Prerequisites

Ensure you have the following:

• An AlmaLinux 9 server with root or sudo access
• A running Nagios Log Server 2024R2 instance
• Network connectivity between the AlmaLinux server and Log Server (default port 5544 open)
• SELinux disabled or properly configured for rsyslog

Step 1: Access Log Source Setup in Nagios Log Server

1. Log into your Nagios Log Server web interface.

2. Click the + button in the left sidebar and the one at the bottom.

Step 2: Run the Auto-Configuration Script on AlmaLinux 9

1. Copy the setup script command shown in the Nagios interface. It looks similar to:

curl -sS -O http://<logserver-ip>/nagioslogserver/scripts/setup-linux.sh
sudo bash setup-linux.sh -s <logserver-ip> -p 5544

curl -sS -O http://<logserver-ip>/nagioslogserver/scripts/setup-linux.sh
sudo bash setup-linux.sh -s <logserver-ip> -p 5544

• Replace <logserver-ip> with the IP or DNS name of your Nagios Log Server.

2. Example Output:

curl -sS -O http://192.168.1.123/nagioslogserver/scripts/setup-linux.sh 
sudo bash setup-linux.sh -s 192.168.0.31 -p 5544

curl -sS -O http://192.168.1.123/nagioslogserver/scripts/setup-linux.sh 
sudo bash setup-linux.sh -s 192.168.0.31 -p 5544

3. Confirm the script output shows successful configuration:

• “Detected rsyslog…”
• “rsyslog configuration check passed.”
• “rsyslog is running with the new configuration.”

Step 3: Verify Logs Are Reaching Nagios Log Server

1. In the Nagios Log Server web UI, enter the AlmaLinux server’s IP under Verify Incoming Logs.

2. Alternatively, go to Dashboards > Nagios Log Server Search and run:

host.ip:<AlmaLinux-IP>

host.ip:<AlmaLinux-IP>

3. To test log transmission, run:

logger This is a test log entry

logger This is a test log entry

4. Verify the entry appears in the Nagios Log Server interface.

Optional: Manual rsyslog Configuration (Advanced)

If you prefer not to use the script, follow these steps:

1. Create a custom rsyslog config file:

sudo nano /etc/rsyslog.d/.conf

sudo nano /etc/rsyslog.d/.conf

2. Add the following content (replace IP and port as needed):

# ### begin forwarding rule ### NAGIOSLOGSERVER
$WorkDirectory /var/lib/rsyslog
$ActionQueueFileName fwdRule1
$ActionQueueMaxDiskSpace 1g
$ActionQueueSaveOnShutdown on
$ActionQueueType LinkedList
$ActionResumeRetryCount -1
*.* @@192.168.1.123:5544
# ### end of the forwarding rule ###

# ### begin forwarding rule ### NAGIOSLOGSERVER
$WorkDirectory /var/lib/rsyslog
$ActionQueueFileName fwdRule1
$ActionQueueMaxDiskSpace 1g
$ActionQueueSaveOnShutdown on
$ActionQueueType LinkedList
$ActionResumeRetryCount -1
*.* @@192.168.1.123:5544
# ### end of the forwarding rule ###

3. Restart rsyslog:

sudo systemctl restart rsyslog

sudo systemctl restart rsyslog

4. Verify logs are received as in Step 3.

Step 4: Adding More Log Sources

Use the + Add Log Source button to configure:

• Network Device
• Application Logs
• Archived logs

Conclusion

You’ve successfully configured AlmaLinux 9 to send logs to Nagios Log Server 2024R2. Whether using the automatic script or manual configuration, this setup allows centralized logging, simplifying monitoring and analysis. For advanced use cases, explore custom filtering, alerting, and integrations in the Nagios Log Server interface.

Resource

• Nagios Log Server Knowledgebase
• Nagios Support Forum
• AlmaLinux Documentation

This guide walks you through the installation and configuration process of NCPA on AlmaLinux 8, enabling comprehensive system monitoring through Nagios XI.

Prerequisites

Before proceeding, ensure you have:

• An AlmaLinux 8 system with root or sudo privileges
• Nagios XI installed and accessible, with the NCPA Wizard enabled
• A stable internet connection for package downloads
• SELinux set to enforcing or permissive (check with getenforce; adjust if needed)

Step 1: Install the Nagios Repository

The recommended method for installing NCPA on AlmaLinux 8 is using the Nagios repository:

sudo rpm -Uvh https://repo.nagios.com/nagios/8/nagios-repo-8-1.el8.noarch.rpm
sudo yum update -y

sudo rpm -Uvh https://repo.nagios.com/nagios/8/nagios-repo-8-1.el8.noarch.rpm
sudo yum update -y

After adding the repository, refresh your package list:

sudo dnf clean all
sudo dnf update -y

sudo dnf clean all
sudo dnf update -y

Step 2: Install NCPA on AlmaLinux 8

Install the NCPA agent using:

sudo dnf install ncpa -y

sudo dnf install ncpa -y

Verify installation:

rpm -q ncpa

rpm -q ncpa

Expected output: ncpa-<version>.el8.x86_64

Step 3: Configure NCPA

Edit the NCPA configuration file to set your API token:

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

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

Find the line:

community_string = mytoken

community_string = mytoken

Replace mytoken with a strong, unique token (e.g., K9pL3mX7vR2tQ8nJ). Save and close.

Step 4: Enable and Start the NCPA Service

Ensure NCPA runs at boot and starts now:

sudo systemctl enable ncpa
sudo systemctl start ncpa
sudo systemctl status ncpa

sudo systemctl enable ncpa
sudo systemctl start ncpa
sudo systemctl status ncpa

Confirm active (running) is displayed.

Step 5: Configure Firewall Rules

If firewalld is active, open port 5693:

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

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

Verify:

sudo firewall-cmd --list-ports

sudo firewall-cmd --list-ports

Step 6: Test NCPA Installation

Verify access to NCPA by visiting:

https://<AlmaLinux8-IP>:5693/

https://<AlmaLinux8-IP>:5693/

Accept the browser’s self-signed certificate warning. Enter your API token and log in.

Step 7: Add AlmaLinux 8 Host to Nagios XI Using NCPA Wizard

1. Log into Nagios XI.

2. Navigate to Configure > Configuration Wizards.

3. Search for and select NCPA.

4. Enter the AlmaLinux 8 server’s IP and the API token.

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

6. Apply configuration and verify data collection.

Common Issues & Fixes

NCPA Service is Not Running

Check logs:

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

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

Restart NCPA if needed:

sudo systemctl restart ncpa

sudo systemctl restart ncpa

Host Appears “Down” in Nagios XI

Check firewall rules:

sudo firewall-cmd --list-ports

sudo firewall-cmd --list-ports

Check NCPA status:

sudo systemctl status ncpa

sudo systemctl status ncpa

Verify Nagios XI configuration.

Incorrect API Token Error

Ensure correct token is set in ncpa.cfg. Restart NCPA after updates:

sudo systemctl restart ncpa

sudo systemctl restart ncpa

Conclusion

You have successfully installed and configured NCPA on AlmaLinux 8 for monitoring with Nagios XI. This setup enables efficient tracking of system performance metrics and supports proactive issue resolution.

For additional support:

• Nagios Support Forum
• Nagios Knowledgebase