Continuous monitoring: Nagios, Icinga, Cacti, Omd

Quality is the main principle any service should be based on. Software development gains more and more popularity among services nowadays and quality of the product is usually the main point which guarantees the success of the project. A big number of developers can work on the project simultaneously and quality controlling and monitoring becomes a bigger challenge. One such challenge is to provide a comprehensive and brief visualization of the progress of software development and the progress of quality assurance.

The extensible and scalable architecture of products determines long-term solid business models and raises customer value. It makes continuous monitoring a mandatory factor during the development process.

Continuous monitoring means that the specific software monitors work of the server in order to identify weaknesses, slow or failing components of the server, and informs a system administrator about any issue. A great server monitoring provides a detailed information on the health of the server as well as performance benchmarking, alerting capabilities, detailed reporting, data visualization. Such statistic ensures smooth work of the server and respectively a flawless performance of the whole applications.

With the evolution of Agile and Lean methodologies, which always try to tune up the development process, now we have special software for continuous monitoring. Let’s go through some of them.



Nagios is certainly one of the oldest and mature open-source tools for server monitoring. It provides a centralized view of your entire IT infrastructure and detailed up-to-date status information and it helps to monitor system metrics, network protocols, applications, services, servers and network infrastructure. Identifying of infrastructure upgrades before failures occur is allowed by the trending and capacity planning graphs and reports. And scheduled downtime prevents alerts during maintenance windows.

It is free and open source, so as many open-source products it has a great support and a big community. Work with Nagios will be organized enough as it is well-documented.

Here are also some of pros:

  • Nagios monitors all main protocols (HTTP, FTP, SSH, POP3, SMTP, SNMP, MySQL, etc);
  • Alerts in e-mail and/or SMS;
  • Multiple alert levels (such as ERROR, WARNING, OK);
  • “Flapping” detection;
  • Automatic topography display;
  • Completely stand-alone, no other software needed;
  • Web content monitoring;



Originally a fork of Nagios, now Icinga is a complete re-written extensible monitoring system which checks the availability of your infrastructure resources with notifications for outages.

Adding a GUI, additional database connectors and a REST API to allow integration of extensions without complication modification of the application core improved Icinga and gave it new possibilities. Moreover, Icinga provides clear-cut, object-based configuration, clever commands & runtime macros, apply & assign attributes, dynamic notifications.

A brief of Icinga’s selling points:

  • Objects (checks, dependencies, etc) can be created using expressions with conditionals which reduces the need for boilerplate copy+paste config;
  • Has good support for alert dependencies and reflected in dashboard;
  • Can run any monitoring plugin;
  • Has native support for graphite;



This open-source system monitoring solutions, which enables users to poll services at regular intervals to create graphs on resulting data using RRDtool. It is designed to be easy, while at the same time being powerful enough to be used in complex networks.

Cacti’s Web site describes the software as:

“A complete network graphing solution designed to harness the power of RRDTool‘s data storage and graphing functionality. Cacti provides a fast poller, advanced graph templating, multiple data acquisition methods, and user management features out of the box. All of this is wrapped in an intuitive, easy-to-use interface that makes sense for LAN-sized installations up to complex networks with hundreds of devices.”

Cacti performs great results of monitoring network usage. The software is really scalable and it can manage to monitor very large networks while tracking diverse parameters. Cacti’s community is large and active, and development is proceeding at a rapid pace.

Cacti’s features include:

  • unlimited graph items
  • auto-padding support for graphs
  • graph data manipulation
  • flexible data sources
  • data gathering on a non-standard timespan
  • custom data-gathering scripts
  • built-in SNMP support
  • graph templates
  • data source templates
  • host templates
  • tree, list, and preview views of graph data
  • user-based management and security



The biggest fear of a web administrator is that for one reason or another the server that hosts will fail. To ensure the proper functioning of a website and to be able to act as soon as possible in the event of a failure, specific tools must be used to automatically control the status of a website, notifying us if it fails.

The main purpose of OMD is to take care of all the “dirty work” that requires using of applications such as Nagios, which must be compiled and implemented on the server manually, since this tool handles all this process autonomously, saving time and reducing error tolerance. OMD also allows us to easily dispose of the most up-to-date versions of these monitoring and control tools, since the versions included in the repositories are usually obsolete or not updated. Nagios plugins in a single environment help to create a homogeneous solution for monitoring all the IT systems from operating systems and web server infrastructure to SAP systems and databases (Oracle, DB2, Microsoft SQL Server).

Build on Nagios and coming with such software as Icinga, Shinken, NagVis, Check_MK, Thruk, Mod-Gearman, etc, Open Monitoring Distribution (OMD) provides extensive environments for consistent and continuous server monitoring.

OMD provides such features:

  • multiple instances per host;
  • separate omd user per instance;
  • script based tarball building;
  • simple creation of new sites;
  • supporting different omd version at the same time;
  • plattform independent paths;
  • speed optimizations.



The bottom line is that software market offers so many options available today, so it’s hard to evaluate which network monitoring tool is best for you. While it is important that your organization finds the product that best fits your needs—whether free or commercial—one thing to consider is that upper management might be more comfortable with a product that has a strong resume. Let’s take a look at a few free network monitoring options.

Would you like to find out more about the Continuous monitoring: Nagios, Icinga, Cacti, Omd? We’d be happy to answer your questions!

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