Monit是一个Linux/UNIX系统上开源的进程、文件、目录和文件系统监控和管理工具。官网：http://mmonit.com/。这里系统为CentOS6.2，监控机IP为192.168.1.100，被监控机IP为192.168.1.200。

一、被监控机安装monit
1、安装monit
monit有源码和编译好的二进制版，目前最新为monit-5.3.2，这里使用pre-compiled binaries版，省时省力。

选择相应的系统下载：

cd /tmp
wget http://mmonit.com/monit/dist/binary/5.3.2/monit-5.3.2-linux-x86.tar.gz
tar -axvf monit-5.3.2-linux-x86.tar.gz

2、将monit放到合适的位置：

mv monit-5.3.2 /usr/local/monit

3、复制配置文件

cp /usr/local/monit/conf/monitrc /etc

4、简单编辑配置文件

vim /etc/monitrc

设置每2分钟监控一次。
找到：

set daemon 60

修改：

set daemon 120

找到：

set httpd port 2812 and
    use address localhost  # only accept connection from localhost
    allow localhost        # allow localhost to connect to the server and
    allow admin:monit      # require user 'admin' with password 'monit'
    allow @monit           # allow users of group 'monit' to connect (rw)
    allow @users readonly  # allow users of group 'users' to connect readonly

可以看到默认是只允许本机登陆。不过我们可以通过另一台机器上的M/Monit来监控它。修改为：

set eventqueue basedir /var/monit/ slots 1000
set mmonit http://monit:monit@192.168.1.100:8080/collector
set httpd port 2812 and
    use address 192.168.1.200
    allow localhost
    allow admin:monit
    allow 192.168.1.100

找到：

include /etc/monit.d/*

将前面的#去掉。

5、在/etc/monit.d目录内添加监控脚本
建立该目录：

mkdir /etc/monit.d

这里以监控httpd、sshd服务为例：
监控脚本内容可参考monitrc自带的内容。

监控sshd服务：

vim /etc/monit.d/sshd

输入：

check process sshd with pidfile /var/run/sshd.pid
   start program  "/etc/init.d/sshd start"
   stop program  "/etc/init.d/sshd stop"
   if failed port 22 protocol ssh then restart
   if 5 restarts within 5 cycles then timeout

监控httpd服务：

vim /etc/monit.d/httpd

输入：

check process apache with pidfile /var/run/httpd/httpd.pid
   group www
   start program = "/etc/init.d/httpd start"
   stop program  = "/etc/init.d/httpd stop"
   if failed host www.example.com port 80 protocol http
      then restart
   if cpu is greater than 80% for 2 cycles then alert
   if cpu > 80% for 5 cycles then restart
   if totalmem > 512 MB for 5 cycles then restart
   if children > 200 then restart
   if loadavg(5min) greater than 10 for 8 cycles then stop
   if 3 restarts within 5 cycles then timeout

6、检查monit语法

/usr/local/monit/bin/monit -t

Control file syntax OK

7、启动monit

/usr/local/monit/bin/monit

二、监控机安装M/Monit
1、安装M/Monit
M/Monit是一个管理monit的web-interface，M/Monit解压后就能运行。目前最新为M/Monit 2.4。

cd /root
wget http://mmonit.com/dist/mmonit-2.4-linux-x86.tar.gz
tar -zxvf mmonit-2.4-linux-x86.tar.gz
mv mmonit-2.4 mmonit

2、运行mmonit

cd /root/mmonit
./bin/mmonit

浏览器访问http://监控机IP:8080，默认用户名、密码：admin swordfish登陆。数据库使用自带的sqlite。

参考资料：
http://linuxjcq.blog.51cto.com/3042600/717843
http://www.vpsee.com/2009/08/monitor-linux-server-using-monit/
http://mmonit.com/monit/documentation/monit.html#init_support