Killer open source monitoring tools Page 1 of 6 Published on InfoWorld (http://www.infoworld.com) Home > Test Center > Networking > Killer open source monitoring tools > Killer open source monitoring tools Killer open source monitoring tools By Paul Venezia Created 2008-11-24 04:00AM In the real estate world, the mantra is location, location, location. In the network and server administration world, the mantra is visibility, visibility, visibility. If you don't know what your network and servers are doing at every second of the day, you're flying blind. Sooner or later, you're going to meet with disaster. Fortunately, there are a plethora of good tools, both commercial and open source that can shine much- needed light into your environment. Because good and free always beats good and costly, I've compiled a list of my favorite open source tools that prove their worth day in and day out in networks of any size. From network and server monitoring to trending, graphing, and even switch and router configuration backups, these utilities will see you through. [ Need a Linux that can boot from a pen drive, run in a sliver of RAM, rejuvenate an old system, or rescue data from a dead PC? See "Specialty Linuxes to the rescue [1]." Read about the very best open source software products in InfoWorld's Best of Open Source Software Awards 2008 [2]. ] Cacti (www.cacti.net [3]) First, there was MRTG. Back in the heady days of the 1990s, Tobi Oetiker saw fit to write a simple graphing tool built on a round-robin database scheme that was perfectly suited to displaying router throughput. MRTG begat RRDTool, which is the self- contained round-robin database and graphing solution in use in a staggering number of open source tools today. Cacti is the current standard-bearer of open source network graphing, and takes the original goals of MRTG to whole new levels. Cacti is a LAMP/WAMP (Linux/Windows, Apache, MySQL, and Perl/PHP/Python) application that provides a complete graphing framework for data of nearly every sort. In some of my more advanced installations of Cacti, I'm collecting data on everything from fluid return temperatures in datacenter cooling units to free space on filer volumes to FLEXlm license utilization. If a device or service returns numeric data, it can probably be integrated into Cacti. There are templates to monitor a wide variety of devices, from Linux and Windows servers to Cisco routers and switches -- basically anything that speaks SNMP. There are also collections of contributed templates for an file:///C:/Users/mishra/Desktop/Corporate%20WAN%20Monitor/39860.htm 19/06/2012 Killer open source monitoring tools Page 2 of 6 even greater array of hardware and software. I've written several data templates for Cacti that can be downloaded from the project site, including the FLEXlm monitoring code [4]. Cacti's default collection method is SNMP, but local Perl or PHP scripts can be used as well. The framework deftly separates data collection and graphing into discrete instances, so it's easy to rework and reorganize existing data into different displays. Not only that, but you can easily select specific timeframes and sections of graphs just by clicking and dragging. In some of my installations, I have data going back several years, which proves invaluable when determining if current behavior of a network device or server is truly anomalous or, in fact, occurs with some regularity. Using the PHP Network Weathermap [5] plug-in for Cacti, you can easily create live network maps showing link utilization between network devices, complete with graphs that appear when you hover over a depiction of a network link. In many places where I've implemented Cacti, these maps wind up running 24x7 on 42-inch LCD monitors mounted high on the wall, providing the whole IT staff with at-a-glance updates on network utilization and link status. Cacti is extremely well written, well presented, and infinitely customizable. There really is no comparison to this tool in either the open source or commercial world. Nagios (www.nagios.org [6]) Nagios is a surprisingly mature network monitoring framework that's been in active development for many years. Written in C, it's just about everything that system and network administrators could ask for in a monitoring package. The Web GUI is fast and intuitive (although it's even better with the contributed Nuvola style), and the back end is extremely robust. As with Cacti, there is a very active community supporting Nagios, and plug-ins exist for a massive array of hardware and software. From basic ping tests to integration with plug-ins like WebInject, you can constantly monitor the status of servers, services, network links, and basically anything that speaks IP. I use Nagios to monitor server disk space, RAM and CPU utilization, FLEXlm license utilization, server exhaust temperatures, and WAN and Internet link latency. I even use it to ensure that Web servers are not only answering http queries, but that they're returning the expected pages and haven't been hijacked. Network and server monitoring is obviously incomplete without notifications. Nagios has a full e-mail/SMS notification engine, and an escalation layout that can be used to make intelligent decisions on who and when to notify, which can save plenty of sleep if used correctly. In addition, I’ve integrated Nagios notifications with Jabber, so the instant an exception is thrown I get an IM from Nagios detailing the problem. The Web GUI can be used to quickly suspend notifications or acknowledge problems when they occur, and can even record notes entered by admins. As if this wasn't enough, a mapping function displays all the monitored devices in a logical representation of their placement on the network, with color-coding to show problems as they occur. The downside to Nagios is the configuration. The config is best done via command line and can present a significant learning curve. As with many tools, the capabilities of file:///C:/Users/mishra/Desktop/Corporate%20WAN%20Monitor/39860.htm 19/06/2012 Killer open source monitoring tools Page 3 of 6 Nagios are immense, but the effort to take advantage of some of those capabilities is equally significant. ' But don't let the complexity discourage you -- Nagios has saved my bacon more times than I can possibly recall. The early-warning systems provided by this tool for so many different aspects of the network cannot be overstated. It's easily worth the time investment. I've written several Nagios plug-ins, including one that monitors a wide variety of APC hardware [7], and they've paid me back many times over. NeDi (www.nedi.ch [8]) If you've ever had to search for a device on your network by telnetting into switches and doing MAC address lookups, or you just wish that you could tell where a certain device is physically located (or, perhaps more important, where it was located), then you should take a good look at NeDi. NeDi is a LAMP application that regularly walks the MAC address and ARP tables on your network switches, cataloging every device it discovers in a local database. You can then log into the NeDi Web GUI and conduct searches to determine the switch and switch port of any device by MAC address, IP address, or DNS name. In addition, NeDi collects as much information as possible from every network device it encounters, pulling serial numbers, firmware and software versions, current temps, module configurations, and so forth. You can even use NeDi to flag MAC addresses of devices that are missing or stolen, and NeDi will watch to see if they appear on the network again. Configuration is straightforward, with a single config file that allows for a significant amount of customization, including the ability to skip devices based on regular expressions or network-border definitions. You can even include seed lists of devices to query if the network is separated by nondiscoverable boundaries, as in the case of an MPLS network. NeDi usually uses Cisco Discovery Protocol or Link Layer Discovery Protocol, discovering new switches and routers as it rolls through the network, then connecting to them to collect their information. Once the initial configuration has been set, running a discovery is fairly quick, and runs from cron at set intervals. NeDi also integrates with Cacti to some degree, and if provided with the credentials to a functional Cacti installation, device discoveries will link to the associated Cacti graphs for that device. Ntop (www.ntop.org [9]) Ntop is the product of a fantastically focused mind -- that of Luca Deri, the project's author. Ntop is a top-notch network traffic monitor married to a fast and simple Web GUI. It's written in C and completely self-contained; you run a single process configured to watch a specific network interface, and that's about all there is to it. Ntop provides easily digestible graphs and tables showing current and past network traffic, including protocol, source, destination, and history of specific transactions as well as the hosts on either end. Ntop leverages the aforementioned RRDTool to provide an impressive array of network utilization graphs, including trends, and incorporates a plug-in framework for an array of add-ons, such as NetFlow and sFlow monitors. file:///C:/Users/mishra/Desktop/Corporate%20WAN%20Monitor/39860.htm 19/06/2012 Killer open source monitoring tools Page 4 of 6 Ntop even has an RPC framework that can be used to provide native data arrays to a wide variety of languages.