搭建nagios的目的就是为了他的报警系统，nagios据我所了解可以有三种报警：
　　一、声音报警
　　二、电子邮件报警
　　三、手机短讯报警
　　下面是我的邮件报警的配置过程：
　　1、开启系统自带的sendmail邮件系统
　　service sendmail start
　　如果没有安装，可以yum一下
　　yum install -y sendmail*
　　service sendmail restart
　　测试发送邮件：
　　echo "test" | mail [email protected]
　　我系统在关掉iptables和selinux前提下是正常的
　　2、配置nagios中报警邮箱
　　vi /usr/local/nagios/etc/objects/contacts.cfg
　　define contact{
　　contact_name                    nagiosadmin             ; Short name of user
　　use                             generic-contact         ; Inherit default values from generic-contact template (defined above)
　　alias                           Nagios Admin            ; Full name of user
　　email                           [email protected]   ; <<***** CHANGE THIS TO YOUR EMAIL ADDRESS ******
　　}
　　在email那里加上自己的邮箱，如果有多个可以用逗号隔开
　　3、设置报警方式：
　　vi /usr/local/nagios/etc/objects/templates.cfg
　　define contact{
　　name                            generic-contact         ; The name of this contact template
　　service_notification_period     24x7                    ; service notifications can be sent anytime
　　host_notification_period        24x7                    ; host notifications can be sent anytime
　　service_notification_options    w,u,c,r,f,s             ; send notifications for all service states, flapping events, and scheduled downtime events
　 　host_notification_options       d,u,r,f,s               ; send notifications for all host states, flapping events, and scheduled downtime events
　　service_notification_commands   notify-service-by-email ; send service notifications via email
　　host_notification_commands      notify-host-by-email    ; send host notifications via email
　　register                        0                       ; DONT REGISTER THIS DEFINITION - ITS NOT A REAL CONTACT, JUST A TEMPLATE!
　　}
　　这两个notify-service-by-email 和  notify-host-by-email    是在command.cfg那里定义的，看看是怎么定义的：
　　# 'notify-host-by-email' command definition
　　define command{
　　command_name    notify-host-by-email
　 　command_line    /usr/bin/printf "%b" "***** Nagios ***** Notification Type: $NOTIFICATIONTYPE$ Host: $HOSTNAME$ State: $HOSTSTATE$ Address: $HOSTADDRESS$ Info: $HOSTOUTPUT$ Date/Time: $LONGDATETIME$ " | /bin/mail -s "** $NOTIFICATIONTYPE$ Host Alert: $HOSTNAME$ is $HOSTSTATE$ **" $CONTACTEMAIL$
　　}
　　# 'notify-service-by-email' command definition
　　define command{
　　command_name    notify-service-by-email
　 　command_line    /usr/bin/printf "%b" "***** Nagios ***** Notification Type: $NOTIFICATIONTYPE$ Service: $SERVICEDESC$ Host: $HOSTALIAS$ Address: $HOSTADDRESS$ State: $SERVICESTATE$ Date/Time: $LONGDATETIME$ Additional Info: $SERVICEOUTPUT$ " | /bin/mail -s "** $NOTIFICATIONTYPE$ Service Alert: $HOSTALIAS$/$SERVICEDESC$ is $SERVICESTATE$ **" $CONTACTEMAIL$
　　}
　　这里已经默认配置好，我们不用修改直接调用就是了
　　最后重启服务：
　　service nagios retart
　　然后随便关掉一些服务测试一下效果！