Linux System Administration Recipes A Problem-Solution Approach

C H A P T E R 3■ ■ ■Monitoring and UpdatingAs mentioned in the previous chapter, centralization will make your life easier. This also extends tocentralizing your system/network monitoring and centralizing as much as possible of the setup and latermanagement of individual machines. Various tools are available to help you do this; this chapter looks atNagios for monitoring, Puppet for centralized configuration management, and another useful tool,ClusterSSH, for repeating commands across your network simultaneously. All three tools are great waysto save yourself some time and effort!3-1. Nagios: Setting Up Centralized MonitoringIt’s embarrassing when the first time you hear about a problem with one of your servers or a desktopmachine is when someone comes to you to complain about it. Far better is to set up some kind ofmonitoring, and Nagios is an excellent tool for this. The setup can be a little complicated, but onceNagios is up and running, it gives you a web-based interface providing oversight of all your machinesand a fair amount of control and information, and it’s very low maintenance.Nagios is centralized: you set up a server, which then collects and displays information on anyclient machines that you tell it to monitor. You can get basic service accessibility information on themonitored machines (whether they’re pingable, whether SSH is OK, whether HTTP/LDAP/NFS is OK,and so on) without needing to install any software on them; the Nagios server does all the work.With a little more setup, you can get more information than this from the monitored machine (CPUinformation, for example), as described in recipe 3-7. The server can react to alert situations (with alertthresholds set by you) by sending e-mail or text to inform a human or by running any script you provide.■ Note For lots more information on Nagios and how to set it up, check out Pro Nagios 2.0 by James Turnbull(Apress, 2006). This book refers to Nagios 2 rather than Nagios 3, but largely the information will carry over.63Download at WoweBook.Com