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Network Management With OpenNMS
Pages: 1, 2

The easiest way to get this stuff on a machine is to run, as root on your Linux box (which will need a minimum of 256MB of RAM, 50MB of free disk space under /opt, and a 500MHz processor or better), the command:

lynx -source | sh

And hope like hell you are running an RPM-capable system. Assuming you are, the online installer will check to see what is installed on your system and download the necessary prerequisites, including PostgreSQL, RRDTool, Tomcat, and some other incidentals. If you aren't using RedHat or Mandrake, or you aren't comfortable running a downloaded script with superuser privileges, there are instructions at the project Web site to help you build from source on your own. We'll leave that as an exercise to the reader.

Once installed, take a look in your /opt/OpenNMS directory. You should find a ./etc directory that includes a boatload of XML-based config files. While you could easily write a book on all of the configuration options, I'll focus on a few key parameters in three files:

  • discovery-configuration.xml
  • capsd-configuration.xml
  • poller-configuration.xml

First, discovery-configuration.xml controls what TCP/IP addresses will be discovered by the discovery process. The file supports the configuration of address ranges, which are defined with <begin> and <end> tags, and yes, you can configure multiple ranges (for multiple, non-contiguous IP networks), as well as exclude ranges (for eliminating discovery of DHCP ranges, as an example). And fortunately, the product ships with an example configuration that is pretty intuitive, so being the smart person you are, you'll figure this part out.

But while one might assume otherwise, the discovery process does nothing more than discover that an interface responded to a ping test. In fact, discovered interfaces are not even added to the database. Instead, the discovery process, when it discovers a new interface, simply generates an event that is picked up by the Capabilities Checking daemon, capsd. In turn, capsd scans the interface for the services it provides, and once a complete profile for that interface has been ascertained, it is then, and only then, committed to the database. Which means to get nodes into the database, you need to be able to manhandle (or womanhandle, as appropriate) the capsd-configuration.xml file.

The configuration file capsd-configuration.xml provides a comprehensive list of all the capsd plug-ins which will be doing the service scanning (we can safely leave these alone for now), as well as the TCP/IP address ranges we are interested in managing. This means that to complete discovery for even a simple environment, you will need to configure your network ranges in at least the discovery-configuration.xml and capsd-configuration.xml files. While a pain, this duality in configuration provides some subtle yet powerful default node-handling options.

Want to find out if new nodes are added to the network without automatically scheduling them for polling? Thought so.

Within the <ip-management> elements at the end of the file where the ranges are specified, you have the opportunity to set a policy to determine whether interfaces contained in that block will be managed (polled) or unmanaged (not polled). As before, you can specify ranges, as well as specific addresses. Pretty cool, huh? The pain associated with doing this configuration right one time is far outweighed by the fact that you shouldn't ever have to touch this again, or at least not until your network changes drastically or grows significantly.

Each of the <protocol-plugin> elements referenced earlier in that file carries its own complement of attributes and properties to allow you to get in and tune/tweak each plug-in in considerable depth. While it's quite handy, that tuning is well outside the scope of this article. Just know that it's there if you need it.

Finally, we have the poller-configuration.xml file, which controls the polling subsystem (duh). While sporting IP address ranges and file structures similar to the previous two config files we've looked at, this file is notably more complex. And as always, with complexity comes flexibility.

The poller-configuration.xml file is comprised of a series of <package> elements. These packages are functional groupings of TCP/IP address collections and services you wish to poll, along with specific configurations for those services. For example, if you wanted to monitor the entire Class C network with pings to interfaces once every five minutes, but wanted to poll all of the nodes with a fourth octet greater than 200 once every minute (convoluted, yes, but bear with me), you could create the following approximation:


<package name=?FiveMinutePings?>

<include-range begin=? end=?>

<service name=?ICMP? interval=?300000?>

<parameter key=?retry? value=?3?/>

<parameter key=?timeout? value=?3000?/>



<package name=?OneMinutePings?>

<include-range begin=? end=?>

<service name=?ICMP? interval=?60000?>

<parameter key=?retry? value=?3?/>

<parameter key=?timeout? value=?3000?/>




The only thing we've really done is create multiple <package> elements, and within each <service> element for ICMP, associate an interval attribute value of 60000 (which is the time between polls in milliseconds). Easy enough. For now, we'll bypass the power of the rules engine (invoked by the <filter> element) and the <outage-calendar> functionality, despite their coolness and power.

At this point, you should have your bearings enough to get a rudimentary configuration in place and to let discovery, capsd, and the polling subsystem do their thing for you. The next part is simple: View the results.

Assuming you've gotten everything installed already, you can start up OpenNMS with:

/opt/OpenNMS/bin/ start

And once it returns for you, you can point a browser at:


(username: admin, password: admin)

You should find things beginning to populate in 5-10 minutes. This includes seeing nodes starting to be populated into categories on the main panel, events being displayed in the events browser, and perhaps even outages appearing in the "Nodes with Outages" table.

Yes, there is a degree of voodoo involved in getting the user interface configured for your environment, and we haven't even talked about SNMP yet, but the good news is that there's time for that later. In the interim, you will be able to start basic monitoring of your environment for service availability. And you can rest easy knowing that OpenNMS ships with sensible defaults and a lot of preconfiguration, so many of the things you haven't yet gotten around to, you may never need to.

Shane O'Donnell serves as OpenNMS project manager and chief architect, drawing on extensive experience in the network management industry. He holds an M.S. in something vaguely relevant like Computer Science or something.

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