Redhat Enterprise Linux – Nagios Library https://library.nagios.com Complete Nagios monitoring resources and documentation Thu, 02 Apr 2026 18:16:00 +0000 en-US hourly 1 https://wordpress.org/?v=6.9.4 https://library.nagios.com/wp-content/uploads/2024/11/Nagios-Blue-N.svg Redhat Enterprise Linux – Nagios Library https://library.nagios.com 32 32 Sending Logs from RHEL 9 to Nagios Log Server R2 https://library.nagios.com/documentation/sending-logs-from-rhel-9-to-nagios-log-server-r2/ Fri, 28 Mar 2025 16:25:30 +0000 https://library.nagios.com/?p=53708 Nagios Log Server R2 introduces a robust logging system, simplifying the centralization and analysis of logs from multiple sources. This guide demonstrates how to configure a RHEL 9 machine to send its logs to the Nagios Log Server R2 using both automatic and manual methods.

Getting Started

Once configured, logs typically found in /var/log/messages will be forwarded to Nagios Log Server R2, enabling centralized monitoring and alerting.

Automatic Setup Using a Script

The simplest way to configure log forwarding is by using the provided setup script. This method requires rsyslog to be installed on your RHEL 9 system.

Steps to Run the Script:

1. Ensure Rsyslog is Installed:

sudo dnf install rsyslog -y
sudo systemctl enable --now rsyslog

2. Download the script from the Nagios Log Server R2:

curl -sS -O http://192.168.1.49/nagioslogserver/scripts/setup-linux.sh

3. Execute the Script to Configure Rsyslog:

sudo bash setup-linux.sh -s 192.168.1.49 -p 5544
  • Replace 192.168.1.49 with the IP address of your Nagios Log Server R2.
  • The -p 5544 option specifies the port for log transmission.

Manual Setup Using Rsyslog Configuration

For greater control over configurations, follow these manual setup steps:

1. Edit Rsyslog Configuration:

sudo nano /etc/rsyslog.d/99-nagios.conf

2. Add the Following Configuration:

*.* @@192.168.1.49:5544
  • Replace 192.168.1.49 with the IP address of your Nagios Log Server R2.
  • The @@ symbol indicates TCP transmission; use @ for UDP if required.

3. Restart Rsyslog to Apply Changes:

sudo systemctl restart rsyslog

4. Verify Rsyslog Status:

sudo systemctl status rsyslog

Receiving Logs in Log Server

On your Log Server’s GUI, click Add Log Source.

Screenshot 2025 03 21 131259 1
Nagios Log Server home page

Click Linux.

Screenshot 2025 03 21 131443 1
Add log source

Type in your machine’s IP address to see if you are receiving logs. If it’s working, the interface will confirm that logs are being received.

Screenshot 2025 03 21 132800 1
Verify incoming logs

Conclusion

Whether using the automatic script or manual configuration, forwarding logs from RHEL 9 to Nagios Log Server R2 ensures centralized log management for improved monitoring and alerting. Choose the method that best fits your deployment requirements.

]]> Efficient Server Monitoring with NCPA and Nagios XI on RHEL 9 https://library.nagios.com/monitoring/efficient-server-monitoring-with-ncpa-and-nagios-xi-on-rhel-9/ Fri, 28 Mar 2025 16:11:37 +0000 https://library.nagios.com/?p=53492 Effective server monitoring is crucial for maintaining optimal system performance and addressing issues before they escalate. The Nagios Cross-Platform Agent (NCPA) is a lightweight, agent-based tool that simplifies real-time monitoring for Linux systems like Red Hat Enterprise Linux (RHEL) 9. Unlike SNMP, NCPA uses a secure, RESTful API to collect detailed system metrics, offering a powerful and secure solution for integration with Nagios XI. This guide will walk you through the installation and configuration process of NCPA on RHEL 9, enabling comprehensive system monitoring through Nagios XI.

Prerequisites

Before proceeding, make sure you have:

  • A RHEL 9 system with root or sudo privileges.
  • Nagios XI is 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 RHEL 9 is by using the Nagios repository. To add the repository, run:

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

After adding the repository, update your package list:

sudo dnf clean all
sudo dnf update -y

Step 2: Install NCPA on RHEL 9

Once the repository is set up, install the NCPA agent using:

sudo dnf install ncpa -y

Verify the installation:

rpm -q ncpa

Expected output:

ncpa-.el9.x86_64 (e.g., ncpa-3.1.1-1.el9.x86_64)

Step 3: Configure NCPA

After installation, configure NCPA by editing the 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 strong, unique token (e.g., K9pL3mX7vR2tQ8nJ), ensuring it is not predictable for security reasons.

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

Step 4: Enable and Start the NCPA Service

To ensure NCPA runs automatically at boot and starts immediately, run:

sudo systemctl enable ncpa
sudo systemctl start ncpa

Check if the service is running:

sudo systemctl status ncpa

Confirm that the output shows Active: active (running).

Step 5: Configure Firewall Rules

If firewalld is active (check with sudo systemctl status firewalld), allow NCPA traffic on port 5693:

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

Confirm firewall rules:

sudo firewall-cmd --list-ports

Step 6: 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.

Step 7: Add RHEL 9 Host to Nagios XI Using NCPA Wizard

Log in to Nagios XI.

Navigate to Configure > Configuring Wizard.

image 17
Config wizards

Search for and select NCPA.

image 18
wizards page

Enter the RHEL 9 server’s IP address and the API token.

image 19
NCPA wizard

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

Apply the configuration and verify that Nagios XI is collecting data from your RHEL 9 host.

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 the Nagios XI configuration.

Incorrect API Token Error

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

Conclusion

You have successfully installed and configured NCPA on RHEL 9 for monitoring with Nagios XI. This setup enables you to efficiently track system performance metrics and ensure proactive issue resolution.

]]> Comprehensive SNMP Monitoring of AlmaLinux 8 with Nagios XI https://library.nagios.com/tutorials/comprehensive-snmp-monitoring-of-almalinux-8-with-nagios-xi/ Thu, 27 Mar 2025 14:51:04 +0000 https://library.nagios.com/?p=53512 Ensuring the health and performance of Linux servers is crucial for maintaining a stable and efficient IT environment. Simple Network Management Protocol (SNMP) provides a lightweight, agentless solution for monitoring AlmaLinux 8 with Nagios XI, allowing administrators to track critical system metrics without installing additional software.

This guide will take you through the complete process of setting up SNMP on AlmaLinux 8, integrating it with Nagios XI, and enabling real-time monitoring for proactive issue resolution and improved system reliability.

Prerequisites

Before proceeding, ensure the following:

  • An AlmaLinux 8 system 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 AlmaLinux 8

  1. To install SNMP and the required libraries, run:
sudo dnf install net-snmp net-snmp-utils -y
  1. After installation, verify the installed version:
snmpd -v

Step 2: Configure SNMP Access

SNMP v2c Configuration

  1. Create a backup of the existing configuration:
sudo cp /etc/snmp/snmpd.conf /etc/snmp/snmpd.conf.bak
  1. Edit the SNMP configuration file:
sudo nano /etc/snmp/snmpd.conf
  1. Replace or update the line with your community string and Nagios XI IP:
rocommunity Str0ngC0mmunity 10.25.5.12
  1. Save the file and restart SNMP:
sudo systemctl restart snmpd.service

SNMP v3 Configuration (More Secure)

  1. Stop the SNMP service temporarily:
sudo systemctl stop snmpd.service
  1. 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
  1. Restart the SNMP service:
sudo systemctl restart snmpd.service

Step 3: Configure Firewall Rules

  1. If firewalld is active, allow SNMP traffic on UDP port 161:
sudo firewall-cmd --zone=public --add-port=161/udp --permanent
sudo firewall-cmd --reload
  1. Confirm firewall rules:
sudo firewall-cmd --list-ports

Step 4: Enable SNMP Service on Boot

To ensure SNMP starts automatically at boot:

sudo systemctl enable snmpd.service

Step 5: Test SNMP Communication

From your Nagios XI server:

For SNMP v2c:

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

Expected Output (Example):

iso.3.6.1.2.1.1.1.0 = STRING: "Linux almalinux8 ..."

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

Step 6: Add AlmaLinux 8 Host to Nagios XI Using SNMP Wizard

1. Log in to Nagios XI

2. Navigate to Configure > Run a configuring wizard

Screenshot 2025 03 12 083824 10
configuration wizard

3. Search for and select Linux SNMP wizard

Linux SNMP 8
Linux SNMP

4. Enter the AlmaLinux 8 server’s IP address and SNMP credentials

Linux SNMP step 1 8
AlmaLinux 8 credentials

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

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

Common Issues & Fixes

SNMP Service is Not Running

Check logs for errors:

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

Restart SNMP if necessary:

sudo systemctl restart snmpd.service

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’ve successfully configured SNMP on AlmaLinux 8 for agentless monitoring with Nagios XI, providing real-time system insights. For advanced setups, explore custom SNMP OIDs or additional Nagios XI plugins.

For support:

]]> Setting Up NCPA for Monitoring AlmaLinux 8 in Nagios XI https://library.nagios.com/tutorials/setting-up-ncpa-for-monitoring-almalinux-8-in-nagios-xi/ Thu, 27 Mar 2025 13:02:15 +0000 https://library.nagios.com/?p=53490 Efficient server monitoring is crucial for maintaining optimal system performance and minimizing downtime. The Nagios Cross-Platform Agent (NCPA) is a lightweight, agent-based tool that simplifies real-time monitoring for Linux systems like AlmaLinux 8. Unlike SNMP, NCPA leverages a secure, RESTful API to collect detailed system metrics, making it a powerful and secure monitoring solution for integration with Nagios XI.

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

After adding the repository, refresh your package list:

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

Verify installation:

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

Find the line:

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

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

Verify:

sudo firewall-cmd --list-ports

Step 6: Test NCPA Installation

Verify access to NCPA by visiting:

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.

NCPA 7
NCPA

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

rhel 3
AlmaLinux 8 Credentials

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

Restart NCPA if needed:

sudo systemctl restart ncpa

Host Appears “Down” in Nagios XI

Check firewall rules:

sudo firewall-cmd --list-ports

Check NCPA status:

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

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:

]]> Monitoring AlmaLinux 9 with SNMP in Nagios XI: A Step-by-Step Guide https://library.nagios.com/tutorials/monitoring-almalinux-9-with-snmp-in-nagios-xi-a-step-by-step-guide/ Wed, 26 Mar 2025 19:16:57 +0000 https://library.nagios.com/?p=53476 Effective Linux server monitoring is essential for ensuring performance and reducing downtime. Simple Network Management Protocol (SNMP) provides an agentless solution to monitor AlmaLinux 9 servers using Nagios XI.

This guide walks you through the process of installing and configuring SNMP on AlmaLinux 9 and integrating it with Nagios XI for centralized, real-time system visibility.

Prerequisites

Before proceeding, make sure you have:

  • AlmaLinux 9 with root or sudo privileges
  • A running Nagios XI server with the SNMP wizard enabled
  • Network connectivity between AlmaLinux and Nagios XI

Step 1: Install SNMP on AlmaLinux 9

  1. Install the SNMP daemon and utilities:
sudo dnf install net-snmp net-snmp-utils -y
  1. Verify SNMP installation:
snmpd -v

Step 2: Configure SNMP Access

SNMP v2c Configuration

  1. Backup the default config:
sudo cp /etc/snmp/snmpd.conf /etc/snmp/snmpd.conf.bak
  1. Edit the configuration file:
sudo nano /etc/snmp/snmpd.conf
  1. Add the following line (replace with your Nagios XI server IP):
rocommunity Str0ngC0mmunity 10.25.5.12
  1. Restart SNMP:
sudo systemctl restart snmpd.service

SNMP v3 Configuration (More Secure)

  1. Stop SNMP temporarily:
sudo systemctl stop snmpd.service
  1. Create a secure SNMP v3 user:
sudo net-snmp-create-v3-user -ro -a SHA -A Str0ng@uth3ntic@ti0n -x AES -X Str0ngPriv@cy nagios
  1. Restart SNMP:
sudo systemctl restart snmpd.service

Step 3: Configure Firewall Rules

If firewalld is active:

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

Confirm the rule:

sudo firewall-cmd --list-ports

Step 4: Enable SNMP on Boot

sudo systemctl enable snmpd.service

Step 5: Test SNMP Communication

Run from Nagios XI server:

For SNMP v2c:

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

Expected output:

iso.3.6.1.2.1.1.1.0 = STRING: "Linux almalinux 9 ..."

If no output appears, verify SNMP configuration and firewall.

Step 6: Add AlmaLinux Host to Nagios XI Using SNMP Wizard

1. Log into Nagios XI.

2. Go to Configure > Run a configuring wizard.

Screenshot 2025 03 12 083824 9
configuring wizard

3. Select Linux SNMP wizard.

Linux SNMP 7
Linux SNMP

4. Enter AlmaLinux 9 IP and SNMP settings (community string or SNMP v3 credentials).

Linux SNMP step 1 7
AlmaLinux 9 credentials

5. Choose metrics (CPU, memory, disk, processes).

6. Apply configuration and verify monitoring.

Common Issues & Fixes

SNMP Not Running

sudo journalctl -u snmpd --no-pager | tail -20
sudo systemctl restart snmpd.service

Host Appears “Down” in Nagios XI

sudo firewall-cmd --list-ports
sudo systemctl status snmpd

SNMP Credential Errors

  • Confirm SNMP version and credentials in both AlmaLinux and Nagios XI
  • Restart SNMP after any changes

Conclusion

You’ve successfully configured AlmaLinux 9 for SNMP monitoring in Nagios XI. This setup allows for secure, agentless tracking of system metrics in real-time. For advanced use, explore custom SNMP OIDs or additional Nagios XI plugins.

For support:

]]> Comprehensive Guide: Monitoring AlmaLinux 9 with NCPA in Nagios XI https://library.nagios.com/tutorials/comprehensive-guide-monitoring-almalinux-9-with-ncpa-in-nagios-xi/ Wed, 26 Mar 2025 18:46:52 +0000 https://library.nagios.com/?p=53465 The Nagios Cross-Platform Agent (NCPA) is a lightweight, flexible agent that enables centralized monitoring of AlmaLinux 9 from Nagios XI. Whether you’re monitoring CPU, memory, disk, or services, NCPA supports both active checks (pulled by Nagios) and passive checks (pushed via NRDP).

This guide outlines how to install, configure, and connect AlmaLinux 9 with Nagios XI using NCPA 3.x as of March 2025.

Prerequisites

  • A Nagios XI instance (latest version)
  • AlmaLinux 9 system (fully updated with sudo dnf update)
  • Root/sudo access
  • Port 5693 open between AlmaLinux and Nagios XI
  • firewalld installed and running

Step 1: Install NCPA on AlmaLinux 9

Option 1: Install via Nagios Repository (Recommended)

sudo rpm -Uvh https://repo.nagios.com/nagios/9/nagios-repo-9-1.el9.noarch.rpm
sudo dnf install ncpa -y

Option 2: Manual RPM Installation

cd /tmp
wget https://assets.nagios.com/downloads/ncpa/ncpa-latest-1.x86_64.rpm
sudo rpm -ivh ncpa-latest-1.x86_64.rpm

Ensure dependencies like python3 are installed if needed.

Step 2: Configure NCPA Token

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

Edit:

community_string = Str0ngT0k3n2025

Save and exit.

Step 3: Start and Enable NCPA

sudo systemctl restart ncpa
sudo systemctl enable ncpa
sudo systemctl status ncpa

Ensure status is active (running).

Step 4: Open Firewall Port 5693

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

Confirm 5693/tcp is listed.

Step 5: Verify NCPA Installation

Access the web interface:

https://<AlmaLinux-IP>:5693

Accept the certificate warning and log in using your token Str0ngT0k3n2025. The dashboard should show system stats.

Step 6: Add Host to Nagios XI

1. Log in to Nagios XI.

2. Go to Configure > Configuration Wizards > NCPA.

NCPA 6
NCPA

3. Enter:

  • IP: AlmaLinux IP
  • Port: 5693
  • Token: Str0ngT0k3n2025
rhel 2
NCPA Config step 1

4. Choose desired checks (CPU, memory, disk, processes).

5. Finish wizard and apply configuration.

Step 7: Optional – Setup Passive Checks (NRDP)

  1. In Nagios XI, go to Admin > Inbound Transfers > NRDP to get the URL and token.
  2. Edit ncpa.cfg:
[passive checks]
%HOSTNAME%|CPU Usage = cpu/percent --warning 60 --critical 80
  1. Restart NCPA:
sudo systemctl restart ncpa

Step 8: Troubleshooting Tips

  • Check service status:
sudo systemctl status ncpa
journalctl -u ncpa
  • Test connectivity:
nc -zv <AlmaLinux-IP> 5693
  • View logs:
cat /usr/local/ncpa/var/log/ncpa.log
  • Ensure token/IP match in Nagios XI wizard

Conclusion

With NCPA installed and configured on AlmaLinux 9, you’re now monitoring key system metrics in real time from Nagios XI. For advanced setups, explore encrypted transport or plugin-based checks via the NCPA API.

For help, visit:

]]> Effective Linux Server Monitoring with SNMP and Nagios XI on RHEL 9 https://library.nagios.com/documentation/snmp-and-nagios-xi-on-rhel-9/ Wed, 26 Mar 2025 17:07:56 +0000 https://library.nagios.com/?p=53462 Effective Linux server monitoring is critical for maintaining optimal performance and minimizing downtime. Simple Network Management Protocol (SNMP) provides an agentless approach to monitoring Linux servers, enabling seamless integration with Nagios XI to deliver real-time system insights and proactive issue detection.

This guide will walk you through the process of installing and configuring SNMP on RHEL 9, allowing you to integrate it easily with Nagios XI for efficient server monitoring.

Prerequisites

Before you begin, ensure the following:

  • A RHEL 9 system with root or sudo privileges.
  • Nagios XI installed and accessible, with the SNMP Wizard enabled.
  • A stable internet connection for downloading packages.

Step 1: Install SNMP on RHEL 9

To install SNMP and the required libraries, run the following command:

 sudo dnf install net-snmp net-snmp-utils -y

After installation, verify that SNMP has been successfully installed: 

snmpd -v

Step 2: Configure SNMP Access

SNMP v2c Configuration

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

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

2. Now, edit the SNMP configuration file:

sudo nano /etc/snmp/snmpd.conf

3. 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

4. Save the file and restart the SNMP service:

sudo systemctl restart snmpd.service

SNMP v3 Configuration (More Secure)

1. Stop the SNMP service temporarily:

sudo systemctl stop snmpd.service

2. 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
  • -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).

3. Restart the SNMP service:

sudo systemctl restart snmpd.service

Step 3: Configure Firewall Rules

1. If firewall is active (check with sudo systemctl status firewalld), allow SNMP traffic on UDP port 161:

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

2. Confirm firewall rules:

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

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

For SNMP v3:

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 4.18.0-305.19.1.el8.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 RHEL 8 Host to Nagios XI Using SNMP Wizard

Log in to Nagios XI.

Navigate to Configure > Run a Configuration Wizard.

Search for and select the Linux SNMP Wizard.

Screenshot 2025 03 14 074544 1
Linux SNMP

Enter the IP address of your RHEL 9 server and the SNMP credentials.

Click Next, then choose the system metrics you wish to monitor (CPU, memory, disk usage, network traffic, etc.).

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

Common Issues & Fixes

SNMP Service is Not Running

Check logs for errors:

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

Restart SNMP if necessary:

sudo systemctl restart snmpd.service

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 that the correct community string (for SNMP v2c) or authentication details (for SNMP v3) are used.

Restart the SNMP service after making changes: 

sudo systemctl restart snmpd.service

Conclusion

You’ve successfully configured SNMP on RHEL 9 for agentless monitoring with Nagios XI, providing real-time insights into system performance. For advanced setups, explore custom SNMP OIDs or additional Nagios XI plugins. For support, visit the Nagios Support Forum or the Nagios Knowledgebase.

]]> Forwarding RHEL 7 Logs to Nagios Log Server 2024R2 https://library.nagios.com/tutorials/forwarding-rhel-7-logs-to-nagios-log-server-2024r2/ Wed, 26 Mar 2025 16:45:01 +0000 https://library.nagios.com/?p=53428 Nagios Log Server delivers a robust solution for centralized log collection, analysis, and alerting, empowering administrators to monitor system health and stay ahead of potential issues. By forwarding logs to Nagios Log Server 2024R2, you gain real-time visibility into your infrastructure, enabling proactive monitoring and faster issue resolution. This guide will take you through the process of configuring your RHEL 7 system to seamlessly send logs to Nagios Log Server, ensuring efficient log management and enhanced system insights.

Prerequisites

  • Nagios Log Server 2024R2 is installed and accessible.
  • A RHEL 7 system with root or sudo access.
  • Network access between RHEL 7 and Nagios Log Server on port 5544.
  • rsyslog is installed (default on RHEL 7).

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

1. Open your browser and log into Nagios Log Server.

2. On the Home page, Click the + button in the left sidebar and the one at the bottom..

Screenshot 2025 08 22 155715
+ Add Log Source Button

3. Choose Linux as the source type.

    Screenshot 2025 08 25 153717
    + Linux

    Step 2: Configuring the RHEL 7 Log Source

    1. Download and Run the Setup Script

    If curl is not installed:

    sudo yum install -y curl

    Run the setup script:

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

    Replace <NagiosLogServerIP> with your actual server address.

    2. Verify the Script Execution

    Expected output:

    Detected rsyslog 8.1901.0
Detected rsyslog work directory /var/lib/rsyslog
Destination Log Server: 192.168.0.62:5544
Creating /etc/rsyslog.d/99-nagioslogserver.conf...
SELinux is disabled.
rsyslog configuration check passed.
Restarting rsyslog service with 'service'...
Redirecting to /bin/systemctl restart rsyslog.service
Okay.
rsyslog is running with the new configuration.
Visit your Nagios Log Server dashboard to verify that logs are being received.

    Step 3: Confirming Log Reception

    1. In Nagios Log Server:

    • Navigate to Dashboards > Search.
    • Search using:
    host.ip:<RHEL-IP>

    2. Send a Test Log Entry:

    logger "This is a test log entry"
    • Refresh the dashboard to see the entry.
    Screenshot 2025 08 25 154210
    test log entry

    Step 4: Accessing the Setup Script

    The setup script resides on the Nagios Log Server at:

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

    Step 5: Manual Setup (Optional)

    1.  Edit the rsyslog configuration:

    sudo nano /etc/rsyslog.d/.conf

    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
*.* @@192.168.1.123:5544
# ### end of the forwarding rule ###

    Replace /var/lib/rsyslog with the correct path if different, and 192.168.1.123 with the IP address of your Nagios Log Server.

    2. Restart rsyslog:

    sudo /etc/init.d/rsyslog restart

    Step 6: Adding More Log Sources

    Use the + Add Log Source button to configure:

    • Windows event logs
    • Application logs
    • File Monitoring
    • Archived logs
    Screenshot 2025 08 22 155127
    Add Log Source

    Troubleshooting Tips

    1. Check rsyslog Status:

    systemctl status rsyslog

    Start it if needed:

    sudo systemctl start rsyslog

    2. Verify Network Access:

    Ensure RHEL 7 can reach the Nagios Log Server on port 5544.

    3. Check Firewall:

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

    4. Review Logs:

    sudo grep rsyslog /var/log/messages

    On the Log Server:

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

    Video Tutorial

    For a step-by-step walkthrough, watch this video:

    Conclusion

    You’ve successfully configured RHEL 7 to forward logs to Nagios Log Server 2024R2. This integration supports centralized monitoring, faster troubleshooting, and improved visibility.

    For further help, check the Nagios Knowledgebase or Nagios Support Forums.

    ]]>         Monitoring RHEL 7 with NCPA in Nagios XI: A Complete Guide https://library.nagios.com/tutorials/monitoring-rhel-7-with-ncpa-in-nagios-xi-a-complete-guide/ Wed, 26 Mar 2025 12:55:18 +0000 https://library.nagios.com/?p=53124 Ensuring the health and stability of your RHEL 7 servers is vital for seamless IT operations. The Nagios Cross-Platform Agent (NCPA) offers a modern, agent-based approach to monitoring, providing real-time insights into critical system metrics such as CPU usage, memory utilization, disk space, and network activity. Unlike traditional SNMP-based monitoring, NCPA leverages a secure RESTful API for enhanced data collection and integration with Nagios XI.

    This step-by-step guide will walk you through installing and configuring NCPA on RHEL 7, ensuring seamless monitoring and proactive issue resolution with Nagios XI.

    Prerequisites

    Before proceeding, ensure you have:

    • A RHEL 7 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 RHEL 7 is using the Nagios repository. To add the repository, run:

    sudo rpm -Uvh https://repo.nagios.com/nagios/7/nagios-repo-7-2.el7.noarch.rpm
sudo yum update -y

    After adding the repository, update your package list to ensure you have access to the latest packages.

    Step 2: Install NCPA on RHEL 7

    Once the repository is configured, install the NCPA agent using:

    sudo yum install ncpa -y

    Verify the installation by checking the package version:

    rpm -q ncpa

    Expected output: ncpa-<version>.el7.x86_64 (e.g., ncpa-3.1.1-1.el7.x86_64).

    Step 3: Configure NCPA

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

    1. Open the configuration file:

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

    2. Locate the line:

     community_string = mytoken

    3. Replace mytoken with a strong, unique token (e.g., K9pL3mX7vR2tQ8nJ) to enhance security.

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

    Step 4: Enable and Start the NCPA Service

    Ensure NCPA runs automatically at boot and starts immediately by executing:

    sudo systemctl enable ncpa
sudo systemctl start ncpa

    Check the service status to confirm it is active:

    sudo systemctl status ncpa

    You should see Active: active (running) in the output.

    Step 5: Configure Firewall Rules

    If firewall is active (check with sudo systemctl status firewalld), allow NCPA traffic on port 5693:

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

    Confirm the firewall rules with:

    sudo firewall-cmd --list-ports

    Step 6: Test NCPA Installation

    After configuring the firewall, confirm that NCPA is accessible:

    1. Open a web browser and navigate to:

    https://<NCPA_IP_Address>:5693/

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

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

    Step 7: Add RHEL 7 Host to Nagios XI Using the NCPA Wizard

    1. Log in to Nagios XI.

    2. Navigate to Configure > Run a Configuration Wizard.

    3. Search for and select NCPA.

    NCPA 5
    NCPA

    4. Enter the RHEL 7 server’s IP address and the API token you set in the NCPA configuration.

    rhel 1
    RHEL 7 Credentials

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

    6. Apply the configuration and verify that Nagios XI is collecting data from your RHEL 7 host.

    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 for proper IP and token settings.

    Incorrect API Token Error

    • Confirm the correct API token is set in /usr/local/ncpa/etc/ncpa.cfg.
    • Restart the NCPA service after making changes.

    Conclusion

    You have successfully installed and configured NCPA on RHEL 7 for monitoring with Nagios XI. This setup enables efficient tracking of system performance metrics and ensures proactive issue resolution through real-time monitoring. For further assistance, refer to the Nagios Support Forum or the Nagios Knowledgebase.

    ]]>         Comprehensive Guide to Monitoring RHEL 7 with SNMP in Nagios XI https://library.nagios.com/tutorials/comprehensive-guide-to-monitoring-rhel-7-with-snmp-in-nagios-xi/ Tue, 25 Mar 2025 14:37:10 +0000 https://library.nagios.com/?p=53135 Maintaining the health and performance of your RHEL 7 servers is essential for a stable IT environment. SNMP (Simple Network Management Protocol) offers a streamlined, agentless approach to monitoring, making it an efficient choice for integrating with Nagios XI.

    In this guide, you’ll learn how to set up and configure SNMP on RHEL 7, allowing Nagios XI to track key system metrics effortlessly using its built-in SNMP monitoring capabilities.

    Prerequisites

    Ensure you have the following before starting:

    • A RHEL 7 system with root or sudo privileges
    • Nagios XI is installed and accessible
    • SNMP Wizard enabled in Nagios XI
    • Network access between the RHEL 7 server and Nagios XI

    Step 1: Install SNMP on RHEL 7

    1. To install SNMP and the required libraries, run:

    sudo dnf install net-snmp net-snmp-utils -y

    2. After installation, verify the installed version:

    snmpd -v

    Step 2: Configure SNMP Access

    SNMP v2c Configuration

    Backup config:

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

    Create a new config:

    echo 'rocommunity Str0ngC0mmunity 10.25.5.12' > /etc/snmp/snmpd.conf

    Replace Str0ngC0mmunity and 10.25.5.12 accordingly.

    Restart SNMP:

    systemctl restart snmpd.service

    SNMP v3 Configuration

    Stop service:

    systemctl stop snmpd.service

    Create user:

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

    Start service:

    sudo systemctl restart snmpd.service

    Step 3: Configure Firewall Rules

    Allow SNMP traffic:

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

    Verify:

    firewall-cmd --list-ports

    Step 4: Enable SNMP on Boot

    sudo systemctl enable snmpd.service

    Step 5: Test SNMP Communication

    From the Nagios XI server:

    SNMP v2c:

    snmpwalk -v2c -c Str0ngC0mmunity 10.25.5.12

    SNMP v3:

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

    Expected output:

    iso.3.6.1.2.1.1.1.0 = STRING: "Linux rhel7 3.10.0-1160.el7.x86_64"

    If no data is returned, check the firewall and SNMP config.

    Step 6: Add RHEL 7 Host to Nagios XI

    1. Log in to Nagios XI.

    2. Navigate to Configure > Run a configuring wizard.

    3. Select the Linux SNMP wizard.

    Linux SNMP 5
    Linux SNMP

    4. Enter the RHEL 7 server’s IP address and SNMP credentials.

    Linux SNMP step 1 5
    REHL 7 Credentials

    5. Select metrics to monitor (CPU, memory, disk, network traffic, etc.).

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

    Common Issues & Fixes

    SNMP Service is Not Running

    1. Check logs for errors:

    journalctl -u snmpd --no-pager | tail -20

    2. Restart SNMP if necessary:

    systemctl restart snmpd.service

    Host Appears “Down” in Nagios XI

    1. Confirm SNMP is running:

    systemctl status snmpd

    2. Check if port 161 is open:

    firewall-cmd --list-ports

    3. Verify SNMP credentials in Nagios XI.

    Conclusion

    You’ve now configured SNMP on RHEL 7 for agentless monitoring in Nagios XI. This setup improves visibility into your server’s health and performance.

    For additional resources:

    ]]>