yum -y install httpd php gcc glibc glibc-common wget perl gd gd-devel unzip zip
Create a nagios user and nagcmd group for allowing the external commands to be executed through the web interface, add the nagios and apache user to be a part of the nagcmd group.
useradd nagios groupadd nagcmd usermod -a -G nagcmd nagios usermod -a -G nagcmd apache
Install Nagios Server Download the latest version of Nagios Core using the terminal.
cd /tmp/ wget https://assets.nagios.com/downloads/nagioscore/releases/nagios-4.4.3.tar.gz tar -zxvf nagios-4.4.3.tar.gz cd /tmp/nagios-4.4.3
Compile and Install Nagios.
./configure --with-nagios-group=nagios --with-command-group=nagcmd make all make install make install-init make install-config make install-commandmode
Install Nagios Web Interface Install the Nagios web configuration using the following command.
make install-webconf
Run the following command to install a Nagios exfoliation theme
make install-exfoliation
Create a user account (nagiosadmin) for logging into the Nagios web interface. Remember the password that you assign to this user – you’ll need it later.
htpasswd -c /usr/local/nagios/etc/htpasswd.users nagiosadmin Restart Apache web server to make the new settings take effect.
systemctl restart httpd systemctl enable httpd
service httpd start chkconfig httpd on
Configure Nagios Server Sample configuration files have now been installed in the /usr/local/nagios/etc directory. These sample files should work fine for getting started with Nagios. You’ll need to make just one change before you proceed.
Edit the /usr/local/nagios/etc/objects/contacts.cfg config file with your favorite editor and change the email address associated with the nagiosadmin contact definition to the address you’d like to use for receiving alerts.
vi /usr/local/nagios/etc/objects/contacts.cfg
Change the Email address field to receive the notification.
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 ******
}
Install Nagios Plugins Download Nagios Plugins to /tmp directory.
cd /tmp wget https://nagios-plugins.org/download/nagios-plugins-2.2.1.tar.gz tar -zxvf nagios-plugins-2.2.1.tar.gz cd /tmp/nagios-plugins-2.2.1/
Compile and install the Nagios plugins.
./configure --with-nagios-user=nagios --with-nagios-group=nagios make make install
Start Nagios Server
Verify the sample Nagios configuration files.
/usr/local/nagios/bin/nagios -v /usr/local/nagios/etc/nagios.cfg
Output:
Nagios Core 4.4.3 Copyright (c) 2009-present Nagios Core Development Team and Community Contributors Copyright (c) 1999-2009 Ethan Galstad Last Modified: 2019-01-15 License: GPL
Website: https://www.nagios.org Reading configuration data... Read main config file okay... Read object config files okay...
Running pre-flight check on configuration data...
Checking objects... Checked 8 services. Checked 1 hosts. Checked 1 host groups. Checked 0 service groups. Checked 1 contacts. Checked 1 contact groups. Checked 24 commands. Checked 5 time periods. Checked 0 host escalations. Checked 0 service escalations. Checking for circular paths... Checked 1 hosts Checked 0 service dependencies Checked 0 host dependencies Checked 5 timeperiods Checking global event handlers... Checking obsessive compulsive processor commands... Checking misc settings...
Total Warnings: 0 Total Errors: 0
Things look okay - No serious problems were detected during the pre-flight check If there are no errors, then start the Nagios service.
service nagios start Start Nagios on system startup.
chkconfig nagios on SELinux See if SELinux is in Enforcing mode.
getenforce Put SELinux in Permissive mode or disable it.
setenforce 0 To make this change permanent, you will have to modify /etc/selinux/config and reboot the system.
Firewall Make sure to allow web server access through the firewall.
firewall-cmd --permanent --add-service=http firewall-cmd --reload
Access Nagios Web Interface Now access the Nagios web interface using the following URL. You’ll be prompted for the username (nagiosadmin) and password you specified earlier.
******NOW CONFIGURE THE CLIENT/REMOTE SERVER
Monitor Remote Linux Systems With Nagios
On Remote Linux System Nagios Remote Plugin Executor (abbreviated as NRPE) plugin allows you to monitor applications and services running on remote Linux / Windows hosts. This NRPE Add-on helps Nagios to monitor local resources like CPU, Memory, Disk, Swap, etc. of the remote host.
Install NRPE Add-on & Nagios Plugins CentOS / RHEL NRPE Server and Nagios plugins are available in the EPEL repository for CentOS / RHEL. So, configure the EPEL repository your CentOS / RHEL system.
rpm -ivh https://dl.fedoraproject.org/pub/epel/epel-release-latest-8.noarch.rpm
rpm -ivh https://dl.fedoraproject.org/pub/epel/epel-release-latest-7.noarch.rpm
rpm -ivh https://dl.fedoraproject.org/pub/epel/epel-release-latest-6.noarch.rpm Use the following command to install NRPE Add-on and Nagios plugins.
yum install -y nrpe nagios-plugins-all
Ubuntu / Debian Use the following command to install NRPE Add-on and Nagios plugins.
sudo apt update
sudo apt install -y nagios-nrpe-server nagios-plugins Configure NRPE Add-on Modify the NRPE configuration file to accept the connection from the Nagios server, Edit the /etc/nagios/nrpe.cfg file.
vim /etc/nagios/nrpe.cfg
sudo nano /etc/nagios/nrpe.cfg Add the Nagios servers IP address, separated by comma like below.
allowed_hosts=192.168.0.10
Configure Nagios Checks The /etc/nagios/nrpe.cfg file contains the basic commands to check the attributes (CPU, Memory, Disk, etc.architecure) and services (HTTP, FTP, etc.) on remote hosts.
The path to Nagios plugins may change depends on your operating system architecture (i386 or x86_64). CentOS / RHEL vim /etc/nagios/nrpe.cfg
Below command lines let you monitor logged in users, system load, root filesystem usage, swap usage and the total number of the process with the help of Nagios plugins.
... ...
command[check_users]=/usr/lib64/nagios/plugins/check_users -w 5 -c 10 command[check_load]=/usr/lib64/nagios/plugins/check_load -w 15,10,5 -c 30,25,20 command[check_root]=/usr/lib64/nagios/plugins/check_disk -w 20% -c 10% -p / command[check_swap]=/usr/lib64/nagios/plugins/check_swap -w 20% -c 10% command[check_total_procs]=/usr/lib64/nagios/plugins/check_procs -w 150 -c 200
command[check_users]=/usr/lib64/nagios/plugins/check_users -w 5 -c 10 command[check_disk_all]=/usr/lib64/nagios/plugins/check_disk -w 20% -c 10% -W 10% -K 5% -N xfs -N ext4 -N nfs command[check_load]=/usr/lib64/nagios/plugins/check_load -w 15,10,5 -c 30,25,20 command[check_all_memory]=/usr/lib64/nagios/plugins/check_mem -w 90 -c 95 command[check_root]=/usr/lib64/nagios/plugins/check_disk -w 20% -c 10% -p /dev/mapper/centos-root command[check_dnslookup_johnlord.comm]=/usr/lib64/nagios/plugins/check_dns -H johnlord.comm -w 3 -c 6 command[check_swap]=/usr/lib64/nagios/plugins/check_swap -w 20% -c 10% command[check_all_mountpoints]=/usr/lib64/nagios/plugins/check_mountpoints -a command[check_total_procs]=/usr/lib64/nagios/plugins/check_procs -w 150 -c 200
Ubuntu / Debian sudo nano /etc/nagios/nrpe.cfg Below command lines let you monitor logged in users, system load, root filesystem usage, swap usage and the total number of the process with the help of Nagios plugins.
... ...
command[check_users]=/usr/lib/nagios/plugins/check_users -w 5 -c 10 command[check_load]=/usr/lib/nagios/plugins/check_load -w 15,10,5 -c 30,25,20 command[check_root]=/usr/lib/nagios/plugins/check_disk -w 20% -c 10% -p / command[check_swap]=/usr/lib/nagios/plugins/check_swap -w 20% -c 10% command[check_total_procs]=/usr/lib/nagios/plugins/check_procs -w 150 -c 200
In the above command definition -w stands for warning and -c stands for critical. Test Nagios Checks For example, execute the below command in another terminal to see the check result.
Ubuntu 18.04:
/usr/lib/nagios/plugins/check_procs -w 150 -c 200
Output:
PROCS WARNING: 190 processes | procs=190;150;200;0;
Nagios plugin will count running processes and will warn you if the process count is more than 150, or it will report you critical if the process count is more than 200, and at the same time, the output will state OK if the count is below 150.
You can adjust the alert level as per your requirements.
Change warning to 200 and critical to 250 for testing purposes. Now you will see an OK message.
/usr/lib/nagios/plugins/check_procs -w 200 -c 250 Output:
PROCS OK: 189 processes | procs=189;200;250;0; These command definitions have to be entered on a template file on the Nagios server host to enable the monitoring.
Restart the NRPE service.
systemctl start nrpe
systemctl enable nrpe
sudo systemctl restart nagios-nrpe-server Firewall Configure the firewall so that the Nagios server can able to reach the NRPE server running on a remote Linux host. Run these commands on a remote Linux machine.
FirewallD firewall-cmd --permanent --add-port=5666/tcp
firewall-cmd --reload
IP Tables iptables -I INPUT -p tcp --dport 5666 -m conntrack --ctstate NEW,ESTABLISHED -j ACCEPT
iptables -I OUTPUT -p tcp --sport 5666 -m conntrack --ctstate ESTABLISHED -j ACCEPT
/etc/init.d/iptables save
***********On Nagios Server Install NRPE plugin This NRPE plugin provides check_nrpe plugin which contacts the NRPE server on remote machines to check the services or resource.
CentOS / RHEL Nagios NRPE plugin is available in the EPEL repository for CentOS / RHEL. So, configure the EPEL repository your CentOS / RHEL system.
rpm -ivh https://dl.fedoraproject.org/pub/epel/epel-release-latest-8.noarch.rpm
rpm -ivh https://dl.fedoraproject.org/pub/epel/epel-release-latest-7.noarch.rpm
rpm -ivh https://dl.fedoraproject.org/pub/epel/epel-release-latest-6.noarch.rpm Use the following command to install the NRPE plugin on your machine.
yum -y install nagios-plugins-nrpe
Ubuntu / Debian Use the following command to install the NRPE plugin on your machine.
sudo apt install -y nagios-nrpe-plugin
Edit Configuration Edit the Nagios configuration file to include all .cfg files inside the /usr/local/nagios/etc/servers directory.
vim /usr/local/nagios/etc/nagios.cfg
sudo nano /usr/local/nagios/etc/nagios.cfg
Add or uncomment the following line.
cfg_dir=/usr/local/nagios/etc/servers Create a configuration directory.
mkdir /usr/local/nagios/etc/servers
sudo mkdir /usr/local/nagios/etc/servers
Add Command Definition Now it’s time to configure the Nagios server to monitor the remote client machine, and You’ll need to create a command definition in Nagios object configuration file to use the check_nrpe plugin.
Open the commands.cfg file.
CentOS / RHEL vi /usr/local/nagios/etc/objects/commands.cfg
Add the following Nagios command definition to the file.
define command{
command_name check_nrpe
command_line /usr/lib64/nagios/plugins/check_nrpe -H
define command{
command_name check_nrpe
command_line /usr/lib/nagios/plugins/check_nrpe -H
vim /usr/local/nagios/etc/servers/zabbix.johnlord.comm.cfg
sudo nano /usr/local/nagios/etc/servers/zabbix.johnlord.comm.cfg Copy the below content to the above file.
You can also use the following template and modify it according to your requirements. The following template is for monitoring logged in users, system load, disk usage (/ – partition), swap, and total process.
define host{
use linux-server
host_name zabbix.johnlord.comm
alias zabbix.johnlord.comm
address 192.168.0.47
}
define hostgroup{
hostgroup_name linux-server
alias Linux Servers
members zabbix.johnlord.comm
}
define service{
use local-service
host_name zabbix.johnlord.comm
service_description SWAP Uasge
check_command check_nrpe!check_swap
}
define service{
use local-service
host_name zabbix.johnlord.comm
service_description Root / Partition
check_command check_nrpe!check_root
}
define service{
use local-service
host_name zabbix.johnlord.comm
service_description Current Users
check_command check_nrpe!check_users
}
define service{
use local-service
host_name zabbix.johnlord.comm
service_description Total Processes
check_command check_nrpe!check_total_procs
}
define service{
use local-service
host_name zabbix.johnlord.comm
service_description Current Load
check_command check_nrpe!check_load
}
Verify Nagios for any errors.
/usr/local/nagios/bin/nagios -v /usr/local/nagios/etc/nagios.cfg
/usr/local/nagios/bin/nagios -v /usr/local/nagios/etc/nagios.cfg Restart the Nagios server.
systemctl restart nagios
sudo systemctl restart nagios Check Nagios Monitoring Go and check the Nagios web interface to view the new services we added just now.
LINK TO AUTOMATE NAGIOS DOCUMENTATION THRU ANSIBLE FOR NRPE CLIENT https://www.neteye-blog.com/2018/04/how-to-deploy-nrpe-on-centos-7-with-ansible/
define service{
use local-service
host_name apache.johnlord.comm
service_description SWAP Uasge
check_command check_nrpe!check_swap
}
define service{
use local-service
host_name apache.johnlord.comm
service_description Root / Partition
check_command check_nrpe!check_root
}
define service{
use local-service
host_name apache.johnlord.comm
service_description Current Users
check_command check_nrpe!check_users
}
define service{
use local-service
host_name apache.johnlord.comm
service_description Total Processes
check_command check_nrpe!check_total_procs
}
define service{
use local-service
host_name apache.johnlord.comm
service_description Current Load
check_command check_nrpe!check_load
}
host_name apache.johnlord.comm,jenkins.johnlord.comm,maven.johnlord.comm,git.johnlord.comm,ans.johnlord.comm,tomcat.johnlord.comm,sona.johnlord.comm,gradle.johnlord.comm,bitpost.johnlord.comm,nexus.johnlord.comm,k8s.johnlord.comm,ldap.johnlord.comm,zabbix.johnlord.comm,nessus.johnlord.comm,nginx.johnlord.comm,jira.johnlord.comm,dns.johnlord.comm,ipam.johnlord.comm,oracle.johnlord.comm
#!/bin/bash
yum update -y yum install epel-release vim wget java -y rpm -ivh https://dl.fedoraproject.org/pub/epel/epel-release-latest-7.noarch.rpm yum install -y nrpe nagios-plugins-all
Nagios object config [root@nagios ~]# cat /usr/local/nagios/etc/servers/maven.johnlord.comm.cfg define host{
use linux-server
host_name apache.johnlord.comm
alias apache.johnlord.comm
address 192.168.0.62
}
define host{
use linux-server
host_name maven.johnlord.comm
alias maven.johnlord.comm
address 192.168.0.48
}
define host{
use linux-server
host_name jenkins.johnlord.comm
alias jenkins.johnlord.comm
address 192.168.0.31
}
define host{
use linux-server
host_name git.johnlord.comm
alias git.johnlord.comm
address 192.168.0.58
}
define host{
use linux-server
host_name ans.johnlord.comm
alias ans.johnlord.comm
address 192.168.0.39
}
define host{
use linux-server
host_name tomcat.johnlord.comm
alias tomcat.johnlord.comm
address 192.168.0.36
}
define host{
use linux-server
host_name sona.johnlord.comm
alias sona.johnlord.comm
address 192.168.0.59
}
define host{
use linux-server
host_name gradle.johnlord.comm
alias gradle.johnlord.comm
address 192.168.0.52
}
define host{
use linux-server
host_name bitpost.johnlord.comm
alias bitpost.johnlord.comm
address 192.168.0.41
}
define host{
use linux-server
host_name nexus.johnlord.comm
alias nexus.johnlord.comm
address 192.168.0.35
}
define host{
use linux-server
host_name k8s.johnlord.comm
alias k8s.johnlord.comm
address 192.168.0.44
}
define host{
use linux-server
host_name ldap.johnlord.comm
alias ldap.johnlord.comm
address 192.168.0.51
}
define host{
use linux-server
host_name zabbix.johnlord.comm
alias zabbix.johnlord.comm
address 192.168.0.47
}
define host{
use linux-server
host_name nessus.johnlord.comm
alias nessus.johnlord.comm
address 192.168.0.49
}
define host{
use linux-server
host_name nginx.johnlord.comm
alias nginx.johnlord.comm
address 192.168.0.53
}
define host{
use linux-server
host_name jira.johnlord.comm
alias jira.johnlord.comm
address 192.168.0.42
}
define host{
use linux-server
host_name dns.johnlord.comm
alias dns.johnlord.comm
address 192.168.0.32
}
define host{
use linux-server
host_name ipam.johnlord.comm
alias ipam.johnlord.comm
address 192.168.0.63
}
define hostgroup{
hostgroup_name linux-server
alias Linux Servers
members apache.johnlord.comm
}
define service{
use local-service
host_name apache.johnlord.comm,jenkins.johnlord.comm,maven.johnlord.comm,git.johnlord.comm,ans.johnlord.comm,tomcat.johnlord.comm,sona.johnlord.comm,gradle.johnlord.comm,bitpost.johnlord.comm,nexus.johnlord.comm,k8s.johnlord.comm,ldap.johnlord.comm,zabbix.johnlord.comm,nessus.johnlord.comm,nginx.johnlord.comm,jira.johnlord.comm,dns.johnlord.comm,ipam.johnlord.comm
service_description SWAP Uasge
check_command check_nrpe!check_swap
}
define service{
use local-service
host_name apache.johnlord.comm,jenkins.johnlord.comm,maven.johnlord.comm,git.johnlord.comm,ans.johnlord.comm,tomcat.johnlord.comm,sona.johnlord.comm,gradle.johnlord.comm,bitpost.johnlord.comm,nexus.johnlord.comm,k8s.johnlord.comm,ldap.johnlord.comm,zabbix.johnlord.comm,nessus.johnlord.comm,nginx.johnlord.comm,jira.johnlord.comm,dns.johnlord.comm,ipam.johnlord.comm
service_description Root / Partition
check_command check_nrpe!check_root
}
define service{
use local-service
host_name apache.johnlord.comm,jenkins.johnlord.comm,maven.johnlord.comm,git.johnlord.comm,ans.johnlord.comm,tomcat.johnlord.comm,sona.johnlord.comm,gradle.johnlord.comm,bitpost.johnlord.comm,nexus.johnlord.comm,k8s.johnlord.comm,ldap.johnlord.comm,zabbix.johnlord.comm,nessus.johnlord.comm,nginx.johnlord.comm,jira.johnlord.comm,dns.johnlord.comm,ipam.johnlord.comm
service_description Current Users
check_command check_nrpe!check_users
}
define service{
use local-service
host_name apache.johnlord.comm,jenkins.johnlord.comm,maven.johnlord.comm,git.johnlord.comm,ans.johnlord.comm,tomcat.johnlord.comm,sona.johnlord.comm,gradle.johnlord.comm,bitpost.johnlord.comm,nexus.johnlord.comm,k8s.johnlord.comm,ldap.johnlord.comm,zabbix.johnlord.comm,nessus.johnlord.comm,nginx.johnlord.comm,jira.johnlord.comm,dns.johnlord.comm,ipam.johnlord.comm
service_description Total Processes
check_command check_nrpe!check_total_procs
}
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