Zenoss and the Art of Network Monitoring
If a tree falls in the woods and no one is there to hear it, does it make a sound? This the classic query designed to place your mind into the Zen-like state known as the silent mind. Whether or not you want to hear a tree fall, if you run a network, you probably want to hear a server when it goes down. Many organizations utilize the long-established Simple Network Management Protocol (SNMP) as a way to monitor their networks proactively and listen for things going down.
At a rudimentary level, SNMP requires only two items to work: a management server and a managed device (or devices). The management server pulls status and health information at regular intervals from the managed devices and stores the information in a table. Managed devices use local SNMP agents to notify the management server when defined behavior occurs (such as errors or “traps”), which are stored in the same table on the server. The result is an accurate, real-time reporting mechanism for outages. However, SNMP as a protocol does not stipulate how the data in these tables is to be presented and managed for the end user. That's where a promising new open-source network-monitoring software called Zenoss (pronounced Zeen-ohss) comes in.
Available for most Linux distributions, Zenoss builds on the basic operation of SNMP and uses a comprehensive interface to manage even the largest and most diverse environment. The Core version of Zenoss used in this article is freely available under the GPLv2. An Enterprise version also is available with additional features and support. In this article, we install Zenoss on a CentOS 5.1 system to observe its usefulness in a network-monitoring role. From there, we create a simulated multisystem server network using the following systems: a Fedora-based Postfix e-mail server, an Ubuntu server running Apache and a Windows server running File and Print services. To conserve space, only the CentOS installation is discussed in detail here. For the managed systems, only SNMP installation and configuration are covered.
Begin by selecting your hardware. Zenoss lacks specific hardware requirements, but it relies heavily MySQL, so you can use MySQL requirements as a rough guideline. I recommend using the fastest processor available, 1GB of memory, fast enough hard disks to provide acceptable MySQL performance and Gigabit Ethernet for the network. I ran several test configurations, and this configuration seemed adequate enough for a medium-size network (100+ nodes/devices). To keep configuration simple, all firewalls and SELinux instances were disabled in the test environment. If you use firewalls in your environment, open ports 161 (SNMP), 8080 (Zenoss Management Page) and 514 (if you integrate syslog with Zenoss).
Install CentOS 5.1 on the server using your own preferences. I used a bare install with no X Window System or desktop manager. Assign a static IP address and any other pertinent network information (DNS servers and so forth). After the OS install is complete, install the following packages using the yum command below:
yum install mysql mysql-server net-snmp net-snmp-utils gmp httpd
If the mysqld or the httpd service has not started after yum installs it, start it and set it to run for your configured runlevel. Next, download the latest Zenoss Core .rpm from Sourceforge.net (2.1.3 at the time of this writing), and install it using rpm from the command line. To start all the Zenoss-related dæmons after the .rpm has been installed, type the following at a command prompt:
service zenoss start
Launch a Web browser from any machine, and type the IP address of the Zenoss server using port 8080 (for example, http://192.168.142.6:8080). Log in to the site using the default account admin with a password of zenoss. This brings up the main dashboard. The dashboard is a compartmentalized view of the state of your managed devices. If you don't like the default display, you can arrange your dashboard any way you want using the various drop-down lists on the portlets (windows). I recommend setting the Production States portlet to display Production, so we can see our test systems after they are added.
Almost everything related to managed devices in Zenoss revolves around classes. With classes, you can create an infinite number of systems, processes or service classifications to monitor. To begin adding devices, we need to set our SNMP community strings at the top-level /Devices class. SNMP community strings are like passphrases used to authenticate traffic between devices. If one device wants to communicate with another, they must have matching community names/strings. In many deployments, administrators use the default community name of public (and/or private), which creates a security risk. I recommend changing these strings and making them into a short phrase. You can add numbers and characters to make the community name more complex to guess/crack, but I find phrases easier to remember.
Click on the Devices link on the navigation menu on the left, so that /Devices is listed near the top of the page. Click on the zProperties tab and scroll down. Enter an SNMP community string in the zSNMPCommunitiy field. For our test environment, I used the string whatsourclearanceclarence. You can use different strings with different subclasses of systems or individual systems, but by setting it at the /Devices class, it will be used for any subclasses unless it is overridden. You also could list multiple strings in the zSNMPCommunities under the /Devices class, which allows you to define multiple strings for the discovery process discussed later. Make sure your community string (zSNMPCommunity) is in this list.
|Contrast Security's Contrast Enterprise||Aug 30, 2016|
|illusive networks' Deceptions Everywhere||Aug 29, 2016|
|Happy Birthday Linux||Aug 25, 2016|
|ContainerCon Vendors Offer Flexible Solutions for Managing All Your New Micro-VMs||Aug 24, 2016|
|Updates from LinuxCon and ContainerCon, Toronto, August 2016||Aug 23, 2016|
|NVMe over Fabrics Support Coming to the Linux 4.8 Kernel||Aug 22, 2016|
- Download "Linux Management with Red Hat Satellite: Measuring Business Impact and ROI"
- Contrast Security's Contrast Enterprise
- illusive networks' Deceptions Everywhere
- Happy Birthday Linux
- What I Wish I’d Known When I Was an Embedded Linux Newbie
- New Version of GParted
- All about printf
- ContainerCon Vendors Offer Flexible Solutions for Managing All Your New Micro-VMs
- Tech Tip: Really Simple HTTP Server with Python
With all the industry talk about the benefits of Linux on Power and all the performance advantages offered by its open architecture, you may be considering a move in that direction. If you are thinking about analytics, big data and cloud computing, you would be right to evaluate Power. The idea of using commodity x86 hardware and replacing it every three years is an outdated cost model. It doesn’t consider the total cost of ownership, and it doesn’t consider the advantage of real processing power, high-availability and multithreading like a demon.
This ebook takes a look at some of the practical applications of the Linux on Power platform and ways you might bring all the performance power of this open architecture to bear for your organization. There are no smoke and mirrors here—just hard, cold, empirical evidence provided by independent sources. I also consider some innovative ways Linux on Power will be used in the future.Get the Guide