The more established network monitoring tools have become, the higher the expectations of enterprises have risen. Companies from SME’s to multinational organizations are demanding a seamless infrastructure monitoring experience. Agentless monitoring has emerged as one of the most efficient methods for managing enterprise networks. In this article we’re going to look at what agentless monitoring is, and the best agentless monitoring tools.

We get into a lot of detail on each of the tools below, but in case you are after a quick list and free trial links, here is our list of the best agentless monitoring tools:

  1. SolarWinds Network Performance Monitor (FREE TRIAL) An SNMP-based network monitor that communicates with network devices to maintain system health.
  2. SolarWinds Server & Application Monitor (FREE TRIAL) A premium monitoring tool that includes 1,200 application monitoring templates. Installs on Windows Server, but will monitor Linux servers as well.
  3. Paessler PRTG Network Monitor A combined network, server, and application monitoring system that can be customized by choosing which monitors to implement.
  4. Site24x7 Agentless Server Monitoring A cloud-based tool that monitors IT infrastructure, application, and users in either an agent-based or agentless architecture. Agents available for Windows, Linux, Free BSD, and Solaris.
  5. ManageEngine OpManager A network monitor that uses SNMP to monitor network device health. Installs on Windows Server and Linux.
  6. WhatsUp Gold A network monitoring tool that can be extended to include server and application monitoring.

What is Agentless Monitoring?

Agentless monitoring is a form of network monitoring where a monitor collects performance metrics from devices without needing to install a software agent on the devices or servers being monitored. Agentless monitoring is popular because it allows companies to avoid the challenges of installing software agents on servers as they would have to do with an agent-based monitoring approach.

Agentless Monitoring vs Agent-based Monitoring 

While agentless monitoring is the more popular method for monitoring networks today, it isn’t necessarily better than agent-based monitoring. Agentless monitoring is easy to manage but agent-based monitoring obtains more detailed data from systems. The reason for this is because software and hardware vendors produce custom agents that accommodate network monitoring tools with more information.

However, the problem with the agent-based monitoring approach is that it doesn’t scale well within large organizations. Attempting to install software agents across multiple servers becomes complex and difficult to manage very quickly. Agentless monitoring gives you more flexibility with the tools you can use.

The best agentless monitoring tools

1. SolarWinds Network Performance Monitor (FREE TRIAL)

SolarWinds Network Performance Monitor is a network monitoring platform designed for those with scalability in mind. You can monitor devices developed by a range of vendors through the dashboard which displays a status overview of all connected devices and servers. There are also more advanced views like NetPath that show a topological network path. NetPath shows you how devices connect to each other and can be used to diagnose problems that you might have missed from the dashboard.

For larger networks, there are a variety of features that support monitoring at scale. One of these is the Enterprise Operations Console which collects performance data from SolarWinds servers and shows it on a centralized dashboard. The EOC dashboard is more comprehensive than the standard dashboard and shows you sections such as Network Devices, Enterprise Nodes, Orion Site Status, Hosts, Enterprise Servers, Applications, Cisco Gear, and All Alerts.

SolarWinds Network Performance Monitor uses an alerts system that works by setting performance baselines that determine the trigger conditions for notifications. Alert conditions are also configurable based on a variety of trigger conditions. Options for trigger conditions include high response time, host CPU utilization, and Alert me when a transaction goes down.

As an agentless monitoring solution, SolarWinds Network Performance Monitor checks all the boxes as a responsive and easy to use solution for SME’s and large organizations. The price of SolarWinds Network Performance Monitor starts at $2,995 (£2,390). You can download the 30-day free trial.

SolarWinds Network Performance Monitor Download 30-day FREE Trial

2. SolarWinds Server and Application Monitor (FREE TRIAL)

SolarWinds Server & Application Monitor is a server and application monitoring tool with over 1200 monitoring templates for Windows and Linux applications. The installation is fast-track so you can be up and running in less than an hour. To help configure application monitors there is a Component Monitor Wizard to set up different sensors you can use to monitor your network. The dashboard includes a mixture of tabs on application status and an overview of application health.

Monitoring application dependencies with SolarWinds Server & Application Monitor is easy because you can automatically discover applications and servers. Once applications are discovered they are then added to a map of dependencies so you can see how your infrastructure is constructed.

In terms of alerts, SolarWinds Server & Application Monitor uses custom alert thresholds to identify deviations from normal application behavior. For instance, you can configure alerts to be activated based on response time, CPU utilization, and storage space. There is also the option to create reports to take a closer look at what’s going on.

Overall SolarWinds Server & Application Monitor is an excellent tool for those enterprises that require an agentless monitoring tool with a focus on applications. SolarWinds Server & Application Monitor starts at a price of $2,995 (£2,390). There is also a 30-day free trial.

SolarWinds Server & Application Monitor Download 30-day FREE Trial

3. Paessler PRTG Network Monitor

Paessler PRTG Network Monitor is an agentless network monitoring tool with a modern user interface. PRTG Network Monitor uses SNMP, WMI, NetFlow, IPFIX, jFlow, sFlow, and packet sniffing to pull information from connected devices. The software also has an auto-discovery feature which finds connected devices by IP range. Once devices are added to the monitoring environment they can then be monitored in the form of a network map, which details the relationships between the systems.

The dashboard experience delivered by PRTG Network Monitor is very high quality. The tool displays live network data in real-time through customizable dashboards that provide a range of graphs and charts. There are over 300 different map objects for you to choose from so you have complete control over how you monitor your network.

For on-premises licenses, PRTG Network Monitor includes a single failover. The single failover means that if the central node of a cluster goes down another node will step in and resume its responsibilities. The free failover helps to ensure that the network stays available even if there is an outage.

PRTG Network Monitor is available as a free or paid product. Paid versions of PRTG Network Monitor start at $1,347 (£1,075) for five sensors and one server installation up to $12,912 (£10,308) for unlimited servers and one server installation. There is also an unlimited version with five server installations that costs $50,523 (£40,337). You can download the 30-day free trial version.

Paessler PRTG Network Monitor Download 30-day FREE Trial

4. Site24x7 Agentless Server Monitoring

Site24x7 Server Monitoring is available with and without agents. The agentless monitoring service can pick up a lot of information from your network and servers. However, the agent-based version can gather a lot more categories of data.

The tool monitors IT infrastructure, applications, and end-users. The network monitoring systems in the package don’t need agents to be installed because they can query information gathered by the pre-installed device agents that are resident on all network equipment as an industry standard. Monitoring other equipment, such as servers, without agents is problematic.

Site24x7 can function without agent software being installed on the server, but there are a lot fewer metrics that the agentless version can gather. For example, it is easy for the remote server to measure the roundtrip time (RTT) to the server being examined. However, gathering information on the operations of the server requires queries to be executed on that server. These data-gathering functions are the reason that remote monitors rely on a piece of software running on the target server.

The agent-based and agentless versions of Site24x7 use the same console. However, they are set up in different ways. With the agent-based system, agents can be installed in bulk on Windows and Linux servers. The agentless version needs an IP address or a range of addresses to be entered into the console’s settings.

Site24x7 is a cloud-based service, available in four editions. The Free version is limited to monitoring five servers. Any of the four paid versions are available on a 30-day free trial.

5. ManageEngine OpManager

ManageEngine OpManager is an agentless monitoring tool with over 2000 network performance monitors. With ManageEngine OpManager you can monitor devices, servers, and virtualized services through customizable dashboards with over 200 performance widgets available to choose from. In terms of metrics, you can monitor availability, packet loss, response time, CPU utilization, memory utilization, and disk utilization.

Managing performance monitors can be done through the Performance Monitors page. Here you can choose to Add Monitor or Associate an existing Monitor with a particular service. Monitors you can add include Memory Utilization, Active Session Count, and Firewall CPU Utilization. Having all of this information in one place enables greater control over what is being monitored.

The software offers a range of support for server monitoring as well. Vendors supported by ManageEngine OpManager include Windows, Linux, Solaris, Unix, VMWare, and more. Server performance is monitored in real-time with metrics such as server availability, health, and CPU utilization tracked by the program.

ManageEngine OpManager is available on Windows and Linux. There is a free edition that allows you to monitor up to three devices. There are three paid versions of ManageEngine OpManager that you can purchase: Standard, Professional, and Enterprise.

The standard/professional versions support up to 1,000 devices from a single server and the Enterprise version supports up to 10,000 devices and 100,000 interfaces. However, you’ll need to contact the sales team directly to get a quote. You can download the free trial version of ManageEngine OpManager via this link here.

6. WhatsUp Gold

WhatsUp Gold is an agentless network monitor with auto-discovery. The platform automatically discovers devices and applications which you can then monitor through the dashboard or the map view. The product has a customizable dashboard with color-coded device status symbols. The network map shows you a topological perspective with color-coded devices where systems are classified as Up, Down, Maintenance, and more.

The application monitoring capabilities of WhatsUp Gold are also very detailed. The Application Performance Monitoring plug-in allows the user to monitor web transaction scripts and response times to identify performance issues. There are also monitoring profiles included out-of-the-box for Microsoft Exchange, SQL, SharePoint, and Active Directory.

The tool has a Virtual Monitoring plug-in to enable the monitoring of virtualized environments. The Virtual Monitoring plug-in takes performance data from VMware and Hyper-V resources to make sure your visibility reaches right down to the hypervisor level. The alerts system notifies you if there are any performance issues you should be aware of.

To view the price of WhatsUp Gold you’ll have to request a quote from the company directly. Packages support from 1-25 devices right up to 2500-plus devices. The wide range of devices supported makes WhatsUp Gold ideal for larger enterprises that rely on scalability. There is also a free trial version that you can download via this link here.

Agentless Monitoring: Infrastructure Monitoring for the Future 

In scalable enterprise environments, agentless monitoring is a necessity. It provides the user with the flexibility to incorporate disparate vendors into their network while cutting down on administrative burdens. The agent-based approach of installing software agents on servers still has a place, but it doesn’t offer the malleability that agentless monitoring tools do.

Tools like SolarWinds Network Performance Monitor and Paessler PRTG Network Monitor have become some of the leading network monitoring tools. Agentless network monitoring tools that incorporate auto-discovery features and customizable dashboards drive a more seamless administrative experience that helps identify performance issues at all levels of the network.

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