Install NSCA

1 原理图
NSCA

NSCA is an addon that allows you to send passive check results from remote Linux/Unix hosts to the Nagios Core daemon running on
the monitoring server. This is very useful in distributed and redundant/failover monitoring setups.
The NSCA addon can be found on Nagios Exchange.

2 安装
2.1 安装nagios
参考 安装nagios 4.4

2.2 安装nsca
2.2.1 下载nsca
nsca-2.9.1.tar.gz
2.2.1 安装server端nsca
2.2.1.1 解压、安装
tar -xzvf ./nsca-2.9.1.tar.gz
cd ./nsca-2.9.1
./configure
make all
1) 会在src目录下生成两个程序 nsca send_nsca（主程序）
2) sample-config中会有nsca.cfg与send_nsca.cfg（配置文件）
3) 当前目录下会有一个init-script（启动脚本）

复制主程序

cp src/nsca /usr/local/nagios/bin/

复制主配置文件

cp sample-config/nsca.cfg /usr/local/nagios/etc

修改属组属主

chown nagios.nagios /usr/local/nagios/bin/nsca
chown nagios.nagios /usr/local/nagios/etc/nsca.cfg

配置服务

cp init-script /etc/init.d/nsca
chmod a+x /etc/init.d/nsca

修改nsca配置文件

vi /usr/local/nagios/etc/nsca.cfg
aggregate_writes=1
max_packet_age=60
password=nsca0622
#此处和分布式监控服务器密码一致

修改nagios配置文件

vi /usr/local/nagios/etc/nagios.cfg
check_external_commands=1

配置nagios检查扩展命令

accept_passive_service_checks=1

配置接受被动服务检测的结果

accept_passive_host_checks=1
#配置接受被动主机检测的结果
#
service_freshness_check_interval=600
host_freshness_check_interval=600

在分布式中心服务器需要配置启用外部事件处理、启用被动检测、自动转换主机状态为软状态。以避免出现主机状态频繁切换造成的虚假报警。下面是Nagios配置文件中被动检测相关配置节选部分。

passive_host_checks_are_soft=1

关闭主动监测

execute_host_checks=0
execute_service_checks=0
enable_flap_detection=0

验证配置文件是否正确

/usr/local/nagios/bin/nagios -v /usr/local/nagios/etc/nagios.cfg
Things look okay – No serious problems were detected during the pre-flight check

启动nagios和nsca服务

systemctl restart nagios.service
systemctl restart nsca.service

systemctl enable nagios.service
systemctl enable nsca.service

2.2.1.2 配置host service command

host

vi /usr/local/nagios/etc/objects/templates.cfg

This is NOT a real host, just a template!

define host {

name generic-host ; The name of this host template
notifications_enabled 1 ; Host notifications are enabled
event_handler_enabled 1 ; Host event handler is enabled
flap_detection_enabled 1 ; Flap detection is enabled
process_perf_data 1 ; Process performance data
retain_status_information 1 ; Retain status information across program restarts
retain_nonstatus_information 1 ; Retain non-status information across program restarts
notification_period 24×7 ; Send host notifications at any time
register 0 ; DON'T REGISTER THIS DEFINITION – ITS NOT A REAL HOST, JUST A TEMPLATE!
action_url /pnp4nagios/index.php/graph?host=$HOSTNAME$&srv=HOST
check_freshness 1
freshness_threshold 600
passive_checks_enabled 1
active_checks_enabled 0
check_command check_dummy!0
}

service

This is NOT a real service, just a template!

define service {

name generic-service ; The 'name' of this service template
active_checks_enabled 1 ; Active service checks are enabled
passive_checks_enabled 1 ; Passive service checks are enabled/accepted
parallelize_check 1 ; Active service checks should be parallelized (disabling this can lead to major performance problems)
obsess_over_service 1 ; We should obsess over this service (if necessary)
check_freshness 0 ; Default is to NOT check service 'freshness'
notifications_enabled 1 ; Service notifications are enabled
event_handler_enabled 1 ; Service event handler is enabled
flap_detection_enabled 1 ; Flap detection is enabled
process_perf_data 1 ; Process performance data
retain_status_information 1 ; Retain status information across program restarts
retain_nonstatus_information 1 ; Retain non-status information across program restarts
is_volatile 0 ; The service is not volatile
check_period 24×7 ; The service can be checked at any time of the day
max_check_attempts 3 ; Re-check the service up to 3 times in order to determine its final (hard) state
check_interval 10 ; Check the service every 10 minutes under normal conditions
retry_interval 2 ; Re-check the service every two minutes until a hard state can be determined
contact_groups admins ; Notifications get sent out to everyone in the 'admins' group
notification_options w,u,c,r ; Send notifications about warning, unknown, critical, and recovery events
notification_interval 60 ; Re-notify about service problems every hour
notification_period 24×7 ; Notifications can be sent out at any time
register 0 ; DON'T REGISTER THIS DEFINITION – ITS NOT A REAL SERVICE, JUST A TEMPLATE!
action_url /pnp4nagios/index.php/graph?host=$HOSTNAME$&srv=$SERVICEDESC$
check_command check_dummy!0
check_freshness 1
freshness_threshold 600
active_checks_enabled 0
}

command

vi /usr/local/nagios/etc/objects/commands.cfg

define command{
command_name service-is-stale
command_line $USER1$/staleservice.sh
}
define command{
command_name check_dummy
command_line $USER1$/check_dummy $ARG1$
}

配置staleservice.sh 脚本

vi /usr/local/nagios/libexec/staleservice.sh

#!/bin/sh
/bin/echo "CRITICAL: Service results are stale!"
exit 2

chmod a+x /usr/local/nagios/libexec/staleservice.sh
chown nagios:nagios /usr/local/nagios/libexec/staleservice.sh

2.2.2 安装client端nsca（分布式服务器）
2.2.2.1 编译
编译同server方法一样
tar -xzvf ./nsca-2.9.1.tar.gz
cd ./nsca-2.9.1
./configure
make all
1）会在src目录下生成两个程序 nsca send_nsca（主程序）
2）sample-config中会有nsca.cfg与send_nsca.cfg（配置文件）

复制命令

cp src/send_nsca /usr/local/nagios/bin/

复制配置文件

cp sample-config/send_nsca.cfg /usr/local/nagios/etc/

修改属组属主

chown nagios.nagios /usr/local/nagios/bin/send_nsca
chown nagios.nagios /usr/local/nagios/etc/send_nsca.cfg

2.2.2.2 修改配置信息

修改配置 /usr/local/nagios/etc/send_nsca.cfg

vi /usr/local/nagios/etc/send_nsca.cfg

password=nsca0622 #此处和中心服务器密码一致

在分布式服务器的对象配置文件里只定义那些由它直接监控的主机与服务的对象(与中心服务器定义监控主机和服务对象一致)；

修改nagios配置文件

vi /usr/local/nagios/etc/nagios.cfg

enable_notifications=0 # 阻止它直接送出任何通知信息
obsess_over_services=1 # 配置为强迫型服务(obsess over services)类型
ocsp_command=submit_service_check_result #定义一个强迫型服务处理(ocsp)命令
obsess_over_hosts=1 # 配置为强迫型主机(obsess over hosts)类型
ochp_command=submit_host_check_result #定义一个强迫型主机处理(ochp)命令

定义command

vi /usr/local/nagios/etc/objects/commands.cfg

submit_service_check_result

define command{
command_name submit_service_check_result
command_line /usr/local/nagios/libexec/eventhandlers/submit_service_check_result $HOSTNAME$ '$SERVICEDESC$' $SERVICESTATE$ '$SERVICEOUTPUT$ |$SERVICEPERFDATA$'
}

submit_host_check_result

define command{
command_name submit_host_check_result
command_line /usr/local/nagios/libexec/eventhandlers/submit_host_result $HOSTNAME$ $HOSTSTATE$ '$HOSTOUTPUT$ |$HOSTPERFDATA$'
}

编辑

submit_host_check_result

submit_service_check_result

su – nagios
mkdir /usr/local/nagios/libexec/eventhandlers
cd /usr/local/nagios/libexec/eventhandlers
vi ./submit_service_check_result

#!/bin/sh

Arguments:

$1 = host_name (Short name of host that the service is

associated with)

$2 = svc_description (Description of the service)

$3 = state_string (A string representing the status of

the given service – "OK", "WARNING", "CRITICAL"

or "UNKNOWN")

$4 = plugin_output (A text string that should be used

as the plugin output for the service checks)

Convert the state string to the corresponding return code

PATH="/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin"
export PATH
PROGNAME=$(basename "$0")
PROGPATH=$(echo "$0" | sed -e 's,[\/][^\/][^\/]*$,,')
REVISION="2.2.1"
PATH="/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin"

. "$PROGPATH"/../utils.sh

central_server=9.1.9.90
return_code=-1
#echo "1:"$1 >>/tmp/nsca_c.log
#echo "2:"$2 >>/tmp/nsca_c.log
#echo "3:"$3 >>/tmp/nsca_c.log
#echo "4:"$4 >>/tmp/nsca_c.log
case "$3" in
OK)
return_code=$STATE_OK
;;
WARNING)
return_code=$STATE_WARNING
;;
CRITICAL)
return_code=$STATE_CRITICAL
;;
UNKNOWN)
return_code=$STATE_UNKNOWN
;;
esac

pipe the service check info into the send_nsca program, which

in turn transmits the data to the nsca daemon on the central

monitoring server

/usr/bin/printf "%s\t%s\t%s\t%s\n" "$1" "$2" "$return_code" "$4" | /usr/local/nagios/bin/send_nsca -H $central_server -c /usr/local/nagios/etc/send_nsca.cfg
/usr/bin/printf "%s\t%s\t%s\t%s\n" "$1" "$2" "$return_code" "$4" >>/tmp/nsca_c.log

chmod a+x ./submit_service_check_result

vi ./submit_host_result

#!/bin/sh

Arguments:

= host_name (Short name of host that the service is

associated with)

= svc_description (Description of the service)

= state_string (A string representing the status of

the given service – "OK", "WARNING", "CRITICAL"

or "UNKNOWN")

= plugin_output (A text string that should be used

as the plugin output for the service checks)

#

Convert the state string to the corresponding return code

central_server=9.1.9.90

return_code=-1
case "$2" in
UP)
return_code=0
;;

DOWN)
return_code=1
;;

UNREACHABLE)
return_code=2
;;
esac

pipe the service check info into the send_nsca program, which

in turn transmits the data to the nsca daemon on the central

monitoring server

/usr/bin/printf "%s\t%s\t%s\n" "$1" "$return_code" "$3" | /usr/local/nagios/bin/send_nsca -H $central_server -c /usr/local/nagios/etc/send_nsca.cfg
/usr/bin/printf "%s\t%s\t%s\n" "$1" "$return_code" "$3" >>/tmp/nsca_c_h.log

chmod a+x ./submit_host_result

检查nagios配置，并重启

/usr/local/nagios/bin/nagios -v /usr/local/nagios/etc/nagios.cfg
systemctl restart nagios.service

systemctl enable nagios.service

注意点：

1、中心服务器和分布式服务器的时间一定要调整一致
2、分布式服务器监控客户端主机可以用任何方式，主动被动都可以
3、分布式上定义的监控主机与服务，在中心服务器上也要定义，保证主机名（host_name）和服务描述（service_description）一致。
4、分布式服务器上定义的服务检测命令（check_command）是真正的检测服务的命令 ，中心服务器上定义的服务检测命令（check_command）是当中心服务器由被动检测变为主动检测时执行的命令（也就是当分布式主机不发送检测命令时中心服务器执行的命令），正常情况下不执行这个命令。