One trend that is on the rise in Linux administration is that administrators are required to do more with less time. Doing more with less is a concept that generates numbers for the bottom line of the business but increases the level of stress for an administrator. One way to ease that load is to set up automatic monitoring of those important servers and services that your company uses. Nagios is an excellent choice for that monitoring requirement.
Nagios supports an administrator in two ways. Nagios will monitor servers, routers, switches, and printers when you are busy doing other important tasks. In addition, Nagios will provide you with peace of mind and that you will be notified if things go wrong.
Nagios 3: Easier Set Up
Nagios 3 provides about 30 new macros, updated documentation and more generic definitions available to reduce your typing. Nagios has had a reputation of being an application that is difficult to set up. While Nagios does offer some challenges for set up, Nagios 3 is easier and faster to set up than version 2. In fact, a working Nagios server is possible after 20 minutes. Nagios provides the ability to monitor important services like HTTP, SMTP, POP3, etc. In addition you can monitor processes, CPU usage, disk space, RAM, etc. on those hosts so that you will see warnings as resource approach dangerous levels.
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The unique feature of Nagios is that it will notify you if your servers develop a problem. You can be notified by email, pager, phone, instant messenger, audio alerts, etc. In other words you can configure Nagios to contact you in any way that is necessary. Notifications occur when a hard state change happens or when a host or service remains in a hard non-OK state for the set notification time period. You can set specific admins or groups who will be notified when these states require notification. You are able to set up time periods when the system is aware of system down times.
Monitor Linux or Windows Machines
Nagios allows you to use NRPE (Nagios Remote Plugin Executor) to monitor either Linux or Windows machines. When you monitor these machines you can monitor services or machine load, users, memory, etc. This provides you with awareness of critcal services that could take a great deal of time to monitor manually.
Monitor Printers, Switches, Routers
Nagios allows you to monitor printer toner levels, check to see if they are jammed, out of paper, etc. You can use simple methods to check switches and routers or more advanced features of monitoring traffic, bandwidth, packet loss and round trip averages.
Nagios does provide some good documentation however you will need to recognize that the paths for config files, plugins, etc. will likely be different for each distribution. As a result one of the first things you should do is become familiar with the paths of all of your program files as soon as possible.
Nagios provides a web interface that shows the status of hosts and services that you are monitoring in a graphical format.
Nagios 3 will easily install on CentOs or Ubuntu servers. Nagios 3 is in the Ubuntu repositories while you will need to add rpmforge to the repositories for CentOS to install with yum. Of course, you can complile Nagios for any Linux distribution.