Frequently asked questions

You've got questions. We've got answers.

Learn about OpenNMS, distribution differences, requirements, integrations, and subscriptions.

What is OpenNMS?2023-01-09T15:40:05-05:00

OpenNMS is a scalable and highly configurable open-source network management platform with comprehensive fault, performance, and traffic monitoring. It easily integrates with your core business applications and workflows to monitor and visualize everything in your network. OpenNMS is available as two different, completely open source, distributions.

What can OpenNMS monitor?2023-01-07T17:40:12-05:00

Almost anything. There are a lot of built-in definitions to monitor and/or collect performance metrics on a variety of systems. If your device is not on this list, there may be some community-contributed configurations available—or you can easily create your own.

  • ICMP/Ping
  • DNS
  • DHCP
  • HTTP(S)
  • FTP
  • JDBC
  • SNMP
  • SMTP
  • SSH
  • WMI
  • WSMan
  • Cassandra
  • MySQL
  • PostgreSQL
  • MS SQL
  • Oracle
  • VMware
  • Elasticsearch
  • Windows and/or Linux servers
  • NSClient
  • Prometheus
  • 3Com
  • APC
  • Brocade
  • Cisco
  • Dell
  • ExtremeNEtworks
  • F5
  • Fortinet
  • HPE
  • IBM
  • Juniper
  • Mikrotik
  • Netapp
  • Palo Alto
  • Sonicwall
  • ...and many more
What’s the difference between Horizon and Meridian?2023-01-09T16:30:26-05:00

OpenNMS Meridian and Horizon are both fully open source and licensed under the AGPLv3. What's the difference?

Meridian is an optimized, stable version of OpenNMS, via a subscription, that maximizes the platform’s value and minimizes the effort required to maintain it. Meridian is curated by The OpenNMS Group for production environments. Matured features from Horizon are incorporated into an annual major Meridian release and updates are designed to be much easier for Meridian.

Horizon is available to download from our repository on Github for free and releases early and often. Focused on innovation, Horizon contains the latest updates to OpenNMS; however, not all features may be production-ready.

What are the requirements for a basic OpenNMS installation?2023-01-07T17:39:08-05:00

For a single-server proof-of-concept with up to 100 "average" nodes, a good starting point might be:

  • Red Hat Enterprise Linux 8 or CentOS 8 (simplifies dependencies versus Red Hat Enterprise Linux 7)
  • 4 CPU cores
  • 4GB physical memory
  • 100GB disk, preferably SSD

We define a node as any device or service attached to your network.

What’s the base operating system required to install OpenNMS?2023-01-19T15:29:40-05:00

OpenNMS Meridian requires one of the following operating systems. See the latest Meridian release notes for information about OS support changes.

Operating System Compatible Versions (64-bit):

  • Red Hat Enterprise Linux 7.x & 8.x
  • CentOS 7.x
  • CentOS Stream 9.x

OpenNMS Horizon requires one of the following operating systems. See the latest Horizon release notes for information about OS support changes.

Operating System Compatible Versions (64-bit):

  • Red Hat Enterprise Linux: 7.x, 8.x, 9.x
  • CentOS: 7.x
  • CentOS Stream: 9.x
  • Debian: 9 - 11
  • Ubuntu: 20.04 LTS
What database(s) does OpenNMS use?2023-01-06T19:28:30-05:00

The core of OpenNMS uses PostgreSQL. It can be on the same server for smaller deployments, but we recommend using a separate cluster for better performance in larger networks.

Depending on which features you configure, you may require other data stores. Our telemetry/flow collection service requires an Elasticsearch cluster. By default, performance metrics are stored in RRD files, and there is an option to replace those with a Cassandra or ScyllaDB cluster.

What if I have multiple sites with devices to monitor?2023-01-07T17:39:53-05:00

Not a problem.

Deploy OpenNMS in your primary site and then set up our Minion appliance component at remote sitesThe core server will control the Minions to monitor nodes at that site and all collected data will be rolled up from the Minion to the core OpenNMS instance for a centralized view of your network. If you're collecting flow data for multiple sites, we also have a Sentinel component that can provide horizontal scaling to offload flow processing from your core server. 

What other systems can OpenNMS integrate with?2023-01-07T17:41:02-05:00

In addition to a robust REST API that allows you to easily get data in and out of OpenNMS, we have a direct integration with many other systems and protocols (too many to list here). These include, but are not limited to:


  • Email
  • Slack
  • Mattermost
  • Custom scripts (send to your own custom script/webhook)


  • JIRA
  • Remedy
  • TSRM


  • Grafana

Telemetry/Flows (requires an Elasticsearch cluster)

  • BMP BGP Monitoring Protocol
  • Junos Telemetry Interface
  • Netflow v5/9/IPFIX/sFlow
  • Cisco NX-OS Telemetry
  • Graphite Telemetry
  • OpenConfig Telemetry

Time Series Storage

  • RRD/JRobin
  • Newts (uses a Cassandra cluster)
How many devices and number of alarms can be supported per instance?2023-01-07T17:18:37-05:00

An instance is each individual installation of Meridian or Horizon. While there is no built-in limit on either, the answer comes down to individual network environments versus a simple count of nodes and alarms.

Scalability in an enterprise monitoring system rests on the amount of work required to monitor the inventory, which is measured in a more granular way.

Here are just a few things to consider:

  • Port Monitoring: Yes/No? If yes, how many ports to check?
  • Availability monitoring: Yes/No? If yes, how many IP services to monitor with synthetic transactions (ICMP, HTTP, DNS, etc.)?
  • Performance monitoring: Yes/No? If yes, how many metrics per device in the inventory to collect?
  • Threshold monitoring: Yes/No? If yes, how many IP services and performance metrics to threshold?
  • Flow monitoring: Yes/No? If yes, how many flows per second per device?

Also factor in the frequency of each check and metric collection as well as the desired data retention period. The hardware or VM where you install OpenNMS and the various messaging and persisting dependencies impact the scalability of the deployment as well.

Is there artificial intelligence/machine learning (AI/ML) available for OpenNMS?2023-06-09T16:48:58-04:00

OpenNMS ALEC (Architecture for Learning Enabled Correlation) is our framework that uses artificial intelligence and machine learning to group related alarms so you can better manage the more complex situations they might represent.

ALEC uses temporal clustering techniques, machine learning algorithms, and deep-learning technology with topology data to group related alarms into a high-level situation. It detects network pattern behaviors and generates early warning signals for proactive remediation. It applies statistical and machine learning techniques to multi-dimensional input signals.

Note: ALEC is a community plugin. As such, it's available to all users and customers, but does not qualify for SLA-backed support unless specific arrangements for an exception are in place with OpenNMS Support.

What is Minion Virtual Appliance?2023-01-07T17:25:02-05:00

A Minion Virtual Appliance is a virtual device that runs the OpenNMS Minion component to collect data from distributed locations and forward them to your OpenNMS server. You can deploy, configure, and manage Minion appliances through the cloud-enabled OpenNMS Portal.

See the Minion Appliance Data Sheet for more information.

Is the Minion Virtual Appliance free?2023-01-06T14:33:18-05:00

Minion Virtual Appliance is a subscription-based service. The subscription includes the number of appliances you purchase and the right to access the Portal for one year. For more information, see the pricing page for details.

How do I access the virtual appliance?2023-01-07T17:22:38-05:00

Log in to the cloud-enabled OpenNMS Portal to deploy, configure, and manage Minion Virtual Appliances.  

Is there a hardware version of the Minion Virtual Appliance?2023-01-07T17:24:08-05:00

Currently, the Minion Virtual Appliance is only available as a virtual device.  

Do I have to upgrade my current OpenNMS core to use the Minion Virtual Appliance?2023-01-07T17:49:46-05:00

That depends. The Minion Virtual Appliance works with OpenNMS Horizon 29.0+ or OpenNMS Meridian 2021.1.5+. You must upgrade your core if you are running an earlier version.

How many Minions can I run on each virtual appliance?2023-01-07T17:23:30-05:00

Each virtual appliance runs one Minion.  

How secure is the appliance portal?2023-01-07T17:21:24-05:00

We use Okta for user authentication into the OpenNMS Portal and Appliance Service.

The Minion appliance allows only cryptographically signed software to run, which helps defend against unauthorized code, such as malware or unapproved applications. OpenNMS uses Docker Notary technology to sign our Minion software, and Ubuntu Core uses snap packages to sign operating system software.

Docker and Ubuntu snaps both use containerization technologies to isolate and protect applications that run within the Minion appliance. This prevents applications from inadvertently or intentionally harming each other or the underlying Ubuntu/Linux Core operating system. These features make containerized software more secure, resilient, and stable than traditional software packages.

Updates to software used in Minion appliances can be automatically or manually initiated when new versions of Minion Docker images or Ubuntu snaps become available for download. Using the technologies described above, appliances will install only cryptographically signed, OpenNMS-approved updates.

OpenNMS development and QA engineers are skilled in secure software engineering and testing techniques. In addition to in-house testing, OpenNMS engages outside security assessment firms to test various components in the Appliance Service and Minion images. If security issues are discovered, they are prioritized for remediation, based on the associated risk, and then re-tested when a fix is implemented.

Is there a development kit? What development is permitted?2023-01-07T17:44:23-05:00

Yes. OpenNMS is 100% open source and all tooling is available via open source resources.

We provide all the build tooling for developing against the Java APIs. There's also a nice API for developing plugins that doesn't require a full rebuild of OpenNMS—or even starting or stopping the system to install the plugin. 

What continuous integration/continuous deployment (CI/CD) practices do you use?2023-01-07T17:42:14-05:00

We use CircleCI to host our CI/CD environment. Our entire platform is based on test-driven development, with as much (or more) software written in tests as we have in actual testing software. All of this is verifiable, since the tests, code, and entire CI/CD pipeline are all open source. The build pipeline from issue to pull request to merging to testing to packaging is all process-driven and publicly referenceable in the tools that we use: 

  • Jira: Issue management and agile development (weekly sprints) 
  • GitHub: Source code management and GitHub pull request process flow with Jira and CircleCI 
  • CircleCI: Our build toolchain that runs a full suite of tests: Unit, integration (mock environments), system (dockerized live systems), and smoke (web UI).

How do you ensure that there are no regressions with new code additions? (And is this automatic?) 

We have been doing test-driven development in the project now for more than 10 years, and yes, the intent is to be automatic.

Here's a link to the CI/CD toolchain: https://circleci.com/gh/OpenNMS/opennms.

How do you measure code coverage for tests? 

We integrate with SonarCloud.

Here's a report on today's latest code in active development: https://sonarcloud.io/component_measures?id=OpenNMS_opennms&metric=coverage# 

What does one subscription per management server mean?2023-01-11T20:42:09-05:00

A subscription provides access to the software repository for initial installation and updates. Each instance of the software you are running requires one subscription. The instance places no limit on the number of users or the number of managed entities/elements.

What licensing models do you support (per instance or per monitoring object or a combination)?2023-01-07T17:37:47-05:00

OpenNMS features unlimited inventory. OpenNMS Meridian, our enterprise-ready release, is limited only per instance. Installing the software on multiple instances requires a subscription fee per instance. You may monitor as many nodes as possible with each instance.

What do you mean by “instance”?2023-01-07T17:45:19-05:00

An instance is each individual installation of Meridian or Horizon. 

Do you have any vulnerability reports produced by standard vulnerability tools?2023-01-07T17:42:50-05:00

In addition to the services that GitHub and SonarCloud provide, the OpenNMS community also reports on vulnerabilities. With thousands of users and companies running the software, many in DoD, we have a lot of eyes and vulnerability scans on the software. 

What is a support ticket?2023-01-09T15:51:19-05:00

A support ticket can describe an incident report, problem, or issue with OpenNMS software. For each of these, we request that you open a ticket in the OpenNMS support portal (https://support.opennms.com). Our support team will triage the issue and decide the next course of action.

You may want to open a support ticket for any of the following scenarios:

  • You need help with an issue you found during an installation or upgrade.
  • You have a general question about something you encountered during the operation of the OpenNMS application.
  • You found a bug in our application.
  • You want to suggest an enhancement to our application.

To open a support ticket, log into the OpenNMS support portal at https://support.opennms.com. Once the OpenNMS support team receives a support ticket, they'll review and prioritize it to make sure it gets the proper attention. The ticket will then be assigned to a support agent who will start working on it and make sure it's resolved within the associated Service-Level Agreement (SLA).

If a support ticket requests a bug fix or an enhancement, it will be routed to the appropriate OpenNMS team for review and assessment. If a Jira ticket is created to handle this, that ticket number will be added to the support ticket as well. We'll provide a summary of the resolution on the ticket. Note that a bug fix will have an SLA associated with it, but an enhancement request does not.

When should I open a support ticket?2023-01-09T15:51:04-05:00

You should open a ticket in the OpenNMS support portal to address incident reports, problems, or issues with OpenNMS software. Or, you may have a general question or a request for product enhancements. Our support engineers are here to help.

Support tickets are how we share issues and related information with our customers (like logs and configurations), ask questions, provide suggestions, and capture progress and resolution histories. We want to be well-connected with you as a customer to ensure your success—as well as our own.

If in doubt, create a support ticket and we'll reach out.

To open a support ticket, log into the OpenNMS support portal at https://support.opennms.com. Once the OpenNMS support team receives a support ticket, they will review and prioritize it to make sure it gets the proper attention.

How do I open a support ticket?2023-01-09T15:50:54-05:00

Each authorized support contact in your company's support account should have received an email that specifies their individual login. This notification also includes a link to set their initial password and then log in to our support portal. Once the login is verified, these instructions apply to all logins.

Steps to open a case:

  1. Log in to your OpenNMS support account through https://support.opennms.com.
  2. Click “Submit a New Ticket”.
  3. Enter all the necessary details.
  4. Fill in all the required fields (marked with a *).
  5. Click "Submit."

You'll receive an email from our system letting you know your support ticket was created. This will also include the ticket number. All future conversations will occur through this ticket. You'll also receive notifications through email when a support agent updates or comments on your ticket.

What support packages do you offer?2023-04-26T19:35:13-04:00

We offer a variety of support packages, with different options based on your environment and needs. Each package allows for a certain number of Meridian cores, Minions, support for a range of components, support contacts, and more.

We also offer expanded support hours and associated SLAs with our 24/7 support add-on.

See our pricing page to learn more.

Do you offer per-incident support?2023-01-07T17:17:49-05:00

We do not currently offer per-incident support.

Our subscription plans offer more than support, though. They give you access to Meridian, the hardened, tested, enterprise version of OpenNMS. They also give you the ability to contact our support engineers to ask questions, resolve incidents, report bugs, and request features and enhancements.

What Helm support do you offer?2023-01-09T15:50:28-05:00

What we support:

  • Configuration of OpenNMS data sources and data visualizations included with Helm
  • Best-effort diagnostics of the Grafana platform based on general knowledge

What we don’t support

  • Grafana itself (diagnosing Grafana failures or scalability, fixing Grafana bugs, and so on)


Note: The Helm referred to here is an application that lets users create flexible dashboards to interact with data stored by OpenNMS.

Note: We'll give our best effort to help determine if a problem exists—in your environment—with a technology stack that OpenNMS uses. We'll often make suggestions based on our exposure and experience with these applications and integrations.

Our plans do not cover support for Linux, PostgreSQL, Grafana, Cassandra, Kafka, or Elasticsearch.

What Flow / Streaming telemetry support do you offer?2023-01-09T15:50:21-05:00

What we support:

  • Configuration and diagnostics of the flow and streaming technology listeners in the OpenNMS Core and Minion
  • Customization of visualizations in the Helm application
  • Support for how to set up OpenNMS to use Elasticsearch (ES) and configuration to the point of the Elasticsearch API

What we don’t support:

  • Kafka or Elasticsearch


Note: We'll give our best effort to help determine if a problem exists—in your environment—with a technology stack that OpenNMS uses. We'll often make suggestions based on our exposure and experience with these applications and integrations.

Our plans do not cover support for Linux, PostgreSQL, Grafana, Cassandra, Kafka, or Elasticsearch.

What NewTS support do you offer?2023-01-09T15:50:12-05:00

What we support:

  • How to set up OpenNMS to use NewTS and OpenNMS configuration to the point of the Cassandra API

What we don’t support:

  • Direct support of Cassandra or ScyllaDB clusters (we may suggest only general knowledge and best-effort diagnostics)
What PostgreSQL support do you offer?2023-01-09T15:50:04-05:00


What we support:

  • Basic technical assistance such as setup, configuring access to the PostgreSQL database, and issues related to its interaction with the Meridian Core

What we don’t support:

  • Fixes for PostgreSQL bugs or making sure the database is sustained


PostgreSQL Cluster

What we support:

  • Help with configuration, advanced troubleshooting, diagnostics, and only maintenance related to the API handoff

What we don’t support:

  • Fixes for PostgreSQL bugs or making sure the database is sustained
What Kafka support do you offer?2023-01-09T15:49:47-05:00

What we support:

  • How to set up OpenNMS to use Kafka and configuration to the point of the Kafka API

What we don’t support:

  • Direct support of Kafka (we may suggest only general knowledge and best-effort diagnostics)


Note: We'll give our best effort to help determine if a problem exists—in your environment—with a technology stack that OpenNMS uses. We'll often make suggestions based on our exposure and experience with these applications and integrations.

Our plans do not cover support for Linux, PostgreSQL, Grafana, Cassandra, Kafka, or Elasticsearch.

What is the support for SDN or NFV?2023-01-07T17:41:52-05:00

We have integration with OpenDaylight and will soon complete the project for Cisco ACI.

NFV is on our roadmap. 

How can I help with my support issue?2023-01-09T15:49:09-05:00

Provide as much detail about your problem to help us understand what the actual issue might be and assess the area of the application that is causing the issue.

When possible, include the following in your ticket:

  • OpenNMS logs that may have been created
  • Configuration files
  • The severity of the issue

Use the following as a guideline for severity level:

Severity Description
Critical - Emergency OpenNMS application failure
Urgent Production is adversely impacted, but still functioning.
Production seems fine, but you see some odd behaviors.

(This is the severity for most support tickets.)
Non-urgent Non-production cases or questions on potential use cases
What are your support response SLAs?2023-01-09T15:48:58-05:00

Initial response

(Time to acknowledge the receipt of a support ticket and assign it to a support agent.)

Severity Essential Premier Premier+ 24/7
(Urgent tickets only)
Urgent 4 hrs 2 hrs 1 hr 15 min
High 24 hrs 24 hrs 4 hrs N/A
Medium 48 hrs 48 hrs 24 hrs N/A
Low 48 hrs 48 hrs 24 hrs N/A

Fixed time issues

(Time to resolve an issue—bug / security fix—that is logged with engineering.)

Severity Essential Premier Premier+
Urgent 60 days 60 days 60 days
High 90 days 90 days 90 days
Medium 90 days 90 days 90 days
Low N/A N/A N/A

Except for 24x7 plans, the listed SLA times are calculated within operating hours. For 24x7 plans, the customer can have 2 more contacts to create any emergency support tickets.

What are your support hours?2023-01-09T15:45:10-05:00

Our support hours are 7 a.m. to 7 p.m. EST Monday-Friday. 24/7 emergency support is also available as an add-on.


  1. If the Client has a 24/7 support contract and opens an urgent ticket because of application failure outside of the regular 7 a.m. - 7 p.m. EST hours, then it will be responded to within 15 mins and the support team will engage with the client to resolve the issue.
  2. If a high ticket is created at 6 p.m. EST, then it can be picked up anytime between 6 - 7 p.m. that day or 7 a.m. - 10 a.m. the next business day (4 business hours SLA).
What happens after I create a support ticket?2023-01-09T15:44:27-05:00

Once you've opened your ticket, we do the following to make sure we consistently deliver high-quality support:

  • All new tickets are assigned directly to OpenNMS technical support engineers.
  • Based on the situation and the severity, our team of support engineers will contact you within our committed response times.
  • Available 7 a.m. to 7 p.m. EST Monday - Friday, unless you have 24/7 support.

You also have access to the ticket, so if you feel like something is not being addressed correctly or you need to provide clarification, you can add those comments to the ticket. There may also be some offline exchange of information.

If the conversation necessitates it, we may request a quick call or screen share to understand the exact issue so we can provide a solution in a timely manner. If you have 24 x 7 support, then you can call the hotline provided to you in cases where a critical issue occurs during support off-hours.

How do I follow up on my ticket?2023-01-09T15:44:18-05:00

Stay on top of tickets by monitoring and responding to activity and updates in our ticketing tool at https://support.opennms.com.

Do you offer consulting services?2023-01-09T15:44:08-05:00

The OpenNMS Group is committed to providing outstanding and timely help for all of our support customers. In addition to helping our customers via support, we also offer dedicated consulting for more complex or time-intensive engagements. You can purchase consulting engagements in blocks of hours.

Our dedicated OpenNMS SME consultants schedule help sessions tailored to your needs.

For more information about consulting, reach out to your OpenNMS account manager or contact sales at [email protected].

Note that we also are committed to supporting our large and active open source community through our Discourse and Mattermost forums.

What is the difference between support and maintenance?2023-01-07T17:26:02-05:00

Almost all commercial software licenses include costs associated with maintenance on the license and support of the software. Maintenance is what's required to keep software updated to the latest version and get patch updates. Support is what's generally required for asking questions and getting SLAs on bug reports and fixes to issues. In commercially licensed software, these are often combined into a single line item, "Maintenance and Support". 

With OpenNMS, we've separated the notion of maintenance and support whereby you can get maintenance without paying for support. This gives you access to the private repositories for the software where you'll get all updates to the software. Support, which requires maintenance, is an additional set of offerings providing support at various levels and features. 

Where can I get community support?2023-01-09T15:43:33-05:00

After more than 20 years of open source development, the OpenNMS project has attracted a large community of active users. While you can count on us for high-quality support and committed response times, we also encourage you to be involved in our open source community—a rich source of information and resources on all things OpenNMS. Some of the most active contributors to the community channels are also members of our technical support team.

We have extensive official documentation available at https://docs.opennms.com/ for guidance on any specific subject within OpenNMS. We encourage and welcome your participation with documentation as well.

We have active community interactions on the following websites where we provide a lot of information about our products and also help with questions you may have:

Of course, as a customer, you don't need to rely on these communities for your critical or confidential support needs. For those needs, we strongly recommend using our support portal.

This might help some as well: Learn how to ask good questions.

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