so sensor configuration sometimes needs adjusting for industrial environments specifically.

What credentials does PRTG need for agentless monitoring?

Depends on the protocol. SNMP v1 and v2c use community strings. V3 needs user credentials with authentication and privacy settings configured on both sides. WMI requires Windows credentials with WMI access, typically a domain or local admin account. SSH uses Linux or Unix credentials, key-based authentication included. Cloud services and APIs take API keys. You set credentials at device or group level and PRTG inherits them downward, so you're not entering them per device. No software gets installed regardless of which protocol you're using.

How does PRTG's agentless monitoring handle high-security environments?

Several layers. SNMPv3 adds encryption and authentication on top of the standard protocol. SSH supports key-based authentication rather than passwords. API queries go over HTTPS, probe-to-server communication uses TLS, and credentials sit encrypted in the PRTG database. For environments where agentless access to certain zones is restricted entirely, remote probes can live inside those zones and transmit only aggregated metrics outbound through the encrypted connection. Not raw device data. That distinction matters specifically in environments with strict data handling requirements, where what leaves a zone is as important as how it leaves.