7 free tools every network needs

From device discovery to visibility into systems, networks, and traffic flows, these free open source monitoring tools have you covered

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Observium is a network and host monitor that can scan ranges of addresses for systems to monitor using common SNMP credentials. Packaged as a LAMP application, Observium is relatively easy to set up and configure, requiring the usual installations of Apache, PHP, and MySQL, database creation, Apache configuration, and the like. It is designed to be installed as its own server with a dedicated URL, rather than under a larger Web tree.

From there, you can log into the GUI and start adding hosts and networks, as well as autodiscovery ranges and SNMP data to have Observium crawl around the network and gather data on each system discovered. Observium can also discover network devices via CDP, LLDP, or FDP, and host agents can be deployed to Linux systems to aid in data collection.


Observium combines system and network monitoring with performance trending. It can be configured to track almost any available metric. 

All of this data is presented in an easily navigated user interface that provides a multitude of statistics, charts, and graphs. This includes everything from ping and SNMP response times to graphs of IP throughput, fragmentation, packet counts, and so forth. Depending on the device, this data will be available for every port discovered and include an inventory of modular devices.

For servers, Observium will display CPU, RAM, storage, swap, temperature, and event log status. You can incorporate data collection and performance graphing on services as well, including Apache, MySQL, BIND, Memcached, Postfix, and others.

Observium plays nice as a VM, so can quickly become a go-to tool for server and network status information. It's a great way to bring autodiscovery and charting to a network of any size.


Too often, IT administrators think they can't color outside the lines. Whether we're dealing with a custom application or an "unsupported" piece of hardware, many of us believe that if a monitoring tool can't handle it immediately, it can't be handled. That's simply not the case, and with a little bit of elbow grease, almost anything can be monitored, cataloged, and made more visible.

An example might be a custom application with a database back end, like a Web store or an internal finance application. Management wants to see pretty graphs and charts depicting usage data in some form or another. If you're using, say, Cacti already, you have several ways to bring this data into the fold, such as constructing a simple Perl or PHP script to run queries on the database and pass counts back to Cacti or even an SNMP call to the database server using private MIBs (management information bases). It can be done, and it can generally be done easily.

If it's unsupported hardware, as long as it speaks SNMP, you can most likely get at the data you need, though it may take a little research. Once you have the right MIBs to query, you can then use that information to write or adapt plug-ins to collect that data. In many cases, you can even integrate your cloud services into this monitoring by using standard SNMP on those instances, or by using an API provided by your cloud vendor. Just because you have cloud services doesn’t mean you should trust all your monitoring to your cloud provider. The provider doesn’t know your application and service stack as well as you do.

Getting most of these tools running usually isn't much of a challenge. They typically have packages available to download for most popular Linux distributions, if they aren't already in the package list. In some cases, they may come preconfigured as a virtual server. Configuring and tweaking the tools can take quite a while depending on the size of the infrastructure, but getting them going initially is usually a cinch. At the very least, they’re worth a test-drive.

No matter which of these tools you use to keep tabs on your infrastructure, it will essentially provide the equivalent of at least one more IT admin -- one that can't necessarily fix anything, but one that watches everything, 24/7/365. The up-front time investment is well worth the effort, no matter which way you cut it. Be sure to run a small set of autonomous monitoring tools on another server, watching the main monitoring server. This is a case where it's always best to ensure the watcher is being watched.

This story, "7 free tools every network needs" was originally published by InfoWorld.

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