centreon Linux: Complete IT Infrastructure Monitoring Solution Guide

Centreon is a powerful, open-source IT infrastructure monitoring platform built on top of Nagios Core. It provides a comprehensive web-based interface for monitoring networks, systems, applications, and services across your entire IT infrastructure. This guide covers everything you need to know about installing, configuring, and using Centreon on Linux systems.

What is Centreon?

Centreon is an enterprise-grade monitoring solution that combines the reliability of Nagios with a modern, user-friendly interface. It offers real-time monitoring, alerting, reporting, and performance analysis capabilities that help system administrators maintain optimal infrastructure performance.

Key Features of Centreon

• Web-based Interface: Modern, intuitive dashboard for monitoring management
• Real-time Monitoring: Continuous monitoring of hosts, services, and applications
• Advanced Alerting: Customizable notification systems via email, SMS, and webhooks
• Performance Analytics: Detailed graphs and reports for capacity planning
• Auto-discovery: Automatic detection and configuration of network devices
• Plugin Ecosystem: Extensive library of monitoring plugins
• High Availability: Support for redundant monitoring architectures

System Requirements

Before installing Centreon, ensure your Linux system meets the following requirements:

Installing Centreon on Linux

Installation on CentOS/RHEL

Follow these steps to install Centreon on CentOS or RHEL systems:

Step 1: Add Centreon Repository

# Install the Centreon repository
curl -L https://yum.centreon.com/standard/21.10/el7/stable/noarch/RPMS/centreon-release-21.10-1.el7.centos.noarch.rpm -o centreon-release.rpm
sudo yum install -y centreon-release.rpm

# Update package cache
sudo yum update -y

Step 2: Install Centreon Central Server

# Install Centreon and dependencies
sudo yum install -y centreon centreon-database

# Install MariaDB server
sudo yum install -y mariadb-server mariadb
sudo systemctl enable mariadb
sudo systemctl start mariadb

# Secure MariaDB installation
sudo mysql_secure_installation

Step 3: Configure Database

# Create Centreon databases
mysql -u root -p
CREATE DATABASE centreon;
CREATE DATABASE centreon_storage;
CREATE USER 'centreon'@'localhost' IDENTIFIED BY 'centreon_password';
GRANT ALL PRIVILEGES ON centreon.* TO 'centreon'@'localhost';
GRANT ALL PRIVILEGES ON centreon_storage.* TO 'centreon'@'localhost';
FLUSH PRIVILEGES;
EXIT;

Installation on Ubuntu/Debian

For Ubuntu or Debian systems, use the following installation process:

Step 1: Add Repository and Install

# Download and add Centreon repository key
wget -O- https://apt-key.centreon.com | sudo apt-key add -

# Add Centreon repository
echo "deb https://apt.centreon.com/repository/21.10/ $(lsb_release -sc) main" | sudo tee /etc/apt/sources.list.d/centreon.list

# Update package list
sudo apt update

# Install Centreon
sudo apt install -y centreon centreon-database mariadb-server

Initial Configuration

Web-based Setup Wizard

After installation, complete the setup using Centreon’s web interface:

1. Open your web browser and navigate to http://your-server-ip/centreon
2. Follow the setup wizard to configure database connections
3. Create the admin user account
4. Configure monitoring engine settings

Configure Apache Virtual Host

# Create Apache virtual host for Centreon
sudo cat << 'EOF' > /etc/httpd/conf.d/10-centreon.conf
<VirtualHost *:80>
    ServerName centreon.yourdomain.com
    DocumentRoot /usr/share/centreon/www/
    DirectoryIndex index.php

    <Directory "/usr/share/centreon/www">
        Options Indexes FollowSymLinks
        AllowOverride All
        Order allow,deny
        Allow from all
        Require all granted
    </Directory>
</VirtualHost>
EOF

# Restart Apache
sudo systemctl restart httpd

Configuring Monitoring

Adding Hosts for Monitoring

To monitor hosts with Centreon, follow these steps:

1. Using the Web Interface

1. Navigate to Configuration → Hosts → Hosts
2. Click Add to create a new host
3. Fill in the host details:

Host Name: web-server-01
Alias: Web Server 01
IP Address: 192.168.1.100
Templates: OS-Linux-SNMP-custom
Check Command: check_host_alive
Check Period: 24x7
Max Check Attempts: 3

2. Using Host Templates

Centreon provides pre-configured templates for common scenarios:

• OS-Linux-SNMP-custom: Linux servers with SNMP monitoring
• OS-Windows-SNMP-custom: Windows servers
• Net-SNMP-custom: Network devices
• App-Web-Apache-custom: Apache web servers

Configuring Services

Services represent specific checks performed on hosts:

# Example service configuration for CPU monitoring
Service Description: CPU
Check Command: check_nrpe!check_cpu
Normal Check Interval: 5 minutes
Retry Check Interval: 1 minute
Max Check Attempts: 3
Active Checks Enabled: Yes
Passive Checks Enabled: Yes

Monitoring Examples

Example 1: Monitoring Linux Server CPU Usage

Configure CPU monitoring for a Linux server using NRPE:

On the Monitored Host:

# Install NRPE and plugins
sudo yum install -y nrpe nagios-plugins-all

# Configure NRPE
sudo vim /etc/nagios/nrpe.cfg

# Add this line to allow Centreon server
allowed_hosts=127.0.0.1,192.168.1.50

# Add CPU check command
command[check_cpu]=/usr/lib64/nagios/plugins/check_cpu -w 80 -c 90

# Start NRPE service
sudo systemctl enable nrpe
sudo systemctl start nrpe

On the Centreon Server:

# Test the connection
/usr/lib/centreon/plugins/check_nrpe -H 192.168.1.100 -c check_cpu

# Expected output:
CPU OK - idle=85.2% user=8.1% nice=0.0% sys=6.7% iowait=0.0% irq=0.0% softirq=0.0%

Example 2: Network Device SNMP Monitoring

Monitor a network switch using SNMP:

# Test SNMP connectivity
snmpwalk -v2c -c public 192.168.1.10 1.3.6.1.2.1.1.5.0

# Configure in Centreon Web Interface:
Host Name: switch-01
IP Address: 192.168.1.10
SNMP Version: 2c
SNMP Community: public
Template: Net-SNMP-custom

Example 3: Web Service Monitoring

Monitor HTTP services and response times:

# Test HTTP check manually
/usr/lib/centreon/plugins/check_http -H www.example.com -p 80 -u /

# Service configuration:
Service Description: HTTP
Check Command: check_http!-H $HOSTADDRESS$ -p 80 -w 3 -c 5
Warning Threshold: 3 seconds
Critical Threshold: 5 seconds

Advanced Configuration

Setting Up Notifications

Configure email notifications for alerts:

1. Configure Email Settings

# Configure Postfix for email delivery
sudo yum install -y postfix
sudo systemctl enable postfix
sudo systemctl start postfix

# Test email functionality
echo "Test email from Centreon" | mail -s "Test" [email protected]

2. Create Notification Commands

In Centreon web interface, go to Configuration → Commands → Notifications:

Command Name: notify-host-by-email
Command Line: /usr/bin/printf "%b" "Notification Type: $NOTIFICATIONTYPE$\n\nHost: $HOSTNAME$\nState: $HOSTSTATE$\nAddress: $HOSTADDRESS$\nInfo: $HOSTOUTPUT$\n\nDate/Time: $LONGDATETIME$\n" | /bin/mail -s "Host $HOSTSTATE$ alert for $HOSTNAME$!" $CONTACTEMAIL$

Performance Tuning

Optimize Centreon for better performance:

Database Optimization

# Optimize MySQL/MariaDB configuration
sudo vim /etc/my.cnf.d/centreon.cnf

[mysqld]
innodb_buffer_pool_size = 2G
innodb_log_file_size = 512M
query_cache_size = 128M
max_connections = 500
table_open_cache = 4000

# Restart MariaDB
sudo systemctl restart mariadb

Monitoring Engine Tuning

# Adjust Nagios engine settings
sudo vim /etc/centreon-engine/centengine.cfg

# Increase concurrent checks
max_concurrent_checks=200

# Optimize check result processing
check_result_reaper_frequency=10
max_check_result_reaper_time=30

# Restart monitoring engine
sudo systemctl restart centengine

Monitoring Dashboard Usage

Understanding the Main Dashboard

The Centreon dashboard provides several key views:

• Tactical Overview: High-level status summary of all monitored objects
• Host Status: Real-time status of all monitored hosts
• Service Status: Detailed view of service checks and their states
• Performance Charts: Graphical representation of performance metrics

Using Filters and Views

Efficiently navigate large monitoring environments:

# Common filter examples:
- Host Group: "Linux Servers"
- Service State: "Critical"
- Host State: "Down"
- Last Check: "< 5 minutes"

Troubleshooting Common Issues

Connectivity Problems

Diagnose and resolve common connectivity issues:

# Test network connectivity
ping 192.168.1.100

# Test NRPE connection
telnet 192.168.1.100 5666

# Test SNMP connectivity
snmpwalk -v2c -c public 192.168.1.100 1.3.6.1.2.1.1.1.0

# Check firewall settings
sudo firewall-cmd --list-all
sudo iptables -L

Service Check Issues

Debug failing service checks:

# Check Centreon Engine logs
sudo tail -f /var/log/centreon-engine/centengine.log

# Test commands manually
sudo -u centreon-engine /usr/lib/centreon/plugins/check_ping -H 192.168.1.100 -w 3000.0,80% -c 5000.0,100%

# Verify plugin permissions
ls -la /usr/lib/centreon/plugins/

Best Practices

Security Hardening

• Use HTTPS: Configure SSL certificates for web interface
• Strong Authentication: Implement LDAP or Active Directory integration
• Network Segmentation: Place monitoring server in dedicated network segment
• Regular Updates: Keep Centreon and underlying OS updated

Monitoring Strategy

• Start Simple: Begin with basic host and service checks
• Use Templates: Leverage host and service templates for consistency
• Monitor Dependencies: Configure parent-child relationships
• Set Appropriate Thresholds: Avoid alert fatigue with realistic warning levels

Backup and Recovery

# Backup Centreon configuration
sudo tar -czf centreon-backup-$(date +%Y%m%d).tar.gz \
  /etc/centreon \
  /etc/centreon-engine \
  /etc/centreon-broker

# Backup databases
mysqldump -u root -p centreon > centreon-db-$(date +%Y%m%d).sql
mysqldump -u root -p centreon_storage > centreon-storage-$(date +%Y%m%d).sql

Conclusion

Centreon provides a comprehensive monitoring solution that scales from small environments to enterprise infrastructures. Its combination of powerful monitoring capabilities, intuitive web interface, and extensive customization options makes it an excellent choice for IT infrastructure monitoring on Linux systems.

By following this guide, you now have the knowledge to install, configure, and effectively use Centreon for monitoring your IT infrastructure. Remember to start with basic monitoring and gradually expand your monitoring scope as you become more familiar with the platform.

Regular maintenance, proper configuration management, and adherence to monitoring best practices will ensure your Centreon installation provides reliable infrastructure monitoring for years to come.