Operations Manager agents
In System Center Operations Manager, an agent is a service that is installed on a computer that looks for configuration data and proactively collects information for analysis and reporting, measures the health state of monitored objects like a SQL database or logical disk, and execute tasks on demand by an operator or in response to a condition. It allows Operations Manager to monitor Windows, Linux, and UNIX operating systems and the components of an IT service installed on them, like a web site or an Active Directory domain controller.
On a monitored Windows computer, the Operations Manager agent is listed as the Microsoft Monitoring Agent service. The Microsoft Monitoring Agent service collects event and performance data, executes tasks, and other workflows defined in a management pack. Even when the service is unable to communicate with the management server it reports to, the service continues to run and queues the collected data and events on the disk of the monitored computer. When the connection is restored, the Microsoft Monitoring Agent service sends collected data and events to the management server.
The Microsoft Monitoring Agent service is sometimes referred to as the health service.
The Microsoft Monitoring Agent service also runs on management servers. On a management server, the service runs monitoring workflows and manages credentials. To run workflows, the service initiates MonitoringHost.exe processes using specified credentials. These processes monitor and collect event log data, performance counter data, Windows Management Instrumentation (WMI) data, and run actions such as scripts.
Communication between agents and management servers
The Operations Manager agent sends alert and discovery data to its assigned primary management server, which writes the data to the operational database. The agent also sends events, performance, and state data to the primary management server for that agent, which writes the data to the operational and data warehouse databases simultaneously.
The agent sends data according to the schedule parameters for each rule and monitor. For optimized collection rules, data is only transmitted if a sample of a counter differs from the previous sample by a specified tolerance, such as 10%. This helps reduce network traffic and the volume of data stored in the operational database.
Additionally, all agents send a packet of data, called a heartbeat, to the management server on a regular schedule, by default every 60 seconds. The purpose of the heartbeat is to validate the availability of the agent and communication between the agent and the management server. For more information on heartbeats, see How Heartbeats Work in Operations Manager.
For each agent, Operations Manager runs a health service watcher, which monitors the state of the remote Health Service from the perspective of the management server. The agent communicates with a management server over TCP port 5723.
The architecture of the UNIX and Linux agent differs from a Windows agent significantly. The Windows agent has a Health Service responsible for evaluating the health of the monitored computer. The UNIX and Linux Agent does not run a health service, instead it passes information to the Health Service on a management server to be evaluated. The management server runs all of the workflows to monitor operating system health defined in our implementation of the UNIX and Linux management packs:
- Network adapters
- Operating System
- Log files
The UNIX and Linux agents for Operations Manager consist of a CIM Object Manager (that is, CIM Server), and a set of CIM Providers. The CIM Object Manager is the “server” component that implements the WS-Management communication, authentication, authorization, and dispatch of requests to the providers. The providers are the key to the CIM implementation in the agent, defining the CIM classes and properties, interfacing with the kernel APIs to retrieve raw data, formatting the data (for example, calculating deltas and averages), and servicing the requests dispatched from the CIM Object Manager. From System Center Operations Manager 2007 R2 through System Center 2012 SP1, the CIM Object Manager used in the Operations Manager UNIX and Linux agents is the OpenPegasus server. The providers used to collect and report monitoring data are developed by Microsoft, and open-sourced at CodePlex.com.
This changed in System Center 2012 R2 Operations Manager, where UNIX and Linux agents are now based on a fully consistent implementation of Open Management Infrastructure (OMI) as their CIM Object Manager. In the case of the Operations Manager UNIX/Linux agents, OMI is replacing OpenPegasus. Like OpenPegasus, OMI is an open-source, lightweight, and portable CIM Object Manager implementation – though it is lighter in weight and more portable than OpenPegasus. This implementation continues to be applied in System Center 2016 - Operations Manager and later.
Communication between the management server and the UNIX and Linux agent is split into two categories, agent maintenance and health monitoring. The management server uses two protocols to communicate with the UNIX or Linux computer:
Secure Shell (SSH) and Secure Shell File Transfer Protocol (SFTP)
Used for agent maintenance tasks such as installing, upgrading, and removing agents.
Web Services for Management (WS-Management)
Used for all monitoring operations and include the discovery of agents that were already installed.
Communication between the Operations Manager management server and UNIX and Linux agent uses WS-Man over HTTPS and the WinRM interface. All agent maintenance tasks are performed over SSH on port 22. All health monitoring is performed over WS-MAN on port 1270. The management server requests performance and configuration data via WS-MAN before evaluating the data to provide health status. All actions, such as agent maintenance, monitors, rules, tasks, and recoveries, are configured to use predefined profiles according to their requirement for an unprivileged or privileged account.
All credentials referred to in this article pertain to accounts that have been established on the UNIX or Linux computer, not to the Operations Manager accounts that are configured during the installation of Operations Manager. Contact your system administrator for credentials and authentication information.
To support the new scalability improvements with the number of UNIX and Linux systems System Center 2016 - Operations Manager and later can monitor per management server, the new Async Windows Management Infrastructure (MI) APIs are available instead of WSMAN Sync APIs, which is in use by default. To enable this change, you need to create the new registry key UseMIAPI to enable Operations Manager to use the new Async MI APIs on management servers monitoring Linux/Unix systems.
- Open the Registry Editor from an elevated command prompt.
- Create registry key UseMIAPI under
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Microsoft Operations Manager\3.0\Setup.
If you need to restore the original configuration using the WSMAN Sync APIs, you can delete the UseMIAPI registry key.
Authentication on UNIX/Linux computer
In Operations Manager, the system administrator is no longer required to provide the root password of the UNIX or Linux computer to the management server. Now by elevation, an unprivileged account can assume the identity of a privileged account on the UNIX or Linux computer. The elevation process is performed by the UNIX su (superuser) and sudo programs that use the credentials that the management server supplies. For privileged agent maintenance operations that use SSH (such as discovery, deployment, upgrades, uninstallation, and agent recovery), support for su, sudo elevation, and support for SSH key authentication (with or without passphrase) is provided. For privileged WS-Management operations (such as viewing secure log files), support for sudo elevation (without password) is added.
For detailed instructions for specifying credentials and configuring accounts, see How to Set Credentials for Accessing UNIX and Linux Computers.
Authentication with gateway server
Gateway servers are used to enable agent-management of computers that are outside the Kerberos trust boundary of a management group. Because the gateway server resides in a domain that is not trusted by the domain that the management group is in, certificates must be used to establish each computer's identity, agent, gateway server, and management server. This arrangement satisfies the requirement of Operations Manager for mutual authentication.
This requires you to request certificates for each agent that will report to a gateway server and import those certificates into the target computer using the MOMCertImport.exe tool, which is located on the installation media SupportTools\ (amd64 or x86) directory. You need to have access to a certification authority (CA) which can be a public CA such as VeriSign, or you can use Microsoft Certificate Services.
System Center Operations Manager Agents may be installed by using one of the following three methods. Most installations use a combination of these methods to install different sets of computers, as appropriate.
- The discovery and installation of one or more agents from the Operations console. This is the most common form of installation. A management server must be able to connect the computer with RPC, and either the management server Action Account or other provided credentials must have administrative access to the target computer.
- Inclusion in the installation image. This is a manual installation to a base image that is used for the preparation of other computers. In this case, Active Directory integration may be used to automatically assign the computer to a management server upon the initial startup.
- Manual installation. This method is used when the agent cannot be installed by one of the other methods—for example, when remote procedure call (RPC) is unavailable because of a firewall. The setup is manually run on the agent or deployed through an existing software distribution tool.
Agents that are installed by using the Discovery Wizard can be managed from the Operations console, such as updating agent versions, applying patches, and configuring the management server that the agent reports to.
When you install the agent using a manual method, updates to the agent must also be performed manually. You will be able to use Active Directory integration to assign agents to management groups. For more information, see Integrating Active Directory and Operations Manager.
Agent deployment to Windows system
Discovery of a Windows system requires that the TCP 135 (RPC), RPC range, and TCP 445 (SMB) ports remain open and that the SMB service is enabled on the agent computer.
- After a target device has been discovered, an agent can be deployed to it. Agent installation requires:
- Opening RPC ports beginning with endpoint mapper TCP 135 and the Server Message Block (SMB) port TCP/UDP 445.
- Enabling the File and Printer Sharing for Microsoft Networks and the Client for Microsoft Networks services. (This ensures that the SMB port is active.)
- If enabled, Windows Firewall Group Policy settings for Allow remote administration exception and Allow file and printer sharing exception must be set to Allow unsolicited incoming messages from to the IP address and subnets for the primary and secondary management servers for the agent.
- An account that has local administrator rights on the target computer.
- Windows Installer 3.1. To install, see article 893803 in the Microsoft Knowledge Base
- Microsoft Core XML Services (MSXML) 6 on the Operations Manager product installation media in the \msxml sub directory. Push agent installation installs MSXML 6 on the target device if it is not already installed.
Agent deployment to UNIX and Linux system
In System Center Operations Manager, the management server uses two protocols to communicate with the UNIX or Linux computer:
- Secure Shell (SSH) for installing, upgrading, and removing agents.
- Web Services for Management (WS-Management) for all monitoring operations and include the discovery of agents that were already installed.
The protocol that is used depends on the action or information that is requested on the management server. All actions, such as agent maintenance, monitors, rules, tasks, and recoveries, are configured to use predefined profiles according to their requirement for an unprivileged or privileged account.
All credentials referred to in this section pertain to accounts that have been established on the UNIX or Linux computer, not to the Operations Manager accounts that are configured during the installation of Operations Manager. Contact your system administrator for credentials and authentication information.
By elevation, an unprivileged account can assume the identity of a privileged account on the UNIX or Linux computer. The elevation process is performed by the UNIX su (superuser) and sudo programs that use the credentials that the management server supplies. For privileged agent maintenance operations that use SSH (such as discovery, deployment, upgrades, uninstallation, and agent recovery), support for su, sudo elevation, and SSH key authentication (with or without passphrase) is provided. For privileged WS-Management operations (such as viewing secure log files), support for sudo elevation (without password) is supported.
Active Directory agent assignment
System Center Operations Manager allows you to take advantage of your investment in Active Directory Domain Services (AD DS) by enabling you to use it to assign agent-managed computers to management groups. This feature is commonly used in conjunction with the agent deployed as part of a server deployment build process. When the computer comes online for the first time, the Operations Manager agent queries Active Directory for its primary and failover management server assignment and automatically starts monitoring the computer.
To assign computers to management groups by using AD DS:
- The functional level of AD DS domains must be Windows 2008 native or higher
- Agent-managed computers and all management servers must be in the same domain or in two-way trusted domains.
An agent that determines it is installed on a domain controller will not query Active Directory for configuration information. This is for security reasons. Active Directory Integration is disabled by default on domain controllers because the agent runs under the Local System account. The Local System account on a domain controller has Domain Administrator rights; therefore, it detects all Management Server Service Connection Points that are registered in Active Directory, regardless of the domain controller’s security group membership. As a result, the agent tries to connect to all management servers in all management groups. The results can be unpredictable, thus presenting a security risk.
Agent assignment is accomplished by using a Service Connection Point (SCP), which is an Active Directory object for publishing information that client applications can use to bind to a service. This is created by a domain administrator running the MOMADAdmin.exe command-line tool to create an AD DS container for an Operations Manager management group in the domains of the computers it manages. The AD DS security group that is specified when running MOMADAdmin.exe is granted Read and Delete Child permissions to the container. The SCP contains connection information to the management server, including the server’s FQDN and port number. Operations Manager agents can automatically discover management servers by querying for SCPs. Inheritance is not disabled, and because an agent can read the integration information registered in AD, if you force inheritance for the Everyone group to read all objects at the root level in Active Directory, this will severely affect and essentially interrupt AD Integration functionality. If you explicitly force inheritance throughout the entire directory by granting the Everyone group read permissions, you must block this inheritance at the top-level AD Integration container, named OperationsManager, and all child objects. If you fail to do this, AD Integration will not work as designed and you will not have reliable and consistent primary and failover assignment for agents deployed. Additionally, if you happen to have more than one management group, all agents in both management groups will be multi-homed as well.
This feature works well for controlling agent assignment in a distributed management group deployment, to prevent agents from reporting to management servers that are dedicated to resource pools or management servers in a secondary data center in a warm-standby configuration to prevent agent failover during normal operation.
Configuration of agent assignment is managed by an Operations Manager administrator using the Agent Assignment and Failover Wizard to assign computers to a primary management server and secondary management server.
Active Directory Integration is disabled for agents that were installed from the Operations console. By default, Active Directory Integration is enabled for agents installed manually using MOMAgent.msi.
To understand how to install the Windows agent from the Operations console, see Install Agent on Windows Using the Discovery Wizard or to install the agent from the command line, see Install Windows Agent Manually Using MOMAgent.msi.
To understand how to install the Linux and UNIX from the Operations console, see Install agent on UNIX and Linux using the Discovery Wizard.
Review How to configure and use Active Directory Integration for agent assignment to learn how to create the container in Active Directory, configure agent failover assignment, and manage the configuration.