用 Nagios 监控网络和网络服务器

Nagios可以对服务器进行全面的监控，包括服务（apache、mysql、ntp、dns、disk、qmail和sshd等等）的状态，服务器的状态（up、down等等）。它是一个完全GPL协议的开源软件包，包含有nagios主程序和它的各个插件，配置非常灵活，可以监视的项目很多，可以自定义shell脚本进行监控服务，非常适合大型网络。

Nagios的包含主动监控和被动监控。

主动检查是通过监控中心的主机发出请求，让运行在远程主机上的nrpe守护进程收集信息，然后报告它，它通过web接口把数据显示在页面上。

它的工作原理如下：

被动监控是当远程被监控主机处于防火墙之内的时候，只有远程主机可以访问到监控中心，防火墙之内可以设置另外一个监控中心，远程监控中心的nagios收集服务器信息以后，和nsca报告，由naca客户端报告naca的服务器端，然后报告监控中心的nagios，通过web接口显示监控结果。

nagios的功能非常强大，http://www.nagios.org/是它的窝，只有e文、法文和日文，没有中文，可惜啊。

我现在引用它的一段文字进行总结一下到底什么是nagios：

What Is This?

什么是nagios？

Nagios® is a system and network monitoring application. It watches hosts and services that you specify, alerting you when things go bad and when they get better.

Nagios was originally designed to run under Linux, although it should work under most other unices as well.

Some of the many features of Nagios® include:

Monitoring of network services (SMTP, POP3, HTTP, NNTP, PING, etc.)

Monitoring of host resources (processor load, disk usage, etc.)

Simple plugin design that allows users to easily develop their own service checks

Parallelized service checks

Ability to define network host hierarchy using "parent" hosts, allowing detection of and distinction between hosts that are down and those that are unreachable

Contact notifications when service or host problems occur and get resolved (via email, pager, or user-defined method)

Ability to define event handlers to be run during service or host events for proactive problem resolution

Automatic log file rotation

Support for implementing redundant monitoring hosts

Optional web interface for viewing current network status, notification and problem history, log file, etc.