Comprehensive Guide to Monitoring Oracle Linux 9 with NCPA in Nagios XI

Efficient Linux server monitoring is essential for ensuring system stability, performance, and proactive issue resolution. The Nagios Cross Platform Agent (NCPA) offers a powerful, agent-based solution for monitoring Oracle Linux 9 with Nagios XI, providing deep insights into CPU usage, memory, disk space, and system processes.

This guide walks you through the step-by-step installation and configuration of NCPA on Oracle Linux 9, enabling seamless integration with Nagios XI for real-time monitoring and proactive alerts.

Prerequisites

Before proceeding, ensure the following:

• A system running Oracle Linux 9 with root or sudo privileges.
• Nagios XI installed and accessible, with the NCPA Wizard enabled.
• A stable internet connection for package downloads.

Step 1: Install NCPA on Oracle Linux 9

There are two methods to install NCPA on Oracle Linux 9: using the Nagios repository or manually installing the RPM package.

Method 1: Using the Nagios Repository (Recommended)

To install NCPA using the Nagios repository, follow these steps:

1. Install the repository:

sudo rpm -Uvh https://repo.nagios.com/nagios/9/nagios-repo-9-2.el9.noarch.rpm

Note: Verify the latest version at repo.nagios.com if 9-2 is outdated.

2. Enable required repositories:

sudo yum install epel-release -y
sudo yum config-manager --set-enabled ol9_codeready_builder

3. Update your package list:

sudo yum update -y

4. Install NCPA:

sudo dnf install ncpa -y

5. Verify the installation:

 rpm -q ncpa

Expected output: ncpa-3.1.1-1.el9.x86_64 (version may vary).

Method 2: Manual RPM Installation

If you prefer to install NCPA manually, follow these steps:

1. Download the latest NCPA RPM package:

cd /tmp
wget https://assets.nagios.com/downloads/ncpa3/ncpa-latest.rpm

Note: Check nagios.com/ncpa for the latest version.

2. Install the package using rpm:

sudo rpm -ivh /tmp/ncpa-latest.rpm

Step 2: Configure NCPA

After installation, configure NCPA by editing its configuration file to set your API token:

sudo nano /usr/local/ncpa/etc/ncpa.cfg

Find the line:

community_string = mytoken

Replace mytoken with a secure API token of your choice.

Save the file (CTRL + X, then Y, and Enter).

Step 3: Enable and Start the NCPA Service

Restart and enable the service:

sudo systemctl restart ncpa_listener
sudo systemctl enable ncpa_listener

Check if the service is running:

sudo systemctl status ncpa

Look for Active: active (running). Note: The service is ncpa, not ncpa_listener.

Step 4: Configure Firewall Rules

If firewalld is enabled on your system, allow traffic on port 5693 (default NCPA port):

sudo firewall-cmd --zone=public --add-port=5693/tcp --permanent
sudo firewall-cmd --reload

Confirm firewall rules:

sudo firewall-cmd --list-ports

Step 5: Test NCPA Installation

After configuring the firewall, confirm that NCPA is accessible by navigating to:

https://<NCPA_IP_Address>:5693/

Since NCPA uses a self-signed certificate, your browser may display a warning. Click Advanced > Proceed to continue.

You should see the NCPA login page. Enter the API token you configured earlier and click Log In.

curl -k https://localhost:5693/api

Step 6: Add Oracle Linux 9 Host to Nagios XI Using NCPA Wizard

1. Log in to Nagios XI.

2. Navigate to Configure > Run a configuring wizard.

3. Search for and select NCPA.

4. Enter the Oracle Linux 9 server’s IP address and API token.

5. Click Next, select the system metrics to monitor (CPU, memory, disk, network traffic, etc.).

6. Apply the configuration and verify that Nagios XI is collecting data.

Common Issues & Fixes

NCPA Service is Not Running

Check logs for errors:

sudo journalctl -u ncpa --no-pager | tail -20

Restart NCPA if necessary:

sudo systemctl restart ncpa

Host Appears “Down” in Nagios XI

• Check firewall rules: sudo firewall-cmd --list-ports
• Ensure NCPA is running: sudo systemctl status ncpa
• Verify Nagios XI configuration

Incorrect API Token Error

• Confirm the correct API token is set in ncpa.cfg
• Restart the NCPA service after changes

Conclusion

You have successfully installed and configured NCPA on Oracle Linux 9 for monitoring with Nagios XI. This setup allows efficient tracking of system performance metrics and ensures proactive issue resolution.

For further assistance, refer to the Nagios Support Forum or the Nagios Knowledgebase.