In this guide, you’ll learn how to configure Oracle Linux 9 to forward logs to Nagios Log Server 2024R2 using rsyslog. By setting up seamless log transmission, you’ll gain real-time visibility into system events, detect anomalies faster, and strengthen your overall monitoring strategy. Let’s dive in and get started!

Prerequisites

Before proceeding, ensure you have the following:

• Access to a Nagios Log Server instance (latest stable release recommended)
• A system running Oracle Linux 9
• Root or sudo privileges on your Oracle Linux machine
• Network connectivity between Oracle Linux and Nagios Log Server (ensure port 5544 is open)

Step 1: Add a New Log Source in Nagios Log Server

1. Login to Nagios Log Server:
   • Open your web browser and navigate to your Nagios Log Server instance.
   • Log in using your administrator credentials.
2. Navigate to Log Source Setup:
   • On the Home page, locate and click the + Linux button in the upper right.

3. Alternatively, click + Add Log Source in the navigation bar and select Linux.

Step 2: Configuring the Linux Log Source

1. Download and Run the Setup Script

The Linux Source Setup page provides a code block with a pre-configured command.

If curl is not installed, run:

sudo dnf install -y curl

sudo dnf install -y curl

Then, run the following command (replace <nagios-log-server-address> with your actual server IP or hostname):

curl -sS -O http://<nagios-log-server-address>/nagioslogserver/scripts/setup-linux.sh
sudo bash setup-linux.sh -s <nagios-log-server-address> -p 5544

curl -sS -O http://<nagios-log-server-address>/nagioslogserver/scripts/setup-linux.sh
sudo bash setup-linux.sh -s <nagios-log-server-address> -p 5544

• -s specifies the Log Server address
• -p 5544 is the default port for syslog ingestion

2. Verify the Script Execution

You should see an output like:

Detected rsyslog 8.2102.0
Detected rsyslog work directory /var/lib/rsyslog
Destination Log Server: 192.168.0.31:5544
Creating /etc/rsyslog.d/99-nagioslogserver.conf...
SELinux is disabled.
rsyslog configuration check passed.
Restarting rsyslog service with 'service'...
rsyslog is running with the new configuration.

Detected rsyslog 8.2102.0
Detected rsyslog work directory /var/lib/rsyslog
Destination Log Server: 192.168.0.31:5544
Creating /etc/rsyslog.d/99-nagioslogserver.conf...
SELinux is disabled.
rsyslog configuration check passed.
Restarting rsyslog service with 'service'...
rsyslog is running with the new configuration.

Check the Nagios Log Server dashboard to confirm that logs are being received.

Step 3: Confirming Log Reception

1. Navigate to the Dashboards section in Nagios Log Server.
2. In the Search panel, run a query for the new source IP:

host.ip:<Oracle Linux 9 IP>

host.ip:<Oracle Linux 9 IP>

3. Send a test log entry from the Linux machine:

logger "This is a test log entry"

logger "This is a test log entry"

If successful, the test entry will appear in the results.

Step 4: Accessing the Setup Script on the Server

The script is stored on the Nagios Log Server here:

/var/www/html/nagioslogserver/www/scripts/setup-linux.sh

/var/www/html/nagioslogserver/www/scripts/setup-linux.sh

This script can be accessed directly via a browser or edited via SSH for custom changes.

Step 5: Manual Setup (Optional)

If you prefer to configure manually:

1. Create a configuration file:

sudo nano /etc/rsyslog.conf

sudo nano /etc/rsyslog.conf

2. Add the following lines at the begin forwarding rule section:

# ### begin forwarding rule ### NAGIOSLOGSERVER
$WorkDirectory /var/lib/rsyslog
$ActionQueueFileName fwdRule1
$ActionQueueMaxDiskSpace 1g
$ActionQueueSaveOnShutdown on
$ActionQueueType LinkedList
$ActionResumeRetryCount -1
*.* @@192.168.1.113:5544
# ### end of the forwarding rule ###

# ### begin forwarding rule ### NAGIOSLOGSERVER
$WorkDirectory /var/lib/rsyslog
$ActionQueueFileName fwdRule1
$ActionQueueMaxDiskSpace 1g
$ActionQueueSaveOnShutdown on
$ActionQueueType LinkedList
$ActionResumeRetryCount -1
*.* @@192.168.1.113:5544
# ### end of the forwarding rule ###

3. Restart rsyslog:

sudo /etc/init.d/rsyslog restart

sudo /etc/init.d/rsyslog restart

Step 6: Adding More Log Sources

Use the + Add Log Source button to configure additional sources such as:

• Windows Event Logs
• Application Logs
• Archived Log Files

Both scripted and manual setup options are available. Manual setup allows for deeper customization by editing config files directly.

Troubleshooting Tips

1. Check rsyslog Status:

sudo systemctl status rsyslog

sudo systemctl status rsyslog

Start it if it’s not running:

sudo systemctl start rsyslog

sudo systemctl start rsyslog

2. Check Connectivity: Ensure port 5544 is open and reachable.
3. Check Firewall:

sudo firewall-cmd --zone=public --add-port=5544/tcp --permanent
sudo firewall-cmd --reload

sudo firewall-cmd --zone=public --add-port=5544/tcp --permanent
sudo firewall-cmd --reload

4. Review Logs:

cat /var/log/messages | grep rsyslog

cat /var/log/messages | grep rsyslog

On Nagios Log Server:

tail -f /var/log/logserver/nagios.log

tail -f /var/log/logserver/nagios.log

Conclusion

You’ve successfully configured Oracle Linux 9 to forward logs to Nagios Log Server 2024R2. This setup gives you real-time visibility into system logs, performance events, and security data—essential for proactive system administration.

Explore additional sources and alerting options in Nagios Log Server for an even more powerful monitoring setup.

For additional resources:

• Nagios Knowledgebase
• Nagios Support Forum
• Nagios Library

In this guide, we’ll walk you through the step-by-step installation and configuration of SNMP on Oracle Linux 9, ensuring seamless integration with Nagios XI for efficient and proactive monitoring.

Prerequisites

Before proceeding, ensure the following:

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

Step 1: Install SNMP on Oracle Linux 9

To install SNMP and the required libraries, update the system first:

sudo yum update -y

sudo yum update -y

Then, install net-snmp:

sudo yum install net-snmp -y

sudo yum install net-snmp -y

Verify the installation:

snmpd -v

snmpd -v

This confirms that SNMP is correctly installed on the system.

Step 2: Configure SNMP Access

SNMP v2c Configuration

To configure SNMP v2c, create a backup of the existing configuration:

sudo cp /etc/snmp/snmpd.conf /etc/snmp/snmpd.conf.bak

sudo cp /etc/snmp/snmpd.conf /etc/snmp/snmpd.conf.bak

Now, edit the SNMP configuration file:

sudo nano /etc/snmp/snmpd.conf

sudo nano /etc/snmp/snmpd.conf

Find and modify the following line to define the community string and allow access from your Nagios XI server (replace Str0ngC0mmunity with your desired community string and 10.25.5.12 with your Nagios XI server’s IP address):

rocommunity Str0ngC0mmunity 10.25.5.12

rocommunity Str0ngC0mmunity 10.25.5.12

Save the file and restart the SNMP service:

sudo systemctl restart snmpd.service

sudo systemctl restart snmpd.service

SNMP v3 Configuration (More Secure)

To configure SNMP v3, create an SNMP user with authentication and encryption:

sudo net-snmp-create-v3-user -ro -a SHA -A Str0ng@uth3ntic@ti0n -x AES -X Str0ngPriv@cy nagios

sudo net-snmp-create-v3-user -ro -a SHA -A Str0ng@uth3ntic@ti0n -x AES -X Str0ngPriv@cy nagios

• -a SHA → Specifies SHA for authentication (MD5 is also supported but less secure).
• -x AES → Enables AES encryption (DES is another option but less secure).

Restart the SNMP service:

sudo systemctl restart snmpd.service

sudo systemctl restart snmpd.service

Step 3: Configure Firewall Rules

If firewalld is enabled on your system, allow SNMP traffic on UDP port 161:

sudo firewall-cmd --zone=public --add-port=161/udp --permanent
sudo firewall-cmd --reload

sudo firewall-cmd --zone=public --add-port=161/udp --permanent
sudo firewall-cmd --reload

Confirm firewall rules:

sudo firewall-cmd --list-ports

sudo firewall-cmd --list-ports

Step 4: Enable SNMP Service on Boot

To ensure SNMP starts automatically at boot, run:

sudo systemctl enable snmpd.service

sudo systemctl enable snmpd.service

Step 5: Test SNMP Communication

To test if SNMP is responding correctly, run the following commands from your Nagios XI server.

For SNMP v2c:

snmpwalk -v2c -c Str0ngC0mmunity 10.25.5.12

snmpwalk -v2c -c Str0ngC0mmunity 10.25.5.12

For SNMP v3:

snmpwalk -v3 -u nagios -l authPriv -a SHA -A Str0ng@uth3ntic@ti0n -x AES -X Str0ngPriv@cy 10.25.5.12

snmpwalk -v3 -u nagios -l authPriv -a SHA -A Str0ng@uth3ntic@ti0n -x AES -X Str0ngPriv@cy 10.25.5.12

Expected Output (Example)

iso.3.6.1.2.1.1.1.0 = STRING: "Linux myserver 5.15.0-100.el9.x86_64"
iso.3.6.1.2.1.1.3.0 = Timeticks: (100032) 0:16:40.32

iso.3.6.1.2.1.1.1.0 = STRING: "Linux myserver 5.15.0-100.el9.x86_64"
iso.3.6.1.2.1.1.3.0 = Timeticks: (100032) 0:16:40.32

If the command does not return data, review SNMP configuration and firewall settings.

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

1. Log in to Nagios XI.

2. Navigate to Configure > Run a Configuring Wizard.

3. Search for and select Linux SNMP Wizard.

4. Enter the Oracle Linux 9 server’s IP address and SNMP credentials.

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 SNMP data.

Host Appears “Down” in Nagios XI

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

Incorrect SNMP Credentials Error

• Confirm the correct community string (SNMP v2c) or authentication details (SNMP v3).
• Restart the SNMP service after changes.

Conclusion

You have successfully installed and configured SNMP on Oracle Linux 9 for monitoring with Nagios XI. This setup provides a robust, agentless solution for tracking system performance metrics and ensuring proactive issue resolution.

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

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

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

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

3. Update your package list:

sudo yum update -y

sudo yum update -y

4. Install NCPA:

sudo dnf install ncpa -y

sudo dnf install ncpa -y

5. Verify the installation:

 rpm -q ncpa

 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

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

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

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

Find the line:

community_string = mytoken

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

sudo systemctl restart ncpa_listener
sudo systemctl enable ncpa_listener

Check if the service is running:

sudo systemctl status ncpa

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

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

Confirm firewall rules:

sudo firewall-cmd --list-ports

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/

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

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

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

Restart NCPA if necessary:

sudo systemctl restart ncpa

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.