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How agents work

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Created by Chris.Moyer, last modified by Anthony.Rinaldi_ret on Aug 24, 2016

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An agent is a software application that provides a communication channel between the Orion server and a monitored computer. Agents are used as an alternative to WMI or SNMP to provide information about your selected key devices and applications. These agents provide the following advantages:

  • Polls host and applications behind firewall Network Address Translation (NAT) or proxies.
  • Polls nodes and applications across multiple discreet networks with overlapping IP address space.
  • Provides secure encrypted polling over a single port.
  • Supports low bandwidth, high latency connections.
  • Polls nodes across domains where no domain trusts are established.
  • Provides full encryption between the monitored host and the Orion poller.
  • Monitors the server and installed applications during a network outage, regardless of whether the agent can communicate with the poller. When the poller connection is restored, the agent forwards the results of its monitoring data collected during the outage to the poller for processing. All data gaps are filled with the data collected by the agent.
  • The agent allows you to easily monitor servers hosted by cloud services, such as Amazon EC2, Microsoft Azure, Rackspace, or virtually any other Infrastructure as a Service (IaaS) provider.

All communications between the Orion server and the agent occur over a single fixed port. The communications are fully encrypted using 2048-bit Transport Layer Security (TLS) encryption. The agent protocol supports NAT traversal and passage through proxy servers that require authentication.

If an agent is used, all SAM application data is collected by the agent. You can choose to override this behavior. For example, if you assign an application template that uses a User Experience Monitor and you do not want to measure response time locally from the server where the application is installed, you can switch the application to poll without using an agent. This can be configured at both the application and template level.


Agent Communication can be deployed as either Agent Initiated or Orion Server initiated:

  • Agent initiated communication: The agent initiates communication with the server on the default port of 17778. This port must be opened on the server firewall so the agent can connect. No change to the agent firewall is required.
  • Orion Server initiated communication: The agent waits for requests from the server on the default port of 17790. This port must be opened on the firewall of the agent computer so the server can connect. No change to the server firewall is required.

Reports installed for use with the agent:

  • Agent Inventory
  • Agent Plugin Version

Tip: Use Orion Server initiated communication in DMZ environments or cloud scenarios such as Azure. Use agent initiated communication with a proxy to poll multiple computers within a single Azure cloud service.


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